Evolution of equine influenza viruses (H3N8) during a Brazilian outbreak, 2015

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 The use of an out of date vaccine strain or updated vaccines without the production of protective antibody titers might be the major contributing factors on virus dissemination during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.

Relevamiento serológico de anticuerpos contra enfermedades virales de interés sanitario en llamas (Lama glama) de la provincia de Jujuy, Argentina / Serological survey of antibodies aainst vital diseases of public health interest in llamas (Lama glama) from Jujuy rpovince, Argentina

Las poblaciones de llamas de Argentina se concentran principalmente en la provincia de Jujuy; su explotación representa un importante recurso económico de las comunidades altoandinas. El objetivo de este trabajo fue evaluar la seroprevalencia de anticuerpos contra algunos agentes virales asociados a enfermedades de impacto productivo en rodeos de llamas de Jujuy. Se analizaron 349 sueros de llamas adultas de 6 departamentos de la puna jujeña ubicados por encima de los 3300 msnm. Se obtuvo una prevalencia del 100 % para rotavirus grupo A y del 70 % para el virus parainfluenza-3 bovino, mientras que no se detectaron reactores para herpesvirus bovino 1, virus de la diarrea viral bovina, influenza A humana (H1N1) e influenza equina (H3N8). Los resultados obtenidos confirman la amplia distribución de rotavirus y virus parainfluenza y la baja susceptibilidad a herpesvirus y pestivirus en las tropas de llamas de la puna jujeña

Llama population from Argentina is mainly concentrated in the Andean Puna, Jujuy. Llamas represent an important economic resource for the Andean communities. The aim of this study was to investigate the prevalence of antibodies against viral antigens associated to viral diseases of economic impact (neonatal diarrhea, reproductive and respiratory syndromes). A total of 349 serum samples from adult llamas were analyzed. The obtained antibody prevalence was 100 % for Rotavirus A and 70 % for Bovine parainfluenza virus 3. In contrast, no reactors were detected to Bovine herpesvirus 1, Bovine viral diarrhea virus 1, Human influenza A virus (H1N1) and Equine influenza virus (H3N8). These results confirm the wide circulation of rotavirus and parainfluenza virus in Argentinean llamas and suggest that susceptibility to infection with bovine herpesvirus, pestivirus and influenza A viruses is low. This serologic survey provides novel information regarding the epidemiology of viral diseases affecting llamas from the Argentinean Andean Puna

Evaluation of infectivity of a canine lineage H3N8 influenza A virus in ponies and in primary equine respiratory epithelial cells.

OBJECTIVE: To evaluate whether an equine-derived canine H3N8 influenza A virus was capable of infecting and transmitting disease to ponies. ANIMALS: 20 influenza virus-seronegative 12- to 24-month-old ponies. PROCEDURES: 5 ponies were inoculated via aerosol exposure with 10(7) TCID(50) of A/Canine/Wyoming/86033/07 virus (Ca/WY)/pony. A second group of 5 ponies (positive control group) was inoculated via aerosol exposure with a contemporary A/Eq/Colorado/10/07 virus (Eq/CO), and 4 sham-inoculated ponies served as a negative control group. To evaluate the potential for virus transmission, ponies (3/inoculation group) were introduced 2 days after aerosol exposure and housed with Ca/WY- and Eq/CO-inoculated ponies to serve as sentinel animals. Clinical signs, nasal virus shedding, and serologic responses to inoculation were monitored in all ponies for up to 21 days after viral inoculation. Growth and infection characteristics of viruses were examined by use of Madin-Darby canine kidney cells and primary equine and canine respiratory epithelial cells. RESULTS: Ponies inoculated with Ca/WY had mild changes in clinical appearance, compared with results for Eq/CO-inoculated ponies. Additionally, Ca/WY inoculation induced significantly lower numbers for copies of the matrix gene in nasal secretions and lower systemic antibody responses in ponies than did Eq/CO inoculation. The Ca/WY isolate was not transmitted to sentinel ponies. CONCLUSIONS AND CLINICAL RELEVANCE: Inoculation of ponies with the canine H3N8 isolate resulted in mild clinical disease, minimal nasal virus shedding, and weak systemic antibody responses, compared with responses after inoculation with the equine H3N8 influenza isolate. These results suggested that Ca/WY has not maintained infectivity for ponies.

Infectivity of equine H3N8 influenza virus in bovine cells and calves.

BACKGROUND: Serological evidence for influenza A, subtype H1 and H3 virus infections of bovines, associated with respiratory disease and decreased milk production, has been reported. Equine H3N8 influenza virus circulates widely and was responsible for the introduction of H3N8 influenza into canines. OBJECTIVE: To explore the possibility that equine H3N8 influenza might also infect bovines. METHODS: To assess the incidence of seroconversion in the field, a retrospective survey of bovine serum samples was carried out. Also, primary cultures of bovine nasal turbinate cells, and live beef calves, were studied for their permissiveness to infection. RESULTS AND CONCLUSIONS: We found serological evidence of exposure of bovines in Kentucky to H3 influenza. We demonstrate that cultured bovine respiratory epithelium is permissive for the growth of equine H3N8 influenza virus in vitro, but this virus does not replicate extensively or produce disease in experimentally inoculated cattle.

The pathology of bronchointerstitial pneumonia in young foals associated with the first outbreak of equine influenza in Australia.

REASONS FOR PERFORMING STUDY: The first outbreak of equine influenza virus (EIV) infection was confirmed in Australia in 2007. Some EIV-positive young foals died with bronchointerstitial pneumonia, an rare disease process in this age group that is often postulated to be caused by viral infection. OBJECTIVES: The aim of this study was to describe post mortem lesions in EIV-infected foals. METHODS: Post mortem examinations were conducted on 11 young foals (age 2-12 days) submitted to the Scone Veterinary Hospital, NSW over a 2-month period in 2007. The foals had presented with or developed fatal pneumonia, and were known or suspected to be EIV-positive. Equine influenza virus nucleic acid was detected in tissue specimens using an Influenza A group reactive real-time reverse transcriptase PCR assay. RESULTS: Grossly there was diffuse or extensive pulmonary consolidation. Histological changes included: bronchiolar and alveolar necrosis; neutrophilic infiltration; hyaline membrane formation; and hyperplasia and squamous metaplasia of airway epithelium. Tissues for 10 foals were EIV-positive, with a positive nasal swab from the remaining animal. CONCLUSIONS: This is the first detailed pathological description of bronchointerstitial pneumonia associated with EIV infection in young foals. It is also the first series of such cases in which a causative agent has consistently been detected. POTENTIAL RELEVANCE: Given the findings in this outbreak, and a previous outbreak in the UK in 1965 involving a similarly naive population, veterinary clinicians and pathologists should be aware that EIV can cause fatal bronchointerstitial pneumonia in young foals that do not have maternal immunity. The lesions did not differ from those previously reported in foals of various ages with bronchointerstitial pneumonia of other or undefined causes, indicating that this is most likely a stereotypical response to a variety of insults. Therefore, tissue specimens should be obtained from cases of pneumonia in young foals for virological and bacteriological testing.