Identification of equine influenza virus infection in Asian wild horses (Equus przewalskii).

The research article is about a study on an outbreak of equine influenza in the Asian wild horse population in China in 2007 where the authors identified and analyzed the specific strain of virus that caused the epidemic.

Study Background and Data Collection

• An outbreak of equine influenza, a common highly infectious disease of horses, occurred among the Asian wild horse population in Xinjiang Province, China in 2007.
• The scientists collected nasal swabs from the infected horses as samples and inoculated them into specific fertilised chicken eggs used for virus growth.

Analysis and Findings

• The complete genome of the virus sample was sequenced and analyzed. The amino acid sequence comparison revealed that the isolated virus was an equine influenza virus strain, named A/equine/Xinjiang/4/2007 by the researchers.
• The gene sequence of the virus showed more than 99% similarity to equine influenza strains belonging to the Florida-2 sublineage, a particular subtype of the virus which was circulating in China at the same time.
• It had less similarity with the strain A/equine/Qinghai/1/1994, which belongs to a European lineage and had been isolated during the last notable outbreak in China. This comparison was also confirmed by a phylogenetic analysis, an examination of the evolutionary relationships between different strains.

Neuraminidase Segment and Potential Source of the Virus

• Researchers further noted that the deduced amino acid sequence of neuraminidase, an enzyme on the surface of influenza viruses, of the A/equine/Xinjiang/4/2007 strain was identical to that of A/equine/California/8560/2002, a strain found in the USA.
• This sequence was also found to be similar to those of Florida-2 sublineage strains identified in other countries, as well as nine other field strains isolated in China between 2007 and 2008.
• This led the researchers to suggest that the neuraminidase segment of A/equine/Xinjiang/4/2007 may have originated from the equine influenza virus strains from foreign countries.

Significance of the Study

• This study represents the first recorded outbreak of equine influenza in the Asian wild horse population.
• The complete genome of the identified equine influenza virus which caused the epidemic is provided and analyzed in this research.
• Such studies are crucial in understanding the origins and evolution of influenza viruses, which in turn, aids in disease control and the development of effective vaccines.