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Topic:Vaccine
Vaccination in horses involves the administration of biological preparations designed to stimulate the equine immune system to recognize and combat specific pathogens. Vaccines are formulated to prevent or reduce the severity of infectious diseases that can affect equine health and performance. Common vaccines for horses include those for equine influenza, tetanus, equine herpesvirus, and West Nile virus. The administration schedule and type of vaccine can vary based on factors such as geographic location, age, and use of the horse. This page compiles peer-reviewed research studies and scholarly articles that explore the development, efficacy, and safety of vaccines in horses, as well as their impact on equine health management.
The effects of strain heterology on the epidemiology of equine influenza in a vaccinated population. We assess the effects of strain heterology (strains that are immunologically similar but not identical) on equine influenza in a vaccinated population. Using data relating to individual animals, for both homologous and heterologous vaccinees, we estimate distributions for the latent and infectious periods, quantify the risk of becoming infected in terms of the quantity of cross-reactive antibodies to a key surface protein of the virus (haemagglutinin) and estimate the probability of excreting virus (i.e. becoming infectious) given that infection has occurred. The data suggest that the infectio...
West Nile virus vaccines. West Nile virus (WNV) is a mosquito-borne flavivirus that is emerging as a global pathogen. In the last decade, virulent strains of the virus have been associated with significant outbreaks of human and animal disease in Europe, the Middle East and North America. Efforts to develop human and veterinary vaccines have taken both traditional and novel approaches. A formalin-inactivated whole virus vaccine has been approved for use in horses. DNA vaccines coding for the structural WNV proteins have also been assessed for veterinary use and have been found to be protective in mice, horses and birds...
Efficacy of a live equine herpesvirus-1 (EHV-1) strain C147 vaccine in foals with maternally-derived antibody: protection against EHV-1 infection. Currently, there is no recommended immunoprophylaxis against febrile respiratory diseases due to equine herpesvirus-1 (EHV-1) and -4 (EHV-4) in horses below age 5-6 months. This is because of interference by maternally-derived antibody (MDA) of vaccines. Objective: Unweaned equine foals are an important reservoir of EHV-1 transmission; therefore, we experimentally assessed the efficacy of a live EHV-1 vaccine in foals age 1.4-3.5 months with MDA. Methods: Following vaccination and challenge, parameters assessed were virus shedding in nasal mucus, leucocyte-associated viraemia, circulating viru...
Current perspectives on control of equine influenza. Influenza A viruses of the H3N8 subtype are a major cause of respiratory disease in horses. Subclinical infection with virus shedding can occur in vaccinated horses, particularly where there is a mismatch between the vaccine strains and the virus strains circulating in the field. Such infections contribute to the spread of the disease. Rapid diagnostic techniques are available for detection of virus antigen and can be used as an aid in control programmes. Improvements have been made to methods of standardising inactivated virus vaccines, and a direct relationship between vaccine potency measur...
DNA vaccines–back in the saddle again? A promising new horse vaccine may reignite enthusiasm for DNA vaccine technology in designing prophylactics against infectious disease. Kendall Powell reports.
Detection of EHV-1 and EHV-4 DNA in unweaned Thoroughbred foals from vaccinated mares on a large stud farm. A silent cycle of equine herpesvirus 1 infection has been described following epidemiological studies in unvaccinated mares and foals. In 1997, an inactivated whole virus EHV-1 and EHV-4 vaccine was released commercially in Australia and used on many stud farms. However, it was not known what effect vaccination might have on the cycle of infection of EHV-1. Objective: To investigate whether EHV-1 and EHV-4 could be detected in young foals from vaccinated mares. Methods: Nasal and blood samples were tested by PCR and ELISA after collection from 237 unvaccinated, unweaned foals and vaccinated an...
Evaluation of immune responses in horses immunized using a killed Sarcocystis neurona vaccine. Clinically normal horses developed cellular immunity to Sarcocystis neurona following IM vaccination with a commercial killed S. neurona vaccine, as indicated by the development of measurable anti-S. neurona IgG antibodies and additional intradermal skin testing. Large-scale independent assessments of the vaccine's performance and safety are in progress under field conditions. The next step in the evaluation of this vaccine would be to attempt experimental challenge after a reproducible reliable equine model of S. neurona encephalitis has been established that allows for reisolation of the pat...
Serologic responses to eastern and western equine encephalomyelitis vaccination in previously vaccinated horses. A prospective study was performed to determine the serologic response of previously vaccinated horses to revaccination against eastern and western equine encephalomyelitis (EEE and WEE). Horses responded variably to each antigen, and some horses had low or undetectable antibodies 6 months after vaccination. Some horses did not develop increasing titers to EEE or WEE despite recent vaccination. Geometric mean titers peaked 2 weeks after revaccination and were significantly increased from before revaccination. Except for one horse, EEE:WEE titer ratios ranged from 0.25 to 2.0. Regular vaccinatio...
Recombinant canarypoxvirus vaccine carrying the prM/E genes of West Nile virus protects horses against a West Nile virus-mosquito challenge. An ALVAC (canarypoxvirus)-based recombinant (vCP2017) expressing the prM and E genes derived from a 1999 New York isolate of West Nile virus (WNV) was constructed and assessed for its protective efficacy in horses in two different experiments. In the first trial, a dose titration study was conducted to evaluate both serum neutralising antibody responses to WNV and duration of immunity. In the second trial the onset of protection was determined. Twenty-eight adult horses received two doses of vCP2017 administered intramuscularly at 5-week intervals and sixteen horses comprised age-matched non-v...
Seroprevalence of equine herpesvirus 1 in mares and foals on a large Hunter Valley stud farm in years pre- and postvaccination. To examine the prevalence of equine herpesvirus 1 antibody in mares and foals on a large Hunter Valley Thoroughbred stud farm in New South Wales before and after the introduction of an inactivated whole virus vaccine. Methods: Cross-sectional serological surveys performed in February 1995 and 2000 to determine the prevalence of EHV-1 antibody-positive mares and foals. A further cross-sectional survey was carried out in 2001 to complement the 2000 data. Methods: Two hundred and twenty-nine mares and their foals were sampled in 1995 and 236 mares and their foals were sampled in 2000. The study p...
Prevalence of antibody to Japanese encephalitis virus nonstructural 1 protein among racehorses in Japan: indication of natural infection and need for continuous vaccination. Japanese encephalitis virus (JEV) causes fatal diseases in equines as well as humans. In Japan, racehorses are vaccinated with inactivated JE vaccine every year and no equine JE cases have been reported since 1986. However, the current reduction in JEV activity in nature has raised an argument against the requirement of continuous vaccination. Here, we studied natural infection rates in racehorses to address the issue. To identify naturally-infected individuals from vaccinated populations, we used an immunostaining method for detecting antibodies to JEV nonstructural 1 (NS1) protein. A total o...
Efficacy and duration of immunity of a combined equine influenza and equine herpesvirus vaccine against challenge with an American-like equine influenza virus (A/equi-2/Kentucky/95). It has been recommended that modern equine influenza vaccines should contain an A/equi-1 strain and A/equi-2 strains of the American and European-like subtype. We describe here the efficacy of a modern updated inactivated equine influenza-herpesvirus combination vaccine against challenge with a recent American-like isolate of equine influenza (A/equine-2/Kentucky/95 (H3N8). The vaccine contains inactivated Influenza strains A-equine-1/Prague'56, A-equine-2/Newmarket-1/'93 (American lineage) and A-equine-2/ Newmarket-2/93 (Eurasian lineage) and inactivated EHV-1 strain RacH and EHV-4 strain V22...
Sarcocystis neurona-specific immunoglobulin G in the serum and cerebrospinal fluid of horses administered S neurona vaccine. A vaccine against Sarcocystis neurona, which induces equine protozoal myeloencephalitis (EPM), has received conditional licensure in the United States. A major concern is whether the immunoglobulin G (IgG) response elicited by the vaccine will compromise the use of Western blotting (WB) as a diagnostic tool in vaccinated horses with neurologic disease. Our goals were to determine if vaccination (1) causes seroconversion: (2) causes at least a transient increase in S neurona-specific IgG in the cerebrospinal fluid (CSF); and (3) induces an IgG response that can be differentiated from that induc...
Equine vaccine for West Nile virus. To meet the urgent need of controlling West Nile virus (WNV) infection in the equine population, we have developed a killed WNV vaccine. A dose titration study in horses was first conducted to evaluate serum neutralization antibody responses against WNV in these animals. Horses were vaccinated intramuscularly twice with the test vaccine at low, medium and high dose, three weeks apart. Serum samples were collected periodically and were measured for serum neutralizing antibody using a plaque reduction neutralization test. Significant increases in serum neutralizing antibody were detected in all ...
Lyme borreliosis. Despite more than 25 years' experience with Lyme borreliosis, much remains to be learned about this complex zoonosis. Practicing veterinarians, particularly those in the northeastern and upper midwestern states, where Lyme borreliosis is highly endemic, should be familiar with the ecologic features and typical clinical signs of Lyme borreliosis. Interpretation of signs and serologic test results should be made with consideration of the regional prevalence of Lyme borreliosis and the animal's opportunity for exposure to infected Ixodes spp. The availability of recently marketed topical acaracid...
Analysis of anamnestic immune responses in adult horses and priming in neonates induced by a DNA vaccine expressing the vapA gene of Rhodococcus equi. Rhodococcus equi remains one of the most important pathogens of early life in horses, yet conventional vaccines to prevent rhodococcal pneumonia have not been successful. DNA vaccination offers an alternative to conventional vaccines with specific advantages for immunization of neonates. We developed a DNA vaccine expressing the vapA gene (pVR1055vapA) that induced an anamnestic response characterized by virulence associated protein A (VapA)-specific IgG antibodies in sera and bronchoalveolar lavage fluid (BALF) as well as VapA-specific proliferation of pulmonary lymphocytes when tested in adu...
Comparison of hamster and pony challenge models for evaluation of effect of antigenic drift on cross protection afforded by equine influenza vaccines. Vaccination and challenge studies in ponies are the most relevant experimental system for predicting whether strains included in equine influenza vaccines are relevant, but they are difficult to perform. Objective: In order to investigate the feasibility of using a small animal model, results of a cross-protection study in hamsters were compared with those from a previous pony challenge experiment. Methods: Animals were immunised with inactivated vaccines containing one of 4 strains of equine influenza A H3N8 subtype virus isolated over a 26 year period (1963 to 1989), then challenged with a 1...
Regional antibody and cellular immune responses to equine influenza virus infection, and particle mediated DNA vaccination. We have previously demonstrated that hemagglutinin (HA) gene vaccination and influenza virus infection generate protective antibody responses in equids. However, these antibody responses differ substantially in that particle mediated DNA vaccination does not induce an immunoglobulin A (IgA) response. A study was performed to investigate the regional immunoregulatory mechanisms associated with these different immune responses. Ponies were either vaccinated with equine HA DNA vaccines at skin and mucosal sites, infected with influenza virus or left untreated and influenza-specific antibody respo...
West Nile virus encephalomyelitis in horses: 46 cases (2001). To determine signalment, clinical findings, results of diagnostic testing, outcome, and postmortem findings in horses with West Nile virus (WNV) encephalomyelitis. Methods: Retrospective study. Methods: 46 horses with WNV encephalomyelitis. Methods: Clinical data were extracted from medical records of affected horses. Results: On the basis of clinical signs and results of serologic testing, WNV encephalomyelitis was diagnosed in 46 of 56 horses with CNS signs. Significantly more males than females were affected. Increased rectal temperature, weakness or ataxia, and muscle fasciculations were t...
Limited potential for mosquito transmission of genetically engineered, live-attenuated western equine encephalitis virus vaccine candidates. Specific mutations associated with attenuation of Venezuelan equine encephalitis (VEE) virus in rodent models were identified during efforts to develop an improved VEE vaccine. Analogous mutations were produced in full-length cDNA clones of the Cba 87 strain of western equine encephalitis (WEE) virus by site-directed mutagenesis in an attempt to develop an improved WEE vaccine. Isogenic viral strains with these mutations were recovered after transfection of baby hamster kidney cells with infectious RNA. We evaluated two of these strains (WE2102 and WE2130) for their ability to replicate in and...
Venezuelan equine encephalitis virus-vectored vaccines protect mice against anthrax spore challenge. Anthrax, a disease usually associated with herbivores, is caused by the bacterium Bacillus anthracis. The current vaccine licensed for human use requires a six-dose primary series and yearly boosters and causes reactogenicity in up to 30% of vaccine recipients. A minimally reactogenic vaccine requiring fewer inoculations is warranted. Venezuelan equine encephalitis (VEE) virus has been configured for use as a vaccine vector for a wide variety of immunogens. The VEE vaccine vector is composed of a self-replicating RNA (replicon) containing all of the VEE virus nonstructural genes and a multiple...
Occurrence of infectious upper respiratory tract disease and response to vaccination in horses on six sentinel premises in northern Colorado. 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...
Equid herpesvirus (EHV-1) live vaccine strain C147: efficacy against respiratory diseases following EHV types 1 and 4 challenges. The temperature sensitive and host range mutant clone 147 of equine herpesvirus 1 (EHV-1) was assessed for its ability to protect conventional, susceptible adult horses against respiratory infection by EHV-1 and equine herpesvirus 4 (EHV-4). Intranasal (IN) vaccination with 5.2 log(10) TCID(50) did not cause adverse clinical reactions although a limited virus shedding and viraemia (leukocytes) was observed in 11 of 15 and 10 of 15 vaccinated horses respectively. All 15 vaccinated horses showed a significant seroresponse to both EHV-1 and EHV-4 for virus neutralising (VN) antibody. None of 14 c...
Derivation and characterisation of a live equid herpes virus-1 (EHV-1) vaccine to protect against abortion and respiratory disease due to EHV-1. A German abortion isolate of EHV-1 (strain M8) was grown in equine dermal (ED) cells at a low multiplicity of infection in presence of 5-bromo-2-deoxy uridine. The resulting stock was dialysed, titrated and cloned by terminal dilution in ED cells grown in 96-well microtitration plates. Of 192 clones each originating from a single focus, clone 147 (C147) was found to be restricted for growth at and above temperatures of 38.5 degrees C. It was also restricted for growth at 37 degrees C in rabbit kidney (RK-13) cells which are widely used for the isolation and titration of EHV-1; hence clone 147 ...
Stable and long-lasting immune response in horses after DNA vaccination against equine arteritis virus. Equine arteritis virus (EAV) is the causative agent of the equine viral arteritis. It is a small RNA virus with a linear, non-segmented plus RNA genome. EAV is a member of the Arteriviridae family that includes porcine reproductive and respiratory syndrome virus (PRSSV), simian haemorrhagic fever virus (SHFV) and lactate dehydrogenase virus (LDV). The viral transmission is via respiratory and reproductive routes. Clinical signs in horses vary, and severe infection can lead to abortions in pregnant mares or neonatal foal death. The aim of this study was to investigate the development of the imm...
Porcine zona pellucida (PZP) immunocontraception of wild horses (Equus caballus) in Nevada: a 10 year study. Porcine zona pellucida (PZP) immunocontraception was investigated for possible use in free-roaming wild horses in the western USA. A protocol of two injections (3-4 weeks apart) of vaccine lasting 1 year was first used and a single-injection controlled-release vaccine of 1 year duration was developed and tested in the field. Studies of a presumptive vaccine of 2 year duration were initiated. The parameters of anti-PZP antibody titre response, pregnancy testing and offspring production were used, and PZP vaccine was found to provide up to 94% infertility in free-roaming wild mares. In addition,...
Effects of immunocontraception on population, longevity and body condition in wild mares (Equus caballus). Contraception is becoming a common approach for the management of captive and wild ungulates yet there are few data for contraceptive effects on entire populations. Management-level treatment of mares with porcine zona pellucida (PZP) vaccine resulted in zero population growth of the Assateague Island wild horse population within 1 year of initiation of treatment. Contraceptive efficacy was 90% for mares treated twice in the first year and annually thereafter. For mares given a single initial inoculation, contraceptive efficacy was 78%. The effort required to achieve zero population growth dec...
