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

Author(s)

Favaro, Patricia Filippsen ; Fernandes, Wilson Roberto ; Reischak, Dilmara ; Brandao, Paulo Eduardo ; de Souza Silva, Sheila Oliveira ; Richtzenhain, Leonardo Jose

• Document type: Journal article
• Source: Brazilian Journal of Microbiology; v. 49, n. 2, p. 11-pg., 2018-04-01.

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 Sao 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 (A1385 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 The use of an out of date vaccine strain or updated vaccines without the production of protective antibody titers might be the major contributing factors on virus dissemination during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. (C) 2017 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. (AU)

• FAPESP's process: 11/03234-7 - Serological and molecular characterization of equine influenza virus (EIV) in horses from the São Paulo State
• Grantee: Leonardo José Richtzenhain
• Support Opportunities: Regular Research Grants