Nishi Tatsuya, Yamada Manabu, Fukai Katsuhiko, Shimada Nobuaki, Morioka Kazuki, Yoshida Kazuo, Sakamoto Kenichi, Kanno Toru, Yamakawa Makoto
Exotic Disease Research Unit, Division of Transboundary Animal Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1, Josui-honcho, Kodaira, Tokyo, 187-0022, Japan.
Exotic Disease Research Unit, Division of Transboundary Animal Diseases, National Institute of Animal Health, National Agriculture and Food Research Organization, 6-20-1, Josui-honcho, Kodaira, Tokyo, 187-0022, Japan.
Vet Microbiol. 2017 Feb;199:62-67. doi: 10.1016/j.vetmic.2016.12.025. Epub 2016 Dec 21.
Foot-and-mouth disease virus (FMDV) is highly contagious and has a high mutation rate, leading to extensive genetic variation. To investigate how FMDV genetically evolves over a short period of an epidemic after initial introduction into an FMD-free area, whole L-fragment sequences of 104 FMDVs isolated from the 2010 epidemic in Japan, which continued for less than three months were determined and phylogenetically and comparatively analyzed. Phylogenetic analysis of whole L-fragment sequences showed that these isolates were classified into a single group, indicating that FMDV was introduced into Japan in the epidemic via a single introduction. Nucleotide sequences of 104 virus isolates showed more than 99.56% pairwise identity rates without any genetic deletion or insertion, although no sequences were completely identical with each other. These results indicate that genetic substitutions of FMDV occurred gradually and constantly during the epidemic and generation of an extensive mutant virus could have been prevented by rapid eradication strategy. From comparative analysis of variability of each FMDV protein coding region, VP4 and 2C regions showed the highest average identity rates and invariant rates, and were confirmed as highly conserved. In contrast, the protein coding regions VP2 and VP1 were confirmed to be highly variable regions with the lowest average identity rates and invariant rates, respectively. Our data demonstrate the importance of rapid eradication strategy in an FMD epidemic and provide valuable information on the genome variability of FMDV during the short period of an epidemic.
口蹄疫病毒（FMDV）具有高度传染性且突变率高，导致广泛的基因变异。为了研究FMDV在初次引入无口蹄疫地区后的短时间内如何在疫情中发生基因进化，我们测定了从日本2010年持续不到三个月的疫情中分离出的104株FMDV的完整L片段序列，并进行了系统发育和比较分析。对完整L片段序列的系统发育分析表明，这些分离株被归类为一个单一的组，这表明在疫情中FMDV是通过单次引入进入日本的。104株病毒分离株的核苷酸序列显示，两两之间的同一性率超过99.56%，没有任何基因缺失或插入，尽管没有序列彼此完全相同。这些结果表明，FMDV的基因替代在疫情期间逐渐且持续发生，并且通过快速根除策略可以防止产生广泛的突变病毒。通过对每个FMDV蛋白编码区变异性的比较分析，VP4和2C区域显示出最高的平均同一性率和不变率，并被确认为高度保守。相比之下，蛋白编码区VP2和VP1分别被确认为高度可变区域，其平均同一性率和不变率最低。我们的数据证明了在口蹄疫疫情中快速根除策略的重要性，并提供了关于疫情短时间内FMDV基因组变异性的有价值信息。
