Further Isolation of a Recombinant Virus (H1N2, Formerly Hsw1N2) from a Pig in Japan in 1980

Abstract

In September 1980, an outbreak of febrile respiratory disease was observed in a herd of sows (1‐2 years of age) in Ehime Prefecture, Japan. Most of the swine showed clinical signs of disease such as depression, anorexia, fever, nasal discharge, and cough. A hemagglutinating agent was isolated from a nasal swab from one of the diseased pigs. By cross‐hemagglutination‐inhibition and neuraminidase‐inhibition tests with antisera to influenza viruses of swine origin, the isolate was identified as an influenza A virus of the H1N2 (former designation, Hsw1N2) subtype, and designated A/swine/Ehime/1/80 (H1N2). Significant antibody rises against the surface antigens of the isolate were found in convalescent swine sera. The distribution of antibody against H1N2 virus in swine sera in Ehime Prefecture was examined. Seven (8%) of 93 sera collected after the outbreak (in 1981) showed antibodies to only H1 and N2 antigens but none of the sera before the outbreak contained such antibodies, indicating that H1N2 virus had been restrictedly prevalent among swine but was not wide‐spread until 1981.

Characterization of a 1980-swine recombinant influenza virus possessing H1 hemagglutinin and N2 neuraminidase similar to that of the earliest Hong Kong (H3N2) virus

“…In 1980 some (tt.Y.) of us also isolated another recombinant virus possessing Hi (swi) hemagglutinin and N2 neuraminidasc from a pig in Ehime prefecture, Japan (38).…”

Occurrence of a Pig Respiratory Disease Associated with Swine Influenza A (H1N2) Virus in Tochigi Prefecture, Japan

“…The reassortant H1N2 virus was first isolated in Japan from pigs in Kanagawa Prefecture, the central part of Japan, in 1978 [26]. Subsequently, isolations of the SIVs from pigs or occurrences of SI were reported in many regions of Japan with the H1N2 subtype being predominant [6,10,19,[23][24][25][26]29]. Although genetic analysis of the H1N2 SIVs isolated in Japan has been reported, the clinical features of SI and the economic losses caused by it have not been described in detail.…”

Genetic Characterization of H1N2 Influenza A Viruses Isolated from Pigs throughout the United States

“…However, H1N2 viruses were isolated previously from pigs in France in 1987 and 1988 (4), in Japan in 1978 to 1980 and 1989 to 1992 (6, 9, 10, 12, 13, 16), and in the United Kingdom in 1994 and thereafter (1,2). The viruses from Japan and France were shown to be products of reassortment between classical (Japan) or avian-like (France) swine H1N1 viruses and human-lineage H3N2 viruses (4,6,9,10,12,13,16). In contrast, the H1N2 viruses in the United Kingdom resulted from multiple reassortment events.…”