RESUMO
Equine influenza is a highly contagious viral disease, specially among 1-5 years old naive horses. Vaccination is considered the best way to control the disease spread and outbreaks. Although foals are the main animal used for evaluation of equine influenza vaccines, guinea pigs were chosen as an alternative model in the present work, as they have a negligible antibody titer against equine influenza virus and are cheaper and easier to handle than foals. Five equine influenza vaccine batches were evaluated in two animal models, foals and guinea pigs, by injection of two doses/animal with 4 weeks apart using 2 mL/animal/dose and evaluation of immune responses by hemagglutination inhibition test and enzyme-linked immunosorbent assay. On the 7th week post vaccination, equine influenza antibodies titers reached maximum values of 9-10.2 and 8.7-10 hemagglutination inhibition units for foals and guinea pigs, respectively; sample/negative ratios were 0.126-0.464 and 0.128-0.445 for both animals, respectively. The use of guinea pigs as an animal model for the evaluation of equine influenza vaccines could be recommended instead of foals(AU)
La gripe equina es una enfermedad viral muy contagiosa, especialmente entre los caballos jóvenes de 1 a 5 años de edad. La vacunación se considera la mejor forma de controlar la propagación y los brotes de la enfermedad. Aunque los potros son el principal animal utilizado para la evaluación de vacunas contra la gripe equina, en el presente trabajo se eligieron cobayos como modelo alternativo, ya que tienen un título insignificante de anticuerpos contra el virus de la gripe equina y son más baratos y fáciles de manejar que los potros. Se evaluaron cinco lotes de vacunas contra la gripe equina en dos modelos animales, potros y cobayos, mediante la inyección de dos dosis/animal con 4 semanas de intervalo utilizando 2 mL/animal/dosis y la evaluación de las respuestas inmunitarias mediante la prueba de inhibición de la hemaglutinación y el ensayo inmunoenzimático. En la 7ª semana posvacunación, los títulos de anticuerpos contra la gripe equina alcanzaron valores máximos de 9-10,2 y 8,7-10 unidades de inhibición de la hemaglutinación para potros y cobayos, respectivamente; las relaciones muestras/negativos fueron de 0,126-0,464 y 0,128-0,445 para ambos animales, respectivamente. Podría recomendarse el uso de cobayos como modelo animal para la evaluación de vacunas contra la gripe equina, en lugar de potros(AU)
Assuntos
AnimaisRESUMO
Equine influenza is a highly contagious disease caused by the H3N8 equine influenza virus (EIV), which is endemically distributed throughout the world. It infects equids, and interspecies transmission to dogs has been reported. The H3N8 Florida lineage, which is divided into clades 1 and 2, is the most representative lineage in the Americas. The EIV infects the respiratory system, affecting the ciliated epithelial cells and preventing the elimination of foreign bodies and substances. Certain factors related to the disease, such as an outdated vaccination plan, age, training, and close contact with other animals, favor the presentation of equine influenza. This review focuses on the molecular, pathophysiological, and epidemiological characteristics of EIV in the Americas to present updated information to achieve prevention and control of the virus. We also discuss the need for monitoring the disease, the use of vaccines, and the appropriate application of those biologicals, among other biosecurity measures that are important for the control of the virus.
RESUMO
Equine influenza virus (EIV) is one of the most important respiratory pathogens of horses as outbreaks of the disease lead to significant economic losses worldwide. In this review, we summarize the information available on equine influenza (EI) in South America. In the region, the major events of EI occurred almost in the same period in the different countries, and the EIV isolated showed high genetic identity at the hemagglutinin gene level. It is highly likely that the continuous movement of horses, some of them subclinically infected, among South American countries, facilitated the spread of the virus. Although EI vaccination is mandatory for mobile or congregates equine populations in the region, EI outbreaks continuously threaten the equine industry. Vaccine breakdown could be related to the fact that many of the commercial vaccines available in the region contain out-of-date EIV strains, and some of them even lack reliable information about immunogenicity and efficacy. This review highlights the importance of disease surveillance and reinforces the need to harmonize quarantine and biosecurity protocols, and encourage vaccine manufacturer companies to carry out quality control procedures and update the EIV strains in their products.
Assuntos
Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/virologia , Vírus da Influenza A , Infecções por Orthomyxoviridae/veterinária , Animais , Surtos de Doenças , Geografia Médica , Cavalos , Vírus da Influenza A/classificação , Vírus da Influenza A/genética , Filogenia , Vigilância em Saúde Pública , RNA Viral , Infecções Respiratórias/epidemiologia , Infecções Respiratórias/virologia , América do Sul/epidemiologiaRESUMO
Equine influenza (EI) virus is one of the most economically important pathogens of respiratory diseases of horses worldwide. Despite availability of vaccines for control of EI, the highly contagious nature and variability properties of the virus mean global outbreaks occur. Thus, continuous surveillance programs, including seroprevalence studies of disease in different countries, may contribute to better control of the disease. In this study, the seroprevalence of equine influenza in 850 horses from Brazil was investigated. The serodiagnosis was based on the single radial hemolysis (SRH) assay using influenza A/equine/Richmond/1/2007 (H3N8) antigen. Antibodies against A/equine/Richmond/1/07 (H3N8) were detected in 44.7% (380/850, 95% CI: 41.4-48.1%) of horses. Seroprevalence was significantly lower (p = 0.001) in younger animals (< 5 years, 38.6%) than in "adult" animals (5-14 years, 52.1%). There was also a significant relationship between the year of sampling and seroprevalence (p < 0.0005). The mean SRH antibody value was 42.0 mm2 (range 4-238.9 mm2), with the majority of horses (95.3%) having an SRH value ≤ 150 mm2, which is considered an insufficient level for protection of equine hosts against influenza infections and potential virus shedding. These findings indicate the need to reinforce preventive/control measures against equine influenza in Brazil.
Assuntos
Anticorpos Antivirais/sangue , Surtos de Doenças/veterinária , Doenças dos Cavalos/epidemiologia , Vírus da Influenza A Subtipo H3N8/imunologia , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/imunologia , Infecções por Orthomyxoviridae/veterinária , Animais , Brasil , Feminino , Doenças dos Cavalos/virologia , Cavalos/imunologia , Cavalos/virologia , Masculino , Infecções por Orthomyxoviridae/prevenção & controle , Estudos Retrospectivos , Fatores de Risco , Estudos Soroepidemiológicos , Eliminação de Partículas ViraisRESUMO
BACKGROUND: 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. OBJECTIVES: 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. STUDY DESIGN: Observational, descriptive study. METHODS: Virus was detected in nasopharyngeal swabs using real-time reverse transcriptase PCR (RT-PCR). Nucleotide and deduced amino acid sequences of the haemagglutinin (HA) and neuraminidase (NA) genes were obtained from EIV positive nasopharyngeal swabs, and phylogenetic analysis was undertaken. Amino acid sequences were compared against the current World Organisation for Animal Health (OIE)-recommended Florida clade 1 vaccine strain and strain components of vaccines used in Argentina. Serum samples were tested using haemagglutination inhibition test. RESULTS: Equine influenza virus infection was confirmed using real-time RT-PCR and serological testing. The phylogenetic analysis of the HA and NA genes revealed that all the EIV identified during the outbreak belong to the H3N8 subtype, Florida clade 1. Multiple amino acid changes, some of them at antigenic sites, were observed in the circulating virus when compared with the strains included in the most commonly used vaccine in Argentina. Seventy-six percent of the affected horses had been vaccinated with this vaccine, suggesting the occurrence of vaccine breakdown. MAIN LIMITATIONS: The study does not include antigenic characterisation and full genome sequencing of Argentinian strains, that could provide additional information. CONCLUSIONS: The occurrence of this multifocal equine influenza outbreak in regularly vaccinated horses is a field evidence of vaccine breakdown, reinforcing the necessity of keeping vaccine strains updated according to OIE recommendations. It also underlines the importance of the implementation of appropriate quarantine measures and restriction of horse movement in the face of disease.
Assuntos
Doenças dos Cavalos , Vírus da Influenza A Subtipo H3N8 , Infecções por Orthomyxoviridae , Animais , Argentina , Surtos de Doenças , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/virologia , Cavalos , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/veterinária , FilogeniaRESUMO
Abstract Equine influenza is one of the major respiratory infectious diseases in horses. An equine influenza virus outbreak was identified in vaccinated and unvaccinated horses in a veterinary school hospital in São Paulo, SP, Brazil, in September 2015. The twelve equine influenza viruses isolated belonged to Florida Clade 1. The hemagglutinin and neuraminidase amino acid sequences were compared with the recent isolates from North and South America and the World Organisation for Animal Health recommended Florida Clade 1 vaccine strain. The hemagglutinin amino acid sequences had nine substitutions, compared with the vaccine strain. Two of them were in antigenic site A (A138S and G142R), one in antigenic site E (R62K) and another not in antigenic site (K304E). The four substitutions changed the hydrophobicity of hemagglutinin. Three distinct genetic variants were identified during the outbreak. Eleven variants were found in four quasispecies, which suggests the equine influenza virus evolved during the outbreak. The use of an out of date vaccine strain or updated vaccines without the production of protective antibody titers might be the major contributing factors on virus dissemination during this outbreak.
Assuntos
Animais , Variação Genética , Surtos de Doenças , Infecções por Orthomyxoviridae/veterinária , Evolução Molecular , Vírus da Influenza A Subtipo H3N8/isolamento & purificação , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/virologia , Orthomyxoviridae , Proteínas Virais/genética , Brasil/epidemiologia , Análise de Sequência de DNA , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/virologia , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Substituição de Aminoácidos , Vírus da Influenza A Subtipo H3N8/classificação , Vírus da Influenza A Subtipo H3N8/genética , Genótipo , Cavalos , Hospitais Veterinários , Neuraminidase/genéticaRESUMO
Equine influenza is one of the major respiratory infectious diseases in horses. An equine influenza virus outbreak was identified in vaccinated and unvaccinated horses in a veterinary school hospital in São Paulo, SP, Brazil, in September 2015. The twelve equine influenza viruses isolated belonged to Florida Clade 1. The hemagglutinin and neuraminidase amino acid sequences were compared with the recent isolates from North and South America and the World Organisation for Animal Health recommended Florida Clade 1 vaccine strain. The hemagglutinin amino acid sequences had nine substitutions, compared with the vaccine strain. Two of them were in antigenic site A (A138S and G142R), one in antigenic site E (R62K) and another not in antigenic site (K304E). The four substitutions changed the hydrophobicity of hemagglutinin. Three distinct genetic variants were identified during the outbreak. Eleven variants were found in four quasispecies, which suggests the equine influenza virus evolved during the outbreak. The use of an out of date vaccine strain or updated vaccines without the production of protective antibody titers might be the major contributing factors on virus dissemination during this outbreak.(AU)
Assuntos
Animais , Cavalos/virologia , Vírus da Influenza A Subtipo H3N8 , Infecções por Orthomyxoviridae/epidemiologia , Variação Genética , Brasil , Neuraminidase , HemaglutininasRESUMO
Equine influenza is one of the major respiratory infectious diseases in horses. An equine influenza virus outbreak was identified in vaccinated and unvaccinated horses in a veterinary school hospital in São Paulo, SP, Brazil, in September 2015. The twelve equine influenza viruses isolated belonged to Florida Clade 1. The hemagglutinin and neuraminidase amino acid sequences were compared with the recent isolates from North and South America and the World Organisation for Animal Health recommended Florida Clade 1 vaccine strain. The hemagglutinin amino acid sequences had nine substitutions, compared with the vaccine strain. Two of them were in antigenic site A (A138S and G142R), one in antigenic site E (R62K) and another not in antigenic site (K304E). The four substitutions changed the hydrophobicity of hemagglutinin. Three distinct genetic variants were identified during the outbreak. Eleven variants were found in four quasispecies, which suggests the equine influenza virus evolved during the outbreak. The use of an out of date vaccine strain or updated vaccines without the production of protective antibody titers might be the major contributing factors on virus dissemination during this outbreak.
Assuntos
Surtos de Doenças , Evolução Molecular , Variação Genética , Doenças dos Cavalos/epidemiologia , Doenças dos Cavalos/virologia , Vírus da Influenza A Subtipo H3N8/isolamento & purificação , Infecções por Orthomyxoviridae/veterinária , Substituição de Aminoácidos , Animais , Brasil/epidemiologia , Genótipo , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Cavalos , Hospitais Veterinários , Vírus da Influenza A Subtipo H3N8/classificação , Vírus da Influenza A Subtipo H3N8/genética , Neuraminidase/genética , Orthomyxoviridae , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/virologia , Análise de Sequência de DNA , Proteínas Virais/genéticaRESUMO
Abstract Equine influenza is one of the major respiratory infectious diseases in horses. An equine influenza virus outbreak was identified in vaccinated and unvaccinated horses in a veterinary school hospital in São Paulo, SP, Brazil, in September 2015. The twelve equine influenza viruses isolated belonged to Florida Clade 1. The hemagglutinin and neuraminidase amino acid sequences were compared with the recent isolates from North and South America and the World Organisation for Animal Health recommended Florida Clade 1 vaccine strain. The hemagglutinin amino acid sequences had nine substitutions, compared with the vaccine strain. Two of them were in antigenic site A (A138S and G142R), one in antigenic site E (R62K) and another not in antigenic site (K304E). The four substitutions changed the hydrophobicity of hemagglutinin. Three distinct genetic variants were identified during the outbreak. Eleven variants were found in four quasispecies, which suggests the equine influenza virus evolved during the outbreak. The use of an out of date vaccine strain or updated vaccines without the production of protective antibody titers might be the major contributing factors on virus dissemination during this outbreak.
RESUMO
The Influenza virus type A, subtype H3N8, is the etiological agent of the Equine Influenza, responsible for several epidemics and endemic respiratory diseases in world level, besides in the Rio de Janeiro State, Brazil. The objective of this work was to evaluate the role of errant equids, as infectious sources of the Influenza virus, subtype H3N8. The survey was performed from the research of specific antibodies for this virus in 1106 sera analyzed by the inhibition of the hemagglutination test. The high percentile (35,9%) of seropositive animals found in this study evidenced its importance as infectious sources of the Influenza virus, subtype H3N8, to the national equine flock.
O vírus Influenza A, subtipo H3N8, é o agente etiológico da Influenza Eqüina, responsável por diversas epidemias e endemias respiratórias em nível mundial, inclusive no Estado do Rio de Janeiro, Brasil. O objetivo deste trabalho foi avaliar a importância de eqüídeos errantes, como fontes de infecção do vírus Influenza, subtipo H3N8. A enquete foi realizada a partir da pesquisa de anticorpos específicos para este vírus em 1106 soros analisados através da prova de inibição da hemaglutinação. O elevado percentual (35,9%) de animais soropositivos encontrados evidencia seu papel como uma importante fonte de infecção deste vírus para o rebanho eqüino nacional.
RESUMO
The Influenza virus type A, subtype H3N8, is the etiological agent of the Equine Influenza, responsible for several epidemics and endemic respiratory diseases in world level, besides in the Rio de Janeiro State, Brazil. The objective of this work was to evaluate the role of errant equids, as infectious sources of the Influenza virus, subtype H3N8. The survey was performed from the research of specific antibodies for this virus in 1106 sera analyzed by the inhibition of the hemagglutination test. The high percentile (35,9%) of seropositive animals found in this study evidenced its importance as infectious sources of the Influenza virus, subtype H3N8, to the national equine flock.
O vírus Influenza A, subtipo H3N8, é o agente etiológico da Influenza Eqüina, responsável por diversas epidemias e endemias respiratórias em nível mundial, inclusive no Estado do Rio de Janeiro, Brasil. O objetivo deste trabalho foi avaliar a importância de eqüídeos errantes, como fontes de infecção do vírus Influenza, subtipo H3N8. A enquete foi realizada a partir da pesquisa de anticorpos específicos para este vírus em 1106 soros analisados através da prova de inibição da hemaglutinação. O elevado percentual (35,9%) de animais soropositivos encontrados evidencia seu papel como uma importante fonte de infecção deste vírus para o rebanho eqüino nacional.