title: Genetic diversity in the feline leukemia virus gag gene.
abstract: Feline leukemia virus (FeLV) belongs to the Gammaretrovirus genus and is horizontally transmitted among cats. FeLV is known to undergo recombination with endogenous retroviruses already present in the host during FeLV-subgroup A infection. Such recombinant FeLVs, designated FeLV-subgroup B or FeLV-subgroup D, can be generated by transduced endogenous retroviral env sequences encoding the viral envelope. These recombinant viruses have biologically distinct properties and may mediate different disease outcomes. The generation of such recombinant viruses resulted in structural diversity of the FeLV particle and genetic diversity of the virus itself. FeLV env diversity through mutation and recombination has been studied, while gag diversity and its possible effects are less well understood. In this study, we investigated recombination events in the gag genes of FeLVs isolated from naturally infected cats and reference isolates. Recombination and phylogenetic analyses indicated that the gag genes often contain endogenous FeLV sequences and were occasionally replaced by entire endogenous FeLV gag genes. Phylogenetic reconstructions of FeLV gag sequences allowed for classification into three distinct clusters, similar to those previously established for the env gene. Analysis of the recombination junctions in FeLV gag indicated that these variants have similar recombination patterns within the same genotypes, indicating that the recombinant viruses were horizontally transmitted among cats. It remains to be investigated whether the recombinant sequences affect the molecular mechanism of FeLV transmission. These findings extend our understanding of gammaretrovirus evolutionary patterns in the field.
authors.affiliation: Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
authors.forename: Maki
authors.initials: M
authors.lastname: Kawamura
authors.affiliation: Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
authors.forename: Shinya
authors.initials: S
authors.lastname: Watanabe
authors.affiliation: Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Odahara
authors.affiliation: Department of Molecular Life Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1193, Japan.
authors.forename: So
authors.initials: S
authors.lastname: Nakagawa
authors.affiliation: Laboratory of Small Animal Internal Medicine, Joint Faculty of Veterinary Medicine, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Endo
authors.affiliation: Department of Veterinary Internal Medicine, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
authors.forename: Hajime
authors.initials: H
authors.lastname: Tsujimoto
authors.affiliation: Laboratory of Molecular Immunology and Infectious Disease, The United Graduate School of Veterinary Science, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan; Laboratory of Molecular Immunology and Infectious Disease, Joint Faculty of Veterinary Medicine, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8515, Japan. Electronic address: kaz@yamaguchi-u.ac.jp.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Nishigaki
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D002415:Cats; D015752:Genes, env / Q000235:genetics*; D015750:Genes, gag / Q000235:genetics*; D014644:Genetic Variation; D005256:Leukemia Virus, Feline / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010802:Phylogeny; D011995:Recombination, Genetic; D012190:Retroviridae / Q000235:genetics* / Q000302:isolation & purification; D012192:Retroviridae Infections / Q000635:transmission / Q000662:veterinary* / Q000821:virology; D017422:Sequence Analysis, DNA
keywords: Endogenous retrovirus; Feline leukemia virus (FeLV); Gag; Genetic diversity; Recombination