犊牛腹泻粪便样本中纽布病毒VP1和RNA依赖性RNA聚合酶基因的序列分析

纽布病毒（Nebovirus，NeV）是国内犊牛腹泻的新发病原，其VP1蛋白含有受体结合位点和中和抗原表位，与病毒的感染和免疫密切相关，本研究旨在分析VP1基因1.2型毒株的分子特征。采用RT-PCR方法，对2019年宁夏和河南的犊牛腹泻粪便样本进行NeV检测，扩增阳性样本完整的主要衣壳蛋白（VP1）和RNA依赖性RNA聚合酶（RdRp）。结果显示，宁夏和河南地区NeV检出率分别为11.32%和8.62%。从4个样本中成功获得了1.2型毒株完整VP1和RdRp序列。4个完整VP1与GenBank中73个完整VP1的氨基酸相似性为75.4%~97.8%；与GenBank中仅有的3个1.2型VP1相比，4个毒株在P2区有1个共同的氨基酸突变，在P1区有2个共同的氨基酸突变。与国内基因1.1型、1.3型和1.4型毒株相比，在P2区分别有9、18和14个共同的氨基酸突变，在P1区分别有2个共同的氨基酸突变，在S区分别有1个共同的氨基酸突变。4个完整RdRp均为NB-like基因型，与GenBank中8个完整RdRp的核苷酸相似性为67.2%~94.8%。本文首次在我国检测到VP1基因1.2型毒株，成功获得了4条基因1.2型毒株的完整VP1和RdRp序列，为国内NeV的分子流行病学和遗传进化研究等提供了参考。

Sequences Analysis of Nebovirus VP1 and RNA-dependent RNA Polymerase in Fecal Samples from Calf with Diarrhea

Nebovirus (NeV) is an emerging diarrhea-causing pathogen in calves in China. Its VP1 protein contains receptor binding sites and neutralizing antigen epitopes, which are closely related to virus infection and immunity. The purpose of this study was to analyze the molecular characteristics of VP1 genotype 1.2 strains. In this study, diarrhea fecal samples of calves were collected from Ningxia and Henan in 2019 for detecting NeV by RT-PCR, and the complete major capsid proteins (VP1) and RNA-dependent RNA polymerase (RdRp) were amplified from tested positive samples. The results showed that the NeV detection rates in Ningxia and Henan were 11.32% and 8.62%, respectively. The complete VP1 and RdRp sequences of genotype 1.2 were successfully obtained from 4 positive samples, which shared 75.4%-97.8% amino acid identity with 73 complete VP1 sequences available in GenBank. Compared with all other 3 VP1 of genotype 1.2 in GenBank, the 4 strains in this study shared 1 identical amino acid variation in P2 domain and 2 identical amino acid variations in P1 domain. Compared with genotype 1.1, 1.3 and 1.4 strains from China, the 4 strains shared 9, 18 and 14 identical amino acid variations in P2 domain, respectively, and shared 2 identical amino acid variations in P1 domain and 1 identical amino acid variations in S domain, respectively. The 4 complete RdRp sequences in this study were NB-like genotype and shared 67.2%-94.8% nucleotide identity with all other 8 complete RdRp sequences in GenBank. This is firstly detection of VP1 1.2 genotype NeV strains in China, and 4 complete VP1 and RdRp sequences of genotype 1.2 strains were successfully obtained, contributing to better understanding molecular prevalence of NeVs.