Agbemabiese Chantal A, Nakagomi Toyoko, Suzuki Yoshiyuki, Armah George, Nakagomi Osamu
Department of Hygiene and Molecular Epidemiology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan.
Noguchi Memorial Institute for Medical Research, College of Health Sciences, University of Ghana, Accra, Ghana.
J Gen Virol. 2015 Aug;96(8):2219-2231. doi: 10.1099/vir.0.000174. Epub 2015 May 1.
Unusual human G6P[6] rotavirus A (RVA) strains have been reported sporadically in Europe and Africa, but how they evolved was not fully understood. The whole genome of a Ghanaian G6P[6] strain designated PML1965 (2012) was analysed to understand how it evolved in Africa and to learn how its G6 VP7 gene was related to that of rotaviruses of human and artiodactyl origin. The genotype constellation of RVA/Human-wt/GHA/PML1965/2012/G6P[6] was G6-P-[6]-I2-R2-C2-M2-A2-N2-T2-E2-H2. It shared sublineages with G6P[6] strains previously detected in Italy and Africa in all genome segments except the VP6 gene of a few Burkinabe and Cameroonian strains and both the VP6 and NSP4 genes of Guinea Bissau strains. The VP7 gene of the G6P[6] strains appeared to derive from those of human G6P[9] strains, and they were distantly related to the VP7 genes of artiodactyl G6 or human G6P[14] strains. The time of the most recent common ancestor of the VP7 sequences of G6P[6] strains was estimated to be the year 1998. The evolutionary rates of the VP7 genes in bovine and human G6 rotaviruses were 6.93 × 10(-4) and 3.42 × 10(-3) nucleotide substitutions site(-1) year(-1), respectively, suggesting an accelerated adaptive process in the new host. The sequences of the remaining 10 genome segments of PML1965 clustered with those of G2 and G8 human rotaviruses detected in Africa possessing the DS-1-like genetic background. In conclusion, PML1965 evolved from G2 or G8 RVA strains with DS-1-like background, acquiring the G6 VP7 gene from a human G6P[9] RVA and not from an artiodactyl G6 RVA strain.
欧洲和非洲曾零星报道过不寻常的人G6P[6]轮状病毒A（RVA）毒株，但它们的进化方式尚未完全明晰。对一株名为PML1965（2012）的加纳G6P[6]毒株的全基因组进行了分析，以了解其在非洲的进化情况，以及其G6 VP7基因与人和偶蹄目来源的轮状病毒的该基因有何关联。RVA/Human-wt/GHA/PML1965/2012/G6P[6]的基因型组合为G6-P-[6]-I2-R2-C2-M2-A2-N2-T2-E2-H2。除了少数布基纳法索和喀麦隆毒株的VP6基因以及几内亚比绍毒株的VP6和NSP4基因外，它在所有基因组片段上都与之前在意大利和非洲检测到的G6P[6]毒株共享亚谱系。G6P[6]毒株的VP7基因似乎源自人G6P[9]毒株的VP7基因，且与偶蹄目G6或人G6P[14]毒株的VP7基因亲缘关系较远。估计G6P[6]毒株VP7序列的最近共同祖先时间为1998年。牛和人G6轮状病毒中VP7基因的进化速率分别为6.93×10^(-4)和3.42×10^(-3)核苷酸替换位点^(-1)年^(-1)，表明在新宿主中存在加速的适应性过程。PML1965其余10个基因组片段的序列与在非洲检测到的具有DS-1样遗传背景的G2和G8人轮状病毒的序列聚类。总之，PML1965由具有DS-1样背景的G2或G8 RVA毒株进化而来，从人G6P[9] RVA而非偶蹄目G6 RVA毒株获得G6 VP7基因。
