Equine influenza outbreak in India (2008–09): Virus isolation, sero-epidemiology and phylogenetic analysis of HA gene

Genetic Analysis of the Neuraminidase (NA) Gene of Equine Influenza Virus (H3N8) from Epizootic of 2008–2009 in India

“…The phylogenetic analysis of NA gene showed the clustering of Indian isolates with those of Kazakhstan, Mongolian, Chinese, and Japanese isolates. These broadly grouped in Florida clade 2 and followed lineage pattern of EIVs as that of HA genes of our earlier studies [29]. However, in the present study, we could also find that a new subgroup of Asian isolates showing robustness in phylogeny as supported by high bootstrap value (100) emerged from Kazakhstan/07 isolate and all the viruses isolated subsequently from Asia in chronology belonged to this group.…”

“…In recent times (2007 onwards), Florida clade 1 viruses have been implicated in outbreaks in Australia [www.equineinfluenzainquiry.gov.au] and Japan [34] while clade 2 viruses have been responsible for the outbreaks in Asian countries including Kazakhstan (2007-08), Mongolia (2007), China , India (2008-09) [17,29] and Europe (2006-07) [3]. EI infection re-emerged in India in 2008 after a gap of 20 years since the first outbreak in 1987 [26] and affected equine population in 13 states of the country [28][29][30].…”

“…Therefore, continuous characterization of various genes of all influenza virus isolates especially those expressing the surface glycoproteins is of strategic importance, as it gives an insight into the accumulation of point mutations which can be of significance and have bearing on the virus getting selective advantage to evade immune system. Further, the phylogenetic analysis of the matrix gene of EIVs (H3N8) from epizootic in India in 2008-09 clustered the isolates in a separate Asian Clade along with other isolates from Asia (Mongolia and China) during this period, although HA gene analysis had placed them along with the EIVs of Florida clade 2 [29]. Thus the concern is to analyze and compare the nucleotide and protein sequences of other genes from Indian isolates for their mutational changes and evolutionary relationship with other EIVs isolated across the globe.…”

Epidemiological and virological findings during multiple outbreaks of equine influenza in South America in 2012

“…Florida clade 1 viruses are endemic in the USA but have also caused outbreaks in South Africa,13 Japan,14 Australia 15 and Europe 11, 16, 17, 18, 19. Florida clade 2 viruses have predominated in Europe but have also been the cause of major outbreaks of EI in China,20 Mongolia 21 and India 22…”

Antibody Responses Induced by Japanese Whole inactivated Vaccines against Equine Influenza Virus (H3N8) Belonging to Florida Sublineage Clade2

“…A/equine/South Africa/4/03 (South Africa03) was classified as a Florida sublineage Clade (Fc)1 [3,14], which has diverged from the American lineage since around 1996 [10,11]. In 2010, OIE recommended the inclusion of an Fc2 strain of equine influenza virus (H3N8), which is represented by A/equine/Richmond/1/07 (Richmond07) [15], in equine influenza vaccines because Fc2 viruses have been widely circulating in the United Kingdom and Eurasia [1,4,6,18,20], and the antigenic characteristics of Fc1 and clade2 are distinguishable. Fc2 appears to have diverged from Fc1 since the first introduction of the latter into the United Kingdom in 2003 [12].…”