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.
Back H, Weld J, Walsh C, Cullinane A.The aim of this study was to identify respiratory viruses circulating amongst elite racehorses in a training yard by serological testing of serial samples and to determine their impact on health status and ability to race. A six-month longitudinal study was conducted in 30 Thoroughbred racehorses (21 two-year-olds, five three-year-olds and four four-year-olds) during the Flat racing season. Sera were tested for the presence of antibodies against equine herpesvirus 1 and 4 (EHV-1 and EHV-4) and equine rhinitis viruses A and B (ERAV and ERBV) by complement fixation (CF) and equine arteritis viru...
Blanco-Lobo P, Rodriguez L, Reedy S, Oladunni FS, Nogales A, Murcia PR, Chambers TM, Martinez-Sobrido L.Vaccination remains the most effective approach for preventing and controlling equine influenza virus (EIV) in horses. However, the ongoing evolution of EIV has increased the genetic and antigenic differences between currently available vaccines and circulating strains, resulting in suboptimal vaccine efficacy. As recommended by the World Organization for Animal Health (OIE), the inclusion of representative strains from clade 1 and clade 2 Florida sublineages of EIV in vaccines may maximize the protection against presently circulating viral strains. In this study, we used reverse genetics tech...
Olguin-Perglione C, Vissani MA, Alamos F, Tordoya MS, Barrandeguy M.Equine influenza is an important cause of respiratory disease of horses worldwide. The equine influenza virus (EIV) undergoes antigenic drift through the accumulation of amino acid substitutions in the viral proteins, which may lead to vaccine breakdown. Objective: To describe the epidemiological findings and the molecular characteristics of the EIV detected during the multifocal outbreak that occurred in Argentina between March and July 2018 and evidence a vaccine breakdown. Methods: Observational, descriptive study. Methods: Virus was detected in nasopharyngeal swabs using real-time reverse ...
Nemoto M, Tamura N, Bannai H, Tsujimura K, Kokado H, Ohta M, Yamanaka T.Baloxavir marboxil (BXM), an inhibitor of the cap-dependent endonuclease of the influenza virus polymerase acidic protein (PA), exerts an antiviral effect against influenza A virus. It has been available in Japan since March 2018. This study evaluated the antiviral efficacy of BXM against equine influenza A virus (EIV) by an experimental challenge study using horses. Six horses were experimentally inoculated with EIV, and BXM was administered to the three horses at 2 days post inoculation. Horses treated with BXM showed milder clinical signs than horses without treatment and shed less virus. T...
With outbreaks of equine influenza continuing to be reported in the UK, Richard Newton and Fleur Whitlock of the Animal Health Trust discusses practical steps that vets can promote and practise to reduce the risk of the virus spreading.
Nemoto M, Yamayoshi S, Bannai H, Tsujimura K, Kokado H, Kawaoka Y, Yamanaka T.Equine influenza virus is an important pathogen for the horse industry because of its economic impact, and vaccination is a key control measure. Our previous work suggested that a mutation at position 144 in the hemagglutinin of Florida sublineage clade 2 viruses reduces the cross-neutralizing activity of antiserum against a former vaccine strain. To confirm this suggestion, here, we generated viruses by reverse genetics. Antibody titers against the mutated viruses were one-tenth to one-sixteenth of those against the former vaccine strain. Our findings confirm that this single amino acid subst...
Toh X, Soh ML, Ng MK, Yap SC, Harith N, Fernandez CJ, Huangfu T.Equine influenza is a major cause of respiratory infections in horses and can spread rapidly despite the availability of commercial vaccines. In this study, we carried out molecular characterization of Equine Influenza Virus (EIV) isolated from the Malaysian outbreak in 2015 by sequencing of the HA and NA gene segments using Sanger sequencing. The nucleotide and amino acid sequences of HA and NA were compared with representative Florida clade 1 and clade 2 strains using phylogenetic analysis. The Florida clade 1 viruses identified in this outbreak revealed numerous amino acid substitutions in ...
Gahan J, Garvey M, Asmah Abd Samad R, Cullinane A.In August 2015, Malaysia experienced an outbreak of acute respiratory disease in racehorses. Clinical signs observed were consistent with equine influenza (EI) infection. The index cases were horses recently imported from New Zealand. Rapid control measures, including temporary cancellation of racing, were implemented to minimize the impact of the outbreak. By November, the disease outbreak was resolved, and movement restrictions were lifted. The aim of this study was to confirm the clinical diagnosis and characterize the causal virus. A pan-reactive influenza type A real-time RT-PCR was used ...
Dam Van P, Desmecht D, Garigliany MM, Bui Tran Anh D, Van Laere AS.Type I/III interferons provide powerful and universal innate intracellular defense mechanisms against viruses. Among the antiviral effectors induced, Mx proteins of some species appear as key components of defense against influenza A viruses. It is expected that such an antiviral protein must display a platform dedicated to the recognition of said viruses. In an attempt to identify such platform in human MxA, an evolution-guided approach capitalizing on the antagonistic arms race between MxA and its viral targets and the genomic signature it left on primate genomes revealed that the surface-ex...
Pusterla N, James K, Mapes S, Bain F.Due to the inconsistent development of enteric signs associated with ECoV infection in adult horses, many practitioners collect nasal secretions rather than feces for the molecular diagnostic work-up of such horses. ECoV infection should be considered in horses presenting with acute onset of fever, especially when nasal discharge is absent as one of the cardinal clinical sign. A total of 277 adult horses with acute onset of fever were enrolled in this study. Feces were tested for ECoV and nasal secretions for common respiratory pathogens (equine herpesvirus (EHV)-1, EHV-4, equine influenza vir...
Milwid RM, O'Sullivan TL, Poljak Z, Laskowski M, Greer AL.Disease transmission models often assume homogenous mixing. This assumption, however, has the potential to misrepresent the disease dynamics for populations in which contact patterns are non-random. A disease transmission model with an SEIR structure was used to compare the effect of weighted and unweighted empirical equine contact networks to weighted and unweighted theoretical networks generated using random mixing. Equine influenza was used as a case study. Incidence curves generated with the unweighted empirical networks were similar in epidemic duration (5-8 days) and peak incidence (30.8...
Brister H, Barnum SM, Reedy S, Chambers TM, Pusterla N.We validated 2 multiplex real-time PCR (rtPCR) assays based on single nucleotide polymorphisms (SNPs) of the hemagglutinin-1 ( HA1) gene of H3N8 equine influenza A virus (EIV) to determine clade affiliation of prototype and field isolates. Initial validation of the 2 multiplex rtPCR assays (SNP1 and SNP2) was performed using nucleic acid from 14 EIV Florida sublineage clade 1 and 2 prototype strains. We included in our study previously banked EIV rtPCR-positive nasal secretions from 341 horses collected across the United States in 2012-2017 to determine their clade affiliation. All 14 EIV prot...
Rosanowski SM, Carpenter TE, Adamson D, Rogers CW, Pearce P, Burns M, Cogger N.Equine influenza (EI) is an infectious respiratory disease of horses that has never been reported in New Zealand (NZ). However, the 2007 EI outbreak in Australia, previously EI free, spurred the NZ government and stakeholders into evaluating alternative EI control strategies in order to economically justify any future decision to eradicate or manage EI. To build on the policy debate, this paper presents an epinomic (epidemiologic and economic) modelling approach to evaluate alternative control strategies. An epidemiologic model to determine how alternative EI control strategies influence the d...
Dilai M, Piro M, El Harrak M, Fougerolle S, Dehhaoui M, Dikrallah A, Legrand L, Paillot R, Fassi Fihri O.To evaluate the humoral immune response to mixed Equine Influenza vaccination, a common practice in the field, an experimental study was carried out on 42 unvaccinated thoroughbred weanling foals divided into six groups of seven. Three groups were vaccinated using a non-mixed protocol (Equilis Prequenza-Te, Proteqflu-Te or Calvenza-03) and three other groups were vaccinated using a mix of the three vaccines mentioned previously. Each weanling underwent a primary EI vaccination schedule composed of two primary immunisations (V1 and V2) four weeks apart followed by a third boost immunisation (V3...
Ghoniem SM, El Deeb AH, Aggour MG, Hussein HA.We developed a multiplex reverse-transcription real-time PCR (RT-rtPCR) assay for the simultaneous detection of the main equine respiratory viruses: equid alphaherpesviruses 1 and 4 (EHV-1, -4) and equine influenza virus (EIV; species Influenza A virus). The primers and probes amplified only the targeted viruses, and there were no inter-assay cross-amplifications or nonspecific interactions. The multiplex assay efficiencies were 92.5%, 97%, and 90% for EHV-1, EHV-4, and EIV, respectively. The R values of the monoplex and multiplex assays were ⩾0.990, and the slopes were -3.37 to -3.59. The p...
Singh RK, Dhama K, Karthik K, Khandia R, Munjal A, Khurana SK, Chakraborty S, Malik YS, Virmani N, Singh R, Tripathi BN, Munir M, van der Kolk JH.Among all the emerging and re-emerging animal diseases, influenza group is the prototype member associated with severe respiratory infections in wide host species. Wherein, Equine influenza (EI) is the main cause of respiratory illness in equines across globe and is caused by equine influenza A virus (EIV-A) which has impacted the equine industry internationally due to high morbidity and marginal morality. The virus transmits easily by direct contact and inhalation making its spread global and leaving only limited areas untouched. Hitherto reports confirm that this virus crosses the species ba...
Kumar B, Manuja A, Gulati BR, Virmani N, Tripathi BN.Zoonotic diseases are the infectious diseases that can be transmitted to human beings and vice versa from animals either directly or indirectly. These diseases can be caused by a range of organisms including bacteria, parasites, viruses and fungi. Viral diseases are highly infectious and capable of causing pandemics as evidenced by outbreaks of diseases like Ebola, Middle East Respiratory Syndrome, West Nile, SARS-Corona, Nipah, Hendra, Avian influenza and Swine influenza. Unassigned: Many viruses affecting equines are also important human pathogens. Diseases like Eastern equine encephalitis (...
Favaro PF, Reischak D, Brandao PE, Villalobos EMC, Cunha EMS, Lara MCC, Benvenga GU, Dias RA, Mori E, Richtzenhain LJ.The equine influenza virus (EIV) H3N8 subtype is responsible for all EIV outbreaks worldwide while the H7N7 subtype is less pathogenic and is considered extinct as it has not been confirmed in outbreaks since 1980. Although EIV is enzootic in Brazil, few reports describe the actual EIV antibody status in the country. The aims of this study were: - to evaluate the efficiency of different serum treatments described by the World Organisation for Animal Health (OIE) and the World Health Organization (WHO) to remove non-specific haemagglutination inhibitors for the haemagglutination inhibition (HI)...
Mucha V, Hollý J, Varečková E, Kostolanský F.Avian influenza A viruses (IAVs) are able to overcome the interspecies barrier and adapt to the new non-avian host. The process of adaptation requires the adaptive changes of IAV genome resulting in amino acid substitutions. The aim of this work was the description of amino acid substitutions in avian influenza A viruses (IAVs) occurring during their adaptation to equine host. Today, viruses of the equine influenza H3N8 subtype, first isolated in 1963, represent a single genetic lineage of IAV causing a respiratory disease in horses. We compared the amino acid sequences of the conserve...
Hemida MG, Perera RAPM, Chu DKW, Alnaeem AA, Peiris M.Equine influenza virus (EIV) is one of the main causes of viral respiratory affections in horses. Little is known about the prevalence of EIV in Saudi Arabia especially the H3N8 serotype. Objective: To assess prevalence of equine influenza in horse populations in Eastern and Central Saudi Arabia. Methods: Cross-sectional study. Methods: We collected 145 sera, 323 nasal and 323 rectal swabs from horses from six major cities in Eastern and Central regions. None of the horses were vaccinated against EIV. Sera were tested in ELISA assays for influenza A type-specific antibodies and by haemagglutin...
Dilai M, Piro M, Fougerolle S, El Harrak M, Mahir W, El Mourid R, Legrand L, Paillot R, Fassi Fihri O.In order to evaluate the vaccination status against equine influenza (EI) in Moroccan racehorses, a serological investigation was carried out on 509 racehorses using three serological tests: an Enzyme-Linked Immunosorbent Assay (ELISA), the Hemagglutination Inhibition (HI) test and the Single Radial Haemolysis (SRH) assay. The serological analysis showed 56% of seropositivity by ELISA, 67% by HI and 89.4% by SRH (with 69.9% above the clinical protection threshold). Using the Kappa test, the SRH and HI assays showed a strong agreement, the SRH and ELISA assays had a moderate agreement and the H...
Paillot R, Garrett D, Lopez-Alvarez MR, Birand I, Montesso F, Horspool L.Vaccination is one of the most effective tools for limiting the impact of equine influenza (EI). The humoral immunity established following a primary vaccination course can decrease significantly between the second (V2) and third immunisations (V3), leaving some horses insufficiently protected for several weeks. This so-called "immunity gap" poses a challenge to all EI vaccines. During this period, the EI infection of vaccinated animals may be followed by marked clinical signs and virus shedding. However, several EI vaccines have been shown to stimulate equine influenza virus (EIV)-specific ce...
Burashev Y, Strochkov V, Sultankulova K, Orynbayev M, Sansyzbay A, Sandybayev N, Nurabayev S, Savitskaya I, Rock DL, Tulman ER.Here, we report the complete genome sequencing of strains A/equine/Kostanay/9/2012(H3N8) and A/equine/LKZ/9/2012(H3N8) of the equine influenza virus belonging to Florida sublineage, clade 2. The strains were isolated in 2012 in the northern and southern regions of Kazakhstan, respectively.
, and of the equine influenza group at the Animal Health Trust provide a timely reminder of risk of equine influenza and the importance of vaccination.
Laing G, Christley R, Stringer A, Aklilu N, Ashine T, Newton R, Radford A, Pinchbeck G.Pathogens are frequently implicated in equine respiratory disease. In Ethiopia, respiratory disease is a frequent cause for presentation at veterinary clinics and a priority concern for users of working horses. However, there is little existing literature on possible aetiologies. Objective: Determine prevalence of respiratory signs and exposure to major respiratory pathogens through a serological survey. Methods: Cross-sectional. Methods: Systematically selected horses from 19 sites in central Ethiopia were examined clinically and sampled once (August-December 2013). A face-to-face interview c...
Smith FL, Watson JL, Spier SJ, Kilcoyne I, Mapes S, Sonder C, Pusterla N.Imported horses that have undergone recent long distance transport might represent a serious risk for spreading infectious respiratory pathogens into populations of horses. Objective: To investigate the frequency of shedding of respiratory pathogens in recently imported horses. Methods: All imported horses with signed owner consent (n = 167) entering a USDA quarantine for contagious equine metritis from October 2014 to June 2016 were enrolled in the study. Methods: Prospective observational study. Enrolled horses had a physical examination performed and nasal secretions collected at the ti...
Spence KL, O'Sullivan TL, Poljak Z, Greer AL.On-farm biosecurity measures are an important part of a control plan to minimize the introduction and spread of infectious diseases, such as equine influenza, in an equine facility. It can be challenging, however, to evaluate the efficacy of biosecurity measures under field conditions. We used an agent-based computer simulation model to describe the impact of: i) preventive vaccination; ii) reduced horse-to-horse contact; and iii) a combination of vaccination and reduced contact during an outbreak of equine influenza in a simulated horse facility. The model demonstrated that the most effective...
Quinlivan M, Dempsey E, Ryan F, Arkins S, Cullinane A.Equine influenza is a cause of epizootic respiratory disease of the equine. The detection of equine influenza virus using real-time Light Cycler reverse transcription (RT)-PCR technology was evaluated over two influenza seasons with the analysis of 171 samples submitted for viral respiratory disease. Increased sensitivity was found in overall viral detection with this system compared to Directigen Flu A and virus isolation, which were 40% and 23%, respectively, that of the RT-PCR. The assay was also evaluated as a viable replacement for the more traditional methods of quantifying equine influe...
Paillot R, El-Hage CM.In 2007, Australia experienced the most extensive equine influenza outbreak observed in recent years. Extraordinary measures were rapidly implemented in order to control and prevent the spread of this highly contagious disease. The control strategy involved stringent movement restriction and disease surveillance, seconded by emergency post-outbreak vaccination strategies. Sixteen months after the first case and 12 months following the last reported case, Australia regained its equine influenza-free OIE status. This systematic review reports and summarises information relating to the implementa...
Cullinane A, Weld J, Osborne M, Nelly M, Mcbride C, Walsh C.The purpose of these studies was to examine the response of Thoroughbred foals and yearlings to different influenza vaccines and vaccination regimes. The horses' antibody levels against haemagglutinin, an established correlate of protection were measured by haemagglutination inhibition. The first study investigated the extent to which maternal antibodies interfered with the humoral response to a subunit vaccine. The findings suggest that repeat vaccination in the face of maternal antibodies may induce tolerance as defined by serological testing. The second study compared the immune response el...
Chambers TM, Holland RE, Tudor LR, Townsend HG, Cook A, Bogdan J, Lunn DP, Hussey S, Whitaker-Dowling P, Youngner JS, Sebring RW, Penner SJ....Flu Avert IN vaccine is a new, live attenuated virus vaccine for equine influenza. We tested this vaccine in vivo to ascertain 1) its safety and stability when subjected to serial horse to horse passage, 2) whether it spread spontaneously from horse to horse and 3) its ability to protect against heterologous equine influenza challenge viruses of epidemiological relevance. For the stability study, the vaccine was administered to 5 ponies. Nasal swabs were collected and pooled fluids administered directly to 4 successive groups of naïve ponies by intranasal inoculation. Viruses isolated from th...
Tumova B, Easterday BC.This study demonstrates relationships in envelope antigens of 4 human influenza A2 strains isolated during the period 1957-68 (including A2/Hong Kong/68), 2 strains of A/Equi-2/63 and 7 avian influenza viruses isolated in Europe, North America, and the Ukraine in the years 1960-67.Antigenic relationships among the strains were determined on the basis of haemagglutination-inhibition, virus-neutralization, strain-specific complement-fixation, and neuraminidase-inhibition tests.North American avian influenza strains, Turkey/California/64, Turkey/Massachusetts/65, Turkey/Wisconsin/66, Turkey/Ontar...
Yang H, Xiao Y, Meng F, Sun F, Chen M, Cheng Z, Chen Y, Liu S, Chen H.Equine influenza virus is a major respiratory pathogen in horses. Although both horses and donkeys belong to the genus Equus, donkey infection with influenza viruses is rare. In March 2017, an influenza outbreak occurred in donkeys in Shandong province, China. The causative virus, A/donkey/Shandong/1/2017(H3N8), was isolated from a dead donkey. Genetic analysis indicated that the virus originated from influenza A (H3N8) clade 2 of the Florida sub-lineage that has been circulating in Asian equine populations. Comparison of the deduced amino acid sequence of the HA gene of this causative virus w...
Wilson WD.Influenza continues to be one of the most important diseases of horses despite the availability and widespread use of equine influenza vaccines for almost 30 years. In recent years, infection with the influenza A/equine/2 subtype has become endemic in the equine populations of North America, Europe, and Scandinavia. Continued antigenic drift of field virus has compromised the efficacy of vaccines, most of which contain antigens prepared from influenza viruses isolated more than 10 years ago. This article reviews the history, virology, epidemiology, pathogenesis, immunology, clinical presentati...
Garner MG, Cowled B, East IJ, Moloney BJ, Kung NY.In August 2007, Australia which had previously been free of equine influenza, experienced a large outbreak that lasted approximately 4 months before it was eradicated. The outbreak required a significant national response by government and the horse industries. The main components of the response were movement controls, biosecurity measures, risk-based zoning and, subsequently, vaccination to contain the outbreak. Although not initially used, vaccination became a key element in the eradication program, with approximately 140000 horses vaccinated. Vaccination is recognised as a valuable tool fo...
Perglione CO, Gildea S, Rimondi A, Miño S, Vissani A, Carossino M, Cullinane A, Barrandeguy M.In 2012, equine influenza (EI) virus was confirmed as the cause of outbreaks of respiratory disease in horses throughout South America. In Uruguay and Argentina, hundreds of vaccinated thoroughbred horses in training and racing facilities were clinically affected. Objective: To characterise the EI viruses detected during the outbreak in Uruguay and Argentina. Methods: Virus was detected in nasopharyngeal swabs by a pan-reactive influenza type A real-time RT-PCR. The nucleotide sequence of the HA1 gene was determined and analysed phylogenetically using mega 5 software. Amino acid sequences alig...
Guo Y, Wang M, Zheng GS, Li WK, Kawaoka Y, Webster RG.In May 1993, a severe epidemic of respiratory disease began in horses in Inner Mongolia and spread throughout horses in China. The disease affected mules and donkeys as well as horses but did not spread to other species, including humans. The severity of the disease raised the question of whether the outbreak might have been caused by the new avian-like influenza viruses detected in horses in China in 1989 or by current variants ofA/equine/Miami/1/63 (H3N8) (equine-2) or by a reassortant between these viruses. Antigenic and sequence analysis established that all gene segments of the influenza ...
Paillot R, Grimmett H, Elton D, Daly JM.In the horse, conventional inactivated or subunit vaccines against equine influenza virus (EIV) induce a short-lived antibody-based immunity to infection. Alternative strategies of vaccination have been subsequently developed to mimic the long-term protection induced by natural infection with the virus. One of these approaches is the use of immune-stimulating complex (ISCOM)-based vaccines. ISCOM vaccines induce a strong antibody response and protection against influenza in horses, humans, and a mouse model. Cell-mediated immunity (CMI) has been demonstrated in humans and mice after ISCOM vacc...
Hoffman AM, Viel L, Prescott JF, Rosendal S, Thorsen J.Undifferentiated distal respiratory tract disease (nasal discharge, cough, pneumonia) in foals (1 to 8 months old) is a burdensome economic problem on breeding farms; yet, the infective agents associated with these episodes have not been well described. Possible causes of these episodes of illness were investigated by culturing specimens of proximal and distal airways of clinically diseased foals (n = 101), prior to any treatment, for aerobic and anaerobic bacteria and viruses (rhinoviruses, equine arteritis virus, equine herpesvirus subtype 1 [EHV-1], influenza virus, and adenovirus). Pairs o...
Lin C, Holland RE, Donofrio JC, McCoy MH, Tudor LR, Chambers TM.Equine influenza virus (EIV) is the leading cause of acute respiratory infection in horses worldwide. In recent years, the precise mechanism by which influenza infection kills host cells is being re-evaluated. In this report, we examined whether caspases, a group of intracellular proteases, are activated following EIV infection and contribute to EIV-mediated cell death. Western blotting analysis indicated that a nuclear target of caspase-3, poly(ADP-ribose) polymerase (PARP) was proteolytically cleaved in EIV-infected MDCK cells, but not in mock-infected cells. In comparison with caspase-3 spe...
Ochoa M, Bárcena J, de la Luna S, Melero JA, Douglas AR, Nieto A, Ortín J, Skehel JJ, Portela A.Characterization of the epitopes recognized by 21 monoclonal antibodies (MAbs) specific for the influenza A virus PA (13 MAbs) and PB2 (8 MAbs) polypeptides (Bárcena et al. (1994) J. Virol. 68, 6900-6909) raised against denatured polypeptides produced in E. coli is described. MAbs were characterized by: (1) competitive binding ELISAs; (2) mapping of the protein regions that specify their binding sites; and (3) analyses of their ability to recognize the corresponding viral protein in a number of viral isolates. Five and three non-overlapping antigenic areas were defined by the anti-PA and anti...
Paillot R, Rash NL, Garrett D, Prowse-Davis L, Montesso F, Cullinane A, Lemaitre L, Thibault JC, Wittreck S, Dancer A.Vaccination is highly effective to prevent, control, and limit the impact of equine influenza (EI), a major respiratory disease of horses. However, EI vaccines should contain relevant equine influenza virus (EIV) strains for optimal protection. The OIE expert surveillance panel annually reviews EIV evolution and, since 2010, the use of Florida clade 1 and 2 sub-lineages representative vaccine strains is recommended. This report summarises the development process of a fully- updated recombinant canarypox-based EI vaccine in order to meet the last OIE recommendations, including the vaccine mode ...
Smith FL, Watson JL, Spier SJ, Kilcoyne I, Mapes S, Sonder C, Pusterla N.Imported horses that have undergone recent long distance transport might represent a serious risk for spreading infectious respiratory pathogens into populations of horses. Objective: To investigate the frequency of shedding of respiratory pathogens in recently imported horses. Methods: All imported horses with signed owner consent (n = 167) entering a USDA quarantine for contagious equine metritis from October 2014 to June 2016 were enrolled in the study. Methods: Prospective observational study. Enrolled horses had a physical examination performed and nasal secretions collected at the ti...
Barbic L, Madic J, Turk N, Daly J.In April 2004 an outbreak of equine influenza occurred at the Zagreb hippodrome, Croatia. Clinical respiratory disease of the same intensity was recorded in vaccinated and non-vaccinated horses. The equine influenza vaccine used in Croatia at the time of the outbreak contained the strains A/equine/Miami/63 (H3N8), A/equine/Fontainebleau/79 (H3N8) and A/equine/Prague/56 (H7N7). At the same time, the usual strains in vaccines used in Europe were, in accordance with the recommendation of the World Organisation for Animal Health (OIE) Expert Surveillance Panel on equine influenza, A/equine/Newmark...
Wattrang E, Jessett DM, Yates P, Fuxler L, Hannant D.The production of interferon (IFN), interleukin-6 (IL-6), and tumor necrosis factor (TNF) was monitored in horses during the course of influenza A2 virus infections. The effects of two virus strains, Newmarket/2/93 and Sussex/89, were compared, of which the latter is considered the more pathogenic in terms of clinical signs. Ten naive ponies were infected with influenza A/equine/Sussex/89 and 10 with influenza A/equine/Newmarket/2/93, respectively. As expected ponies infected with Sussex/89 showed the most pronounced clinical signs but there was no notable difference in viral excretion compare...
Ito M, Nagai M, Hayakawa Y, Komae H, Murakami N, Yotsuya S, Asakura S, Sakoda Y, Kida H.In August 2007, an outbreak of equine influenza occurred among vaccinated racehorses with Japanese commercial equine influenza vaccine at Kanazawa Racecourse in Ishikawa prefecture in Japan. Apparent symptoms were pyrexia (38.2-41.0 degrees C) and nasal discharge with or without coughing, although approximately half of the infected horses were subclinical. All horses had been shot with a vaccine that contained two inactivated H3N8 influenza virus strains [A/equine/La Plata/93 (La Plata/93) of American lineage and A/equine/Avesta/93 (Avesta/93) of European lineage] and an H7N7 strain (A/equine/...
Daniels RS, Skehel JJ, Wiley DC.The amino acid sequence of the haemagglutinin of A/equine/Miami/63 (H3N8), the prototype influenza virus of the H3 subtype from horses, is deduced from the nucleotide sequence of virus RNA and compared with the sequences of haemagglutinins of viruses of this subtype isolated from humans [X-31 (H3N2)] and from birds [A/duck/Ukraine/63 (H3N8)] and with the sequence of the haemagglutinin of A/equine/Fontainebleau/79 (H3N8) a virus isolated from a recent outbreak of equine influenza. The amino acid sequence differences detected are discussed with reference to the structure of the molecules, their ...
Lunn DP, Soboll G, Schram BR, Quass J, McGregor MW, Drape RJ, Macklin MD, McCabe DE, Swain WF, Olsen CW.Equine influenza virus infection remains one of the most important infectious diseases of the horse, yet current vaccines offer only limited protection. The equine immune response to natural influenza virus infection results in long-term protective immunity, and is characterized by mucosal IgA and serum IgGa and IgGb antibody responses. DNA vaccination offers a radical alternative to conventional vaccines, with the potential to generate the same protective immune responses seen following viral infection. Antigen-specific antibody isotype responses in serum and mucosal secretions were studied i...
Lu Z, Chambers TM, Boliar S, Branscum AJ, Sturgill TL, Timoney PJ, Reedy SE, Tudor LR, Dubovi EJ, Vickers ML, Sells S, Balasuriya UB.The objective of this study was to develop and evaluate new TaqMan real-time reverse transcription-PCR (rRT-PCR) assays by the use of the minor groove binding probe to detect a wide range of equine influenza virus (EIV) strains comprising both subtypes of the virus (H3N8 and H7N7). A total of eight rRT-PCR assays were developed, targeting the nucleoprotein (NP), matrix (M), and hemagglutinin (HA) genes of the two EIV subtypes. None of the eight assays cross-reacted with any of the other known equine respiratory viruses. Three rRT-PCR assays (EqFlu NP, M, and HA3) which can detect strains of th...
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...
Yates P, Mumford JA.To investigate the level of cross-protection induced by equine influenza H3N8 vaccines derived from different lineages, two studies have been carried out with ponies vaccinated with 'American-like' and 'European-like' vaccines and experimentally challenged with a European-like strain. The results demonstrated that equine influenza vaccines clearly protect against challenge with homologous virus if serum antibody titres are sufficiently high. On the other hand, protection is incomplete even when animals vaccinated with heterologous strains have comparative antibody levels. Nevertheless, the pro...
Quinlivan M, Nelly M, Prendergast M, Breathnach C, Horohov D, Arkins S, Chiang YW, Chu HJ, Ng T, Cullinane A.Most studies of the cytokine response to influenza virus infection have been carried out in human, porcine and murine models, however the data available on equine cytokines is limited. An experimental challenge study was undertaken in unvaccinated naïve horses and horses vaccinated with a commercial inactivated influenza vaccine. The humoral antibody response to vaccination and virus challenge was measured by single radial haemolysis (SRH) assay and clinical signs of influenza and viral shedding were monitored post-challenge. Levels of three equine pro-inflammatory cytokines interleukin (IL)-...
Mumford JA, Jessett DM, Rollinson EA, Hannant D, Draper ME.Seven previously untreated five-month-old New Forest ponies received two doses of equine influenza immunostimulating complex vaccines, one with and one without an immunopurified tetanus toxoid component, given by deep intramuscular injection six weeks apart, followed by a booster dose without tetanus toxoid five months later. Fifteen months after the third dose of vaccine, the ponies were challenged by exposure to an aerosol of influenza A/Equine 2/Sussex/89 (H3N8), a virus isolated from a recent outbreak of influenza A/equine 2 in Britain. The challenge produced severe clinical signs of influ...
Doubli-Bounoua N, Richard EA, Léon A, Pitel PH, Pronost S, Fortier G.The potential involvement of viruses in inflammatory airway disease (IAD) was previously investigated through either serology or PCR from nasopharyngeal swabs (NS). The aims of this study were to determine the prevalence and incidence of viral genome detection by qPCR in the equine airways, and their association with respiratory clinical signs. Both NS and tracheal washes (TW) were collected monthly on 52 Standardbred racehorses at training, over 27 consecutive months (581 samples). Equid herpesviruses (EHV)-1, -4, -2 and -5, equine rhinitis virus-A and -B (ERBV), equine adenovirus-1 and -2, e...
The Journal of hygieneJune 1, 1983
Volume 90, Issue 3 385-395 doi: 10.1017/s0022172400029016
Mumford J, Wood JM, Scott AM, Folkers C, Schild GC.Forty ponies immunized with inactivated virus vaccine containing A/equine/Miami/63 (H3N8) virus and six unvaccinated, seronegative ponies were experimentally challenged with a representative of recent equine H3N8 virus isolates, A/equine/Newmarket/79. All unvaccinated ponies became infected as judged by virus excretion, febrile responses and antibody responses, but only two of the vaccinated ponies were fully protected. Pre-challenge antibody levels to A/Newmarket/79 virus detected by single radial haemolysis (SRH) correlated well with the degree of clinical protection but the levels required ...
