| Abstract: | During the epidemic of equine influenza which occurred in India in 1987, serum samples were collected at late acute/early convalescent phase (7–9 days), at 5 weeks and at 18–23 weeks after onset of illness, from six affected horses from the Union Territory of Changigarh, and Nawanshahr, Punjab State, India, and were examined for antibodies to A/eq-1 and A/eq-2 influenza viruses by hemagglutination inhibition (HI) tests. It was found that the antibody response to A/eq-1 virus strains, Ludhiana/87 and Prague/56, was stronger and antibodies persisted at high levels in four animals. The fifth animal showed a diagnostic decrease in HI titers while the sixth animal seroconverted. The corresponding HI titers to A/eq-2/Ludhiana virus showed a 4-fold decrease in all six animals.Another nine equine animals in the single convalescent serum samples had detectable or high HI titers against A/eq-1 and A/eq-2 viruses.In serum samples from horses and ponies, taken 5 weeks to 9 months after onset of illness, little or no difference in antibody titers to A/eq-2/Miami/63 and A/eq-2/Fontainebleau/79 strains was found.It seems clear that the antibody titers that ensued were indicative of recent influenza infections. Apparently, two distinct equine influenza viruses, A/eq-1 and A/eq-2, were involved during the epidemic, infecting the equine animals simultaneously in the region. |
