Arch Virol (2004) 149: 1415–1422
Phylogenetic analysis of an H1N2 inﬂuenza A virus
isolated from a pig in Korea
K. Jung and C. Chae
Department of Veterinary Pathology, College of Veterinary Medicine
and School of Agricultural Biotechnology, Seoul National University,
Kwanak-Gu, Seoul, Republic of Korea
Received January 7, 2004; accepted February 19, 2004
Published online April 5, 2004
Summary. An inﬂuenza H1N2 virus was isolated from a pig during an severe
outbreak of respiratory disease in a Korean herd. The neuraminidase (NA) and
PB1 genes of the H1N2 isolate were of human origin, while the hemagglutinin
(HA), matrix (M), nucleoprotein (NP), and non-structural (NS) genes were of
swine origin and PA and PB2 gene were of avain origin. Phylogenetic results
indicate that the Korean H1N2 isolate was closely related to H1N2 viruses isolated
recently from pigs in the United States.
Inﬂuenza viruses are members of family Orthomyxoviridae and have segmented,
negative-sense RNA genomes. There are 15 different subtypes of hemagglutinin
(HA) and 9 different subtypes of neuraminidase (NA) that can be differentiated
both antigenically and genetically . Currently three main subtypes of inﬂuenza
virus circulate in different swine populations throughout the world: H1N1, H3N2,
and H1N2 [6–12, 15, 17, 18].
H1N2 viruses were isolated previously from pigs in United States in 1999
[6, 8], in France in 1987 and 1988 , in Japan in 1978 to 1980 and 1989 to
1992 [7, 10–12, 15, 18], and in the United Kingdom in 1994 and thereafter [1, 2].
The viruses from the United States most likely arose from the reassortment of a
classical H1 swine inﬂuenza virus with one of the recent reassortant H3N2 swine
isolates [8, 9]. 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 [6, 7, 10–12, 15, 18]. In contrast, the H1N2
viruses in the United Kingdom resulted from multiple reassortment events [1, 2].