title: Molecular epidemiological and serological studies of bovine leukemia virus (BLV) infection in Thailand cattle.
abstract: BLV is the etiological agent of enzootic bovine leucosis. BLV has negative effects on animal health and causes economic losses worldwide. However, epidemiological studies on BLV are relatively unknown in many parts of Asian countries. Thus, this study sought to explore BLV infections in cattle in Thailand to determine the extent of the geographic distribution of BLV and to measure its prevalence rates. For this study, 744 cattle from 11 farms in 9 provinces of Thailand were screened in 2013 and 2014 by ELISA and nested PCR. Of those cattle, 41 BLVs were genetically characterized using 188 BLV gp51 env gene sequences available in GenBank. The BLV prevalence in Thailand was high, ranging from 5.3% to 87.8%, as determined by PCR and 11.0% to 100% as determined by ELISA, according to geographical region. Phylogenetic analysis showed that Thailand BLVs belonged to genotypes 1 and 6 and a new genotype 10, which are sporadically observed across Thailand with a prevalence of 31.7%, 19.5%, and 48.8%, respectively. A significant number of amino acid substitutions were also found in the gp51 sequences, of which unique changes in genotype 10 have not been reported previously. Briefly, the majority of substitutions were confined to CD4+/CD8+ T-cell epitopes, neutralizing domains, and E-D-A epitopes. Those observations indicate that BLV infections in Thailand cattle are prevalent and that the geographic distribution of BLV is dynamic, with a high level of genetic diversity. This distribution implies a long-term BLV infection in cattle populations and the movement of infected cattle. In sum, this study suggests that intensive surveillance and effective prevention strategies are required to determine the prevalence of BLV in Thailand and control continuous infections with BLVs.
authors.affiliation: Viral Disease Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: sys305@korea.kr.
authors.forename: EunJung
authors.initials: E
authors.lastname: Lee
authors.affiliation: Viral Disease Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: happylion00@korea.kr.
authors.forename: Eun-Ju
authors.initials: EJ
authors.lastname: Kim
authors.affiliation: National Institute of Animal Health, Bangkok 10900, Thailand. Electronic address: jrattha@gmail.com.
authors.forename: Jadsada
authors.initials: J
authors.lastname: Ratthanophart
authors.affiliation: National Institute of Animal Health, Bangkok 10900, Thailand. Electronic address: vrashaneekorn@gmail.com.
authors.forename: Ratchaneekorn
authors.initials: R
authors.lastname: Vitoonpong
authors.affiliation: Viral Disease Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: lordpraiser@korea.kr.
authors.forename: Bo-Hye
authors.initials: BH
authors.lastname: Kim
authors.affiliation: Viral Disease Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: chois38@korea.kr.
authors.forename: In-Soo
authors.initials: IS
authors.lastname: Cho
authors.affiliation: Veterinary Drugs and Biologics Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: songjysong@korea.kr.
authors.forename: Jae-Young
authors.initials: JY
authors.lastname: Song
authors.affiliation: Animal Disease Diagnostic Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: naturelkk@korea.kr.
authors.forename: Kyoung-Ki
authors.initials: KK
authors.lastname: Lee
authors.affiliation: Viral Disease Division, Animal and Plant Quarantine Agency, Anyang 430-757, Gyeonggido, Republic of Korea. Electronic address: shinyk2009@korea.kr.
authors.forename: Yeun-Kyung
authors.initials: YK
authors.lastname: Shin
mesh_terms: D019943:Amino Acid Substitution; D000822:Animal Husbandry; D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology / Q000821:virology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology / Q000473:pathology / Q000821:virology; D002417:Cattle; D016583:Enzootic Bovine Leukosis / Q000453:epidemiology* / Q000276:immunology / Q000473:pathology / Q000821:virology; D018984:Epitopes, T-Lymphocyte / Q000235:genetics* / Q000276:immunology; D015870:Gene Expression; D014644:Genetic Variation; D005838:Genotype; D054884:Host-Pathogen Interactions; D001909:Leukemia Virus, Bovine / Q000145:classification / Q000235:genetics* / Q000254:growth & development; D017720:Molecular Epidemiology; D009154:Mutation; D010802:Phylogeny; D015995:Prevalence; D013785:Thailand / Q000453:epidemiology; D014759:Viral Envelope Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: D018984:Epitopes, T-Lymphocyte; D014759:Viral Envelope Proteins
keywords: Bovine leukemia virus (BLV); Molecular epidemiology; Serology; Thailand