Equine influenza is a highly contagious respiratory disease caused by influenza A viruses, specifically affecting horses. The disease is characterized by symptoms such as fever, coughing, nasal discharge, and lethargy. Transmission occurs primarily through aerosolized droplets and direct contact, leading to rapid spread among susceptible populations. Vaccination is a common preventive measure, though the virus's ability to mutate necessitates ongoing surveillance and vaccine updates. This page gathers peer-reviewed research studies and scholarly articles that explore the virology, epidemiology, clinical presentation, and management strategies of equine influenza, with a focus on its impact on equine health and welfare.
Larson KR, Heil GL, Chambers TM, Capuano A, White SK, Gray GC.Equine influenza virus (EIV) is considered enzootic in North America and experimental studies have documented human EIV infections. Methods: This cross-sectional study examined 94 horse-exposed and 34 non-exposed controls for serological evidence of EIV infection. Sera were evaluated for antibodies against three EIV and two human H3N2 viruses using microneutralization (MN), neuraminidase inhibition (NI), enzyme-linked lectin (ELLA), and hemagglutination inhibition (HI) serological assays. Risk factor analyses were conducted using logistic regression and proportional odds modeling. Results: The...
Woodward A, Rash AS, Medcalf E, Bryant NA, Elton DM.Equine influenza is a major cause of respiratory infections in horses and causes widespread epidemics, despite the availability of commercial vaccines. Antigenic drift within the haemagglutinin (HA) glycoprotein is thought to play a part in vaccination breakdown. Here, we carried out a detailed investigation of the 1989 UK outbreak, using reverse genetics and site-directed mutagenesis, to determine the individual contribution of amino acid substitutions within HA. Mutations at positions 159, 189 and 227 all altered antigenicity, as measured by haemagglutination-inhibition assays. We also compa...
Legrand LJ, Pitel PH, Cullinane AA, Fortier GD, Pronost SL.REASON FOR PERFORMING THIS STUDY: Equine influenza virus (EIV) is considered the most economically important equine respiratory pathogen worldwide. The H3N8 subtype, responsible for all outbreaks of equine influenza globally, evolves perpetually. Mutations in the genome of these viruses have the potential to modify their antigenic properties and recognition by pre-existing antibodies. Objective: The aim of this study was to determine the genetic evolution of EIV strains in France and to compare it with the evolution of strains isolated globally. Analysis of the sequence data was performed to i...
Gilkerson JR, Bailey KE, Diaz-Méndez A, Hartley CA.Many viral agents have been associated with respiratory disease of the horse. The most important viral causes of respiratory disease in horses are equine influenza and the equine alphaherpesviruses. Agents such as equine viral arteritis virus, African horse sickness virus, and Hendra virus establish systemic infections. Clinical signs of disease resulting from infection with these agents can manifest as respiratory disease, but the respiratory tract is not the major body system affected by these viruses. Treatment of viral respiratory disease is generally limited to supportive therapies, where...
Pusterla N, Kass PH, Mapes S, Wademan C, Akana N, Barnett C, MacKenzie C, Vaala W.Recent surveillance studies for equine respiratory viruses have shown that equine influenza virus (EIV) continues to be a prevalent respiratory virus of equids throughout the United States and Europe. Objective: To gain a better understanding of the prevalence and epidemiology of EIV shed by horses, mules and donkeys in the United States from March 2010 to November 2013. Methods: 2,605 equids. Methods: Nasal secretions from index cases with acute onset of respiratory disease were tested by qPCR for EIV. Multilevel logistic regression was used to model the association between EIV status and pre...
Davis EG, Bello NM, Bryan AJ, Hankins K, Wilkerson M.Protection from infectious disease requires antigen-specific immunity. In foals, most vaccine protocols are delayed until 6 months to avoid maternal antibody interference. Susceptibility to disease may exist prior to administration of vaccination at age 4-6 months. Objective: The aim of this investigation was to characterise immune activation among healthy foals in response to a multivalent vaccine protocol and compare immune responses when foals were vaccinated at age either 90 or 180 days. Methods: Randomised block design. Methods: Twelve healthy foals with colostral transfer were blocked fo...
Equine influenza in England and Scotland, Significant numbers of outbreaks of equine herpesvirus 1 neurological disease in the USA, Summary of surveillance testing, April to June 2014. These are among matters discussed in the most recent quarterly equine disease surveillance report, prepared by Defra, the Animal Health Trust and the British Equine Veterinary Association.
Ryan M, Gildea S, Walsh C, Cullinane A.More knowledge of equine influenza (EI) vaccine usage in training yards and the factors that influence serological response to vaccination are required to determine evidence-based vaccination strategies. Objective: The aim of this study was to ascertain the vaccination history of a population of Thoroughbred racehorses and identify factors that impacted on their antibody titres against EI. Methods: Observational field study. Methods: The study population consisted of 102 vaccinated Thoroughbred horses in training on a single premises. The vaccination histories recorded in their official passpo...
Jiménez D, Romero-Zuñiga JJ, Dolz G.Blood samples from 181 equines from the Central Valley of Costa Rica were collected in the year 2012 to determine the presence of antibodies against selected infectious agents in horses and to determine the risk factors associated with these agents. The presence of antibodies against Equine Infectious Anemia Virus (EIAV), Equine Herpes Virus 1 and 4 (EHV-1 and EHV-4), West Nile Virus (WNV), Influenza A Virus (IAV), Equine Viral Arteritis Virus (EVAV), Babesia caballi, Theileria equi, Neospora caninum and Chlamydia abortus was determined using commercial assays, and risk factors associated with...
Paillot R.Equine influenza (EI) is a major respiratory disease of horses, which is still causing substantial outbreaks worldwide despite several decades of surveillance and prevention. Alongside quarantine procedures, vaccination is widely used to prevent or limit spread of the disease. The panel of EI vaccines commercially available is probably one of the most varied, including whole inactivated virus vaccines, Immuno-Stimulating Complex adjuvanted vaccines (ISCOM and ISCOM-Matrix), a live attenuated equine influenza virus (EIV) vaccine and a recombinant poxvirus-vectored vaccine. Several other strateg...
Alymova IV, York IA, McCullers JA.PB1-F2 protein, expressed from an alternative reading frame of most influenza A virus (IAV) PB1 segments, may possess specific residues associated with enhanced inflammation (L62, R75, R79, and L82) and cytotoxicity (I68, L69, and V70). These residues were shown to increase the pathogenicity of primary viral and secondary bacterial infections in a mouse model. In contrast to human seasonal influenza strains, virulence-associated residues are present in PB1-F2 proteins from pandemic H1N1 1918, H2N2 1957, and H3N2 1968, and highly pathogenic H5N1 strains, suggesting their contribution to viruses...
Gaíva e Silva L, Borges AM, Villalobos EM, Lara Mdo C, Cunha EM, de Oliveira AC, Braga IA, Aguiar DM.The prevalence of antibodies against Equine Influenza Virus (EIV) was determined in 529 equines living on ranches in the municipality of Poconé, Pantanal area of Brazil, by means of the hemagglutination inhibition test, using subtype H3N8 as antigen. The distribution and possible association among positive animal and ranches were evaluated by the chi-square test, spatial autoregressive and multiple linear regression models. The prevalence of antibodies against EIV was estimated at 45.2% (95% CI 30.2 - 61.1%) with titers ranging from 20 to 1,280 HAU. Seropositive equines were found on 92.0% of...
Tabynov K, Kydyrbayev Z, Ryskeldinova S, Assanzhanova N, Kozhamkulov Y, Inkarbekov D, Sansyzbay A.To design and evaluate the safety and immunogenicity of a modified-live vaccine to prevent equine influenza virus (EIV) infection based on the novel reassortant cold-adapted strain A/HK/Otar/6:2/2010. Methods: Surface proteins (HA, NA) from the wild-type strain A/equine/Otar/764/2007 (H3N8) and internal proteins (PB2, PB1, PA, NP, M, NS) from the attenuated cold-adapted donor strain A/Hong Kong/1/68/162/35CA (H3N2) were included in the vaccine. Horses were administered 10(9.2) EID50 /mL of the modified-live vaccine or saline solution using a nasal spray. The clinical condition of the animals w...
Na W, Song M, Yeom M, Park N, Kang B, Moon H, Jeong DG, Kim JK, Song D.H3N8 equine influenza virus (EIV) causes respiratory diseases in the horse population, and it has been demonstrated that EIV can transmit into dogs owing to its availability on receptors of canine respiratory epithelial cells. Recently, we isolated H3N8 EIV from an EIV-vaccinated horse that showed symptoms of respiratory disease, and which has a partially truncated nonstructural gene (NS). However, it is not clear that the NS-truncated EIV has an ability to cross the host species barrier from horses to dogs as well. Here, we experimentally infected the NS-truncated H3N8 EIV into dogs, and moni...
Rosanowski SM, Cogger N, Rogers CW, Stevenson MA.New Zealand has never experienced an equine influenza (EI) outbreak. The 2007 outbreak of EI in Australia showed that in a naïve population EI spreads rapidly and substantial efforts (in terms of movement restrictions, mass vaccination and post-vaccination surveillance) were required to achieve eradication. To control EI, it is essential that animal health authorities have well-defined strategies for containment, control and eradication in place before an incursion occurs. A spatially explicit stochastic simulation model, InterSpread Plus, was used to evaluate EI control strategies for the Ne...
Landolt GA.For decades the horse has been viewed as an isolated or "dead-end" host for influenza A viruses, with equine influenza virus being considered as relatively stable genetically. Although equine influenza viruses are genetically more stable than those of human lineage, they are by no means in evolutionary stasis. Moreover, recent transmission of equine-lineage influenza viruses to dogs also challenges the horse's status as a dead-end host. This article reviews recent developments in the epidemiology and evolution of equine influenza virus. In addition, the clinical presentation of equine influenz...
Rash A, Woodward A, Bryant N, McCauley J, Elton D.H3N8 equine influenza virus (EIV) has caused disease outbreaks in horses across the world since its first isolation in 1963. However, unlike human, swine and avian influenza, there is relatively little sequence data available for this virus. The majority of published sequences are for the segment encoding haemagglutinin (HA), one of the two surface glycoproteins, making it difficult to study the evolution of the other gene segments and determine the level of reassortment occurring between sub-lineages. Methods: To facilitate the generation of full genome sequences for EIV, we developed a simpl...
Manuja BK, Manuja A, Dahiya R, Singh S, Sharma RC, Gahlot SK.Equine influenza (EI) is primarily an infection of the upper respiratory tract and is one of the major infectious respiratory diseases of economic importance in equines. Re-emergence of the disease, species jumping by H3N8 virus in canines and possible threat of human pandemic due to the unpredictable nature of the virus have necessitated research on devising strategies for preventing the disease. The myxovirus resistance protein (Mx) has been reported to confer resistance to Orthomyxo virus infection by modifying cellular functions needed along the viral replication pathway. Polymorphisms and...
Collins PJ, Vachieri SG, Haire LF, Ogrodowicz RW, Martin SR, Walker PA, Xiong X, Gamblin SJ, Skehel JJ.In 2004 an hemagglutinin 3 neuraminidase 8 (H3N8) equine influenza virus was transmitted from horses to dogs in Florida and subsequently spread throughout the United States and to Europe. To understand the molecular basis of changes in the antigenicity of H3 hemagglutinins (HAs) that have occurred during virus evolution in horses, and to investigate the role of HA in the equine to canine cross-species transfer, we used X-ray crystallography to determine the structures of the HAs from two antigenically distinct equine viruses and from a canine virus. Structurally all three are very similar with...
BMC research notesJuly 12, 2014
Volume 7 448 doi: 10.1186/1756-0500-7-448
Boukharta M, Zakham F, Touil N, Elharrak M, Ennaji MM.The equine influenza (EI) is an infectious and contagious disease of the upper respiratory tract of horses. Two outbreaks were notified in Morocco during 1997 and 2004 respectively in Nador and Essaouira. The aims of the present study concern the amino acids sequences comparison with reference strain A/equine/Miami/1963(H3N8) of the HA2 subunit including the cleavage site of three equine influenza viruses (H3N8) isolated in Morocco: A/equine/Nador/1/1997(H3N8), A/equine/Essaouira/2/2004 (H3N8) and A/equine/Essaouira/3/2004 (H3N8). Results: The obtained results demonstrated that the substitutio...
Balasuriya UB, Lee PY, Tiwari A, Skillman A, Nam B, Chambers TM, Tsai YL, Ma LJ, Yang PC, Chang HF, Wang HT.Equine influenza (EI) is an acute, highly contagious viral respiratory disease of equids. Currently, equine influenza virus (EIV) subtype H3N8 continues to be the most important respiratory pathogen of horses in many countries around the world. The need to achieve a rapid diagnosis and to implement effective quarantine and movement restrictions is critical in controlling the spread of EIV. In this study, a novel, inexpensive and user-friendly assay based on an insulated isothermal RT-PCR (iiRT-PCR) method on the POCKIT™, a field-deployable device, was described and validated for point-of-nee...
Balasuriya UB.The primary goals of this chapter are to discuss common viral RNA isolation and purification methods that are routinely used by various diagnostic laboratories, to highlight the advantages and drawbacks of each method, and to identify the most suitable and reliable method to increase the sensitivity and specificity of RT-PCR assays for the detection of equine influenza virus (EIV) in clinical specimens. Our experiences and review of literature show that magnetic bead-based nucleic extraction methods (manual and automatic) work well for isolation and purification of EIV RNA from nasal swab spec...
Chambers TM, Reedy SE.Equine influenza viruses are cultured in embryonated hen eggs, or in mammalian cells, generally Madin-Darby canine kidney (MDCK) cells, using methods much the same as for other influenza A viruses. Mutations associated with host adaptation occur in both eggs and MDCK cells, but the latter show greater heterogeneity and eggs are the generally preferred host. Both equine-1 H7N7 and equine-2 H3N8 viruses replicate efficiently in 11-day-old eggs, but we find that equine-1 viruses kill the embryos whereas equine-2 viruses do not.
Balasuriya UB.Equine influenza (EI) is a highly contagious disease of horses caused by the equine influenza virus (EIV) H3N8 subtype. EI is the most important respiratory virus infection of horses and can disrupt major equestrian events and cause significant economic losses to the equine industry worldwide. Influenza H3N8 virus spreads rapidly in susceptible horses and can result in very high morbidity within 24-48 h after exposure to the virus. Therefore, rapid and accurate diagnosis of EI is critical for implementation of prevention and control measures to avoid the spread of EIV and to reduce the economi...
Chambers TM, Reedy SE.In horses, presumptive diagnosis of equine influenza is commonly made on the basis of clinical signs. This alone is insufficient for confirmation of equine influenza, because other equine infectious respiratory diseases can in some degree have similar clinical presentations. Surveillance and control of equine influenza also necessitate detection of subclinical cases. Effective diagnosis of equine influenza virus infection is critically dependent on obtaining adequate specimens of virus-containing respiratory secretions for testing. These specimens are also valuable as sources for isolation of ...
Chambers TM.Equine influenza virus (EIV) is a common respiratory pathogen of horses and other equids in most parts of the world. EIV are Type A influenza viruses and two subtypes are known: H3N8 and H7N7. Both are believed to have evolved from avian influenza virus ancestors. The H3N8 subtype circulates widely, but the H7N7 subtype is thought to be extinct. The clinical disease in horses, caused by either subtype, is an upper respiratory infection of varying severity depending upon the immune status of the individual animal. It is not normally life-threatening in itself except in very young foals; however...
Chambers TM, Reedy SE.Serologic tests for equine influenza virus (EIV) antibodies are used for many purposes, including retrospective diagnosis, subtyping of virus isolates, antigenic comparison of different virus strains, and measurement of immune responses to EIV vaccines. The hemagglutination-inhibition (HI), single radial hemolysis (SRH), and serum micro-neutralization tests are the most widely used for these purposes and are described here. The presence of inhibitors of hemagglutination in equine serum complicates interpretation of HI assay results, and there are alternative protocols (receptor-destroying enzy...
Newton JR, Verheyen K, Wood JL, Yates PJ, Mumford JA.In 1998, equine influenza was diagnosed by serology and nucleoprotein enzyme-linked immunosorbent assay as the cause of acute respiratory disease in vaccinated and unvaccinated horses in the UK. The signs were generally milder in vaccinated horses and completely susceptible animals showed the most severe signs, including pyrexia, inappetence, coughing, mucopurulent nasal discharge and secondary bacterial pneumonia. In a detailed investigation of an outbreak among 52 vaccinated thoroughbreds in a flat racing yard, more than 60 per cent of the horses seroconverted on the evidence of paired serum...
Nemoto M, Yamanaka T, Bannai H, Tsujimura K, Kondo T, Matsumura T.Reverse transcription loop-mediated isothermal amplification (RT-LAMP) was applied to the detection of equine influenza virus (EIV). Because equine influenza is caused currently by EIV of the H3H8 subtype, the RT-LAMP primer set was designed to target the hemagglutinin gene of this subtype. The detection limit of the RT-LAMP assay was a virus dilution of 10(-5); which was 10(3) times more sensitive than the Espline Influenza A&B-N test and 10 times more sensitive than a reverse transcription polymerase chain reaction (RT-PCR) assay. The specificity of the RT-LAMP assay was examined by usin...
Burnell FJ, Holmes MA, Roiko AH, Lowe JB, Heil GL, White SK, Gray GC.Equine influenza virus (EIV) is considered enzootic in Europe (except Iceland), Asia, North Africa, and North and South America. When EIV outbreaks occur they may severely impact the equine and tourist industries. Australia faced its first EIV outbreak beginning in August of 2007. The outbreak was concentrated in New South Wales and Queensland, with more than 1400 confirmed EIV infections in horses during the first month. Rapid response from the equine industry and the federal government was successful and Australia was declared free from EIV by the end of 2007. Objective: This cross-sectional...
Firestone SM, Schemann KA, Toribio JA, Ward MP, Dhand NK.The 2007 epidemic of equine influenza in Australia provided an opportunity to investigate the effectiveness of on-farm biosecurity measures in preventing the spread of a novel pathogen in a largely naive population. We conducted a case-control study of 200 horse premises from highly affected regions of the state of New South Wales (NSW), to investigate risk factors for the spread of equine influenza onto horse premises, specifically, non-compliance with biosecurity measures recommended to horse owners by the relevant animal health authority, the NSW Department of Primary Industries. The study ...
Paillot R, Prowse L, Donald C, Medcalf E, Montesso F, Bryant N, Watson J, Jeggo M, Elton D, Newton R, Trail P, Barnes H.An outbreak of H3N8 Equine Influenza virus (EIV) that occurred in vaccinated horses in Japan was caused by a genetically divergent EIV isolate of the Florida clade 1 sub-lineage. This virus subsequently entered Australia where it infected thousands of immunologically naïve horses. The objective of this study was to evaluate the ability of a non-updated whole inactivated equine influenza (EI) vaccine to protect if used in the face of an outbreak induced by a virus similar to the ones circulating in Japan and Australia in 2007. Seven naïve Welsh mountain ponies were immunised twice with the co...
Khurelbaatar N, Krueger WS, Heil GL, Darmaa B, Ulziimaa D, Tserennorov D, Baterdene A, Anderson BD, Gray GC.In recent years, Mongolia has experienced recurrent epizootics of equine influenza virus (EIV) among its 2·1 million horses and multiple incursions of highly pathogenic avian influenza (HPAI) virus via migrating birds. No human EIV or HPAI infections have been reported. In 2009, 439 adults in Mongolia were enrolled in a population-based study of zoonotic influenza transmission. Enrollment sera were examined for serological evidence of infection with nine avian, three human, and one equine influenza virus strains. Seroreactivity was sparse among participants suggesting little human risk of zoo...
Na W, Yeom M, Yuk H, Moon H, Kang B, Song D.This study provides information regarding vaccine research and the epidemiology of influenza virus in neglected hosts (horses and dogs). Equine influenza virus (EIV) causes a highly contagious disease in horses and other equids, and outbreaks have occurred worldwide. EIV has resulted in costly damage to the horse industry and has the ability of cross the host species barrier from horses to dogs. Canine influenza is a virus of equine or avian origin and infects companion animals that live in close contact with humans; this results in possible exposure to the seasonal epizootic influenza virus. ...
Spence KL, O'Sullivan TL, Poljak Z, Greer AL.Identifying the contact structure within a population of horses attending a competition is an important element towards understanding the potential for the spread of equine pathogens as the horses subsequently travel from location to location. However, there is limited information in Ontario, Canada to quantify contact patterns of horses. The objective of this study was to describe the network of potential contacts associated with an equestrian show to determine how this network structure may influence potential disease transmission. Results: This was a descriptive study of horses attending an...
Mumford EL, Traub-Dargatz JL, Salman MD, Collins JK, Getzy DM, Carman J.To develop a system to monitor and detect acute infections of the upper respiratory tract (i.e., nares, nasopharynx, and pharynx) in horses and to assess the association among specific viral infections, risk factors, and clinical signs of disease. Methods: Prospective study. Methods: 151 horses with clinical signs of acute infectious upper respiratory tract disease (IURD) from 56 premises in Colorado. Methods: Health management data, blood samples, and nasal or nasopharyngeal swab samples were obtained for 151 horses with clinical signs of acute IURD. Of these horses, 112 had an additional blo...
Paillot R, Marcillaud Pitel C, D'Ablon X, Pronost S.To date, vaccination is one of the most efficient methods of prevention against equine infectious diseases. The vaccinology session, which was organised during the annual meeting of the French Equine Veterinarians Association (AVEF) at Reims (France) in 2016, aimed to approach three subjects of importance for the equine industry. Vaccination against three major equine diseases were used as examples: equine influenza (equine influenza virus), rhinopneumonitis (equine herpes virus 1/4), and tetanus ( neuro-toxin). (1) Emergency vaccination: while it has been very successful to reduce the impact ...
Morley PS, Townsend HG, Bogdan JR, Haines DM.To identify risk factors associated with respiratory tract disease in horses during 3 epidemics caused by influenza virus infections. Methods: Cross-sectional and prospective longitudinal observational studies. Methods: 1,163 horses stabled at a Thoroughbred racetrack. Methods: Investigations were conducted during a 3-year period. An epidemic of respiratory tract disease caused by influenza virus infections was identified in each year. Routine observations and physical examinations were used to classify horses' disease status. Data were analyzed to identify factors associated with development ...
Yamanaka T, Nemoto M, Bannai H, Tsujimura K, Kondo T, Matsumura T, Muranaka M, Ueno T, Kinoshita Y, Niwa H, Hidari KI, Suzuki T.Since equine influenza A virus (H3N8) was transmitted to dogs in the United States in 2004, the causative virus, which is called canine influenza A virus (CIV), has become widespread in dogs. To date, it has remained unclear whether or not CIV-infected dogs could transmit CIV to horses. To address this, we tested whether or not close contact between horses and dogs experimentally infected with CIV would result in its interspecies transmission. Methods: Three pairs of animals consisting of a dog inoculated with CIV (10(8.3) egg infectious dose 50/dog) and a healthy horse were kept together in i...
Birch-Machin I, Rowan A, Pick J, Mumford J, Binns M.The nucleotide sequence of the nonstructural protein NS1 of the influenza virus A/equine 2/Suffolk/89 was determined and found to be 97% identical to that of A/equine 2/Miami/63. A similar level of identity was shown for the deduced NS1 amino acid sequence. The NS1 gene was expressed, in its entirety and in part, as fusion proteins with glutathione S-transferase using the pGEX-3X expression vector. Antibodies to NS1 protein were detected in serum samples from ponies experimentally infected with influenza virus, but not in animals vaccinated with whole inactivated virus or in unprimed control a...
Glass K, Wood JL, Mumford JA, Jesset D, Grenfell BT.This paper demonstrates that a simple stochastic model can capture the features of an epidemic of equine influenza in unvaccinated horses. When the model is modified to consider vaccinated horses, we find that vaccination dramatically reduces the incidence and size of epidemics. Although occasional larger outbreaks can still occur, these are exceptional. We then look at the effects of vaccination on a yard of horses, and in particular at the relationship between pre-challenge antibody level and quantity of virus shed when challenged with the virus. While on average, a high antibody level impli...
Yamanaka T, Cullinane A, Gildea S, Bannai H, Nemoto M, Tsujimura K, Kondo T, Matsumura T.The protection induced by an equine influenza (EI) vaccine strain depends on its antigenic relatedness to the challenge virus. Although the World Organisation for Animal Health (OIE) recommend that both Florida sublineage clade 1 (Fc1) and clade 2 (Fc2) viruses should be included in EI vaccines, Japanese EI vaccines have not, thus far, been updated to include a Fc2 virus. Objective: To evaluate the efficacy of antibodies raised against Japanese EI vaccine strains in the neutralisation of recent Fc2 viruses. Methods: Antigenic analysis. Methods: Virus neutralisation tests were performed using a...
Lopez AM, Hecker R, Mutwiri G, van Drunen Littel-van den Hurk S, Babiuk LA, Townsend HG.Previous studies have shown that protection against equine influenza virus (EIV) is partially mediated by virus-specific IgGa and IgGb. In this study we tested whether addition of a CpG ODN formulation to a commercial killed virus vaccine would enhance EIV-specific IgGa and IgGb antibody responses, and improve protection against an experimental EIV challenge. Thirty naïve horses were assigned to one of three groups and vaccinated as follows: 10 were given vaccine (Encevac TC4, Intervet Inc.) alone, 10 were given vaccine plus 0.25 mg CpG ODN 2007 formulated with 30% Emulsigen (CpG/Em), and 10 ...
Mumford EL, Traub-Dargatz JL, Carman J, Callan RJ, Collins JK, Goltz KL, Romm SR, Tarr SF, Salman MD.Horses vaccinated against common agents of infectious upper respiratory disease (IURD) may not have detectable serum antibody and may not be protected from clinical disease. Objective: The objectives of this study were to 1) investigate the serological response of horses to vaccination against influenza virus (H3N8 and H7N7) and equine herpesviruses (EHV) in a field setting and 2) evaluate associations among vaccination status, serum antibody concentrations, and occurrences of IURD in monitored horses. Methods: In this study, horses on 6 Colorado premises were vaccinated parenterally against i...
Daly JM, Sindle T, Tearle J, Barquero N, Newton JR, Corning S.Surveillance of equine influenza viruses has suggested that strains included in currently licensed vaccines are a poor match for those predominantly circulating in the field. Objective: To assess the ability of Duvaxyn IE-T Plus to provide cross protection against the newly evolved South Africa/4/03 (H3N8) strain of equine influenza virus. Methods: The vaccine efficacy was evaluated by challenge infection with influenza strain A/eq/South Africa/4/03 (H3N8) 2 weeks after a primary course of 2 vaccinations with Duvaxyn IE-T Plus given at a 4-week interval. The outcome of challenge in vaccinated ...
Gildea S, Sanchez Higgins MJ, Johnson G, Walsh C, Cullinane A.There is a lack of information concerning concurrent administration of vaccines against equine influenza virus (EIV) and equine herpesvirus 1 and 4 (EHV-1/4). The primary objective of this study was to determine the impact of the concurrent use of EIV and EHV-1/4 vaccines in Thoroughbred racehorses on their humoral immune response to EIV. This study was carried out on a population of 30 horses using an inactivated whole-virus EIV vaccine and an inactivated EHV-1/4 vaccine. Horses were randomly allocated to vaccination group A or B. Horses in group A were vaccinated against EIV and EHV-1/4 2 we...
Damiani AM, Scicluna MT, Ciabatti I, Cardeti G, Sala M, Vulcano G, Cordioli P, Martella V, Amaddeo D, Autorino GL.During local respiratory disease outbreaks, occurring in 2003 and 2004 in horse training stables within race-tracks in Rome, and on a stud horse farm in Bari in 2005, four strains of equine influenza (EI) virus were isolated. All outbreaks occurred in flu-vaccinated horses. Here, we are reporting the results of the genetic characterization of these isolates, together with that of another EI virus strain isolated in 1999 from a dead foal presenting pulmonary lesions. Alignment and phylogenetic analyses were carried out using the haemagglutinin amino acid sequences. The Rome and Bari isolates we...
Webster WR.In August 2007 equine influenza (EI) was diagnosed in Australia's horse population following the failure to contain infection in quarantine after the importation of one or more infected horses. The response had many unique features, and addressed financial, social, economic, human and animal health, trade and recovery issues. The outbreak and the associated control measures had a vast impact on individual horse owners, the horse industry and associated sectors in both infected and uninfected states.
Burrows R, Denyer M, Goodridge D, Hamilton F.Experimental ponies developed signs of disease four days after the intranasal instillation of A/England 1/79 equine influenza virus and virus was recovered from the nasopharynx from the second to the ninth day. No significant antigenic difference was found between the virus and the prototype A/Miami 1/63 virus, using post infection ferret and chicken sera and post vaccination pony sera. No antigenic differences were found between four viruses isolated between January and July 1979, although some differences were found in their ability to detect haemagglutination inhibiting antibody in convales...
Yamagishi H, Nagamine T, Shimoda K, Ide S, Igarashi Y, Yoshioka I, Matumoto M.Single radial hemolysis (SRH), neutralization (NT), and hemagglutination inhibition (HI) tests were carried out on sera from horses immunized against the Prague and Miami strains of equine influenza virus. The HI and NT tests demonstrated good sensitivity; the sensitivity of the SRH test was somewhat lower. The NT titers of individual sera were correlated very closely with the HI titers, although the NT titers were higher. SRH zone diameters of individual sera also showed significant correlation with the NT and NI titers. The SRH test appears to be suitable for large-scale serological surveys ...
Turner S, Knych HK, Adams AA.Cannabidiol (CBD) has potential to reduce pain and inflammation in humans leading to the interest of use in equine. The purpose of this study was to determine the effects of CBD on immune function by measuring inflammatory cytokines and antibody responses to vaccination, as well as other health parameters in senior horses. Horses were orally-dosed with CBD (2 mg/kg: 13 horses) or control (soy oil: 14 horses) daily for 90 days, from July 2021 to November 2021. Peripheral blood samples were collected on days 0, 30, 60, and 90 before administering treatments. On day 90 all horses were kept on tr...
Reemers S, Sonnemans D, Horspool L, van Bommel S, Cao Q, van de Zande S.Vaccination is an effective tool to limit equine influenza virus (EIV H3N8) infection, a contagious respiratory disease with potentially huge economic impact. The study assessed the effects of antigenic change on vaccine efficacy and the need for strain update. Horses were vaccinated (V1 and V2) with an ISCOMatrix-adjuvanted, whole inactivated virus vaccine (Equilis Prequenza, group 2, FC1 and European strains) or a carbomer-adjuvanted, modified vector vaccine (ProteqFlu, group 3, FC1 and FC2 HA genes). Serology (SRH, HI, VN), clinical signs and viral shedding were assessed in comparison to un...
Nemoto M, Ohta M, Yamanaka T, Kambayashi Y, Bannai H, Tsujimura K, Yamayoshi S, Kawaoka Y, Cullinane A.From late 2018 to 2019, equine influenza virus (EIV) strains of Florida sublineage clade 1 (Fc1), which had until then been circulating mainly in the United States, suddenly spread across Europe causing many outbreaks, and Florida sublineage clade 2 (Fc2) strains, which had been circulating mainly in Europe, have not been detected in Europe since 2018. Since 2010, the World Organisation for Animal Health (OIE) has recommended that EIV vaccines contain an Fc1 strain that is like A/equine/South Africa/4/2003 or A/equine/Ohio/2003. Accordingly, Japanese vaccines contain A/equine/Ibaraki/1/2007 as...
Castro ER, Perez R, Rodriguez S, Bassetti L, Negro R, Vidal R.Equine influenza is one of the major respiratory infectious diseases in horses. In 2018, equine influenza virus (EIV) was confirmed as the cause of outbreaks of respiratory disease in horses in Chile and Argentina. In the same year, for the first time in Uruguay, EIV infection was confirmed by isolation and molecular analysis to be the cause of respiratory disease among hundreds of clinically affected thoroughbred horses in training and racing facilities. The virus was detected in nasopharyngeal swabs by a pan-reactive influenza type A realtime reverse transcription polymerase chain reaction (...
Wood JM, Mumford J, Schild GC, Webster RG, Nicholson KG.Single-radial-immunodiffusion (SRD) provides a sensitive and reproducible in vitro assay for haemagglutinin (HA) concentration in inactivated influenza vaccines. The use of SRD for human influenza vaccine standardization and application for equine and avian influenza vaccines is discussed. In clinical trials, vaccine HA concentration measured by SRD has been shown to be directly related to antibody responses and to protection against challenge. The use of SRD may considerably reduce the usage of animals for potency testing of veterinary influenza vaccines.
The Journal of hygieneJune 1, 1983
Volume 90, Issue 3 371-384 doi: 10.1017/s0022172400029004
Wood JM, Mumford J, Folkers C, Scott AM, Schild GC.Serological responses to three bivalent aqueous equine influenza vaccines of different potency and an adjuvanted bivalent vaccine containing inactivated A/equine/Prague/56 (H7N7) and A/equine/Miami/63 (H3N8) viruses, were examined in seronegative ponies. Potencies of the vaccines, measured by single-radial-diffusion tests, ranged from 4 to 56 micrograms of haemagglutinin (HA) antigen activity/virus strain per dose. Serological responses to vaccination were examined by haemagglutination-inhibition (HI) and single-radial-haemolysis (SRH) tests. Four weeks after a primary dose, HI responses to bo...
