Isolation and characterisation of an H3N8 equine influenza virus in Australia, 2007.

The research paper discusses the isolation and characterization of the H3N8 equine influenza virus in Australia in 2007. Before the specified year, there had been no diagnosis of this nature in horses. Through sequence analysis, the researchers confirmed the virus as an H3 subtype of the American Florida lineage, known as Clade 1.

Confirmation of Equine Influenza

• The research started with the information that before 2007, the H3N8 equine influenza virus had never been diagnosed in Australia. It became apparent when horses at the Eastern Creek Animal Quarantine Station near Sydney showed symptoms.
• On 22 August 2007, infection was confirmed, after which the researchers were able to isolate the virus. This virus was subsequently named “A/equine/Sydney/2888-8/2007”.

Sequence Analysis

• The researchers conducted a sequence analysis of the haemagglutinin (HA) gene, a primary determinant of virus infection. The HA protein initiates the infection process by binding to the epithelial cells of the host respiratory tract. Therefore, analysing HA can provide insights into the virus’s properties and behaviour.
• The sequence analysis confirmed the isolated virus as an H3 subtype. This subtype was a variant belonging to the American Florida lineage, now referred to as Clade 1. Essentially, this classified the Australian virus as belonging to a strain common in North America.

Comparison with Other Viruses

• The HA sequence of the isolated Australian virus was identical to that of a virus isolated from an outbreak in Japan occurring around the same time. This indicates a possible connection or similarity in the originating source of the outbreaks in Australia and Japan.
• Moreover, the HA sequence showed high homology to the viruses circulating in North America, suggesting that the Australian strain might have originated from there or shared a common source.