Ridpath J F, Bolin S R
National Animal Disease Center, USDA, Agricultural Research Service, Ames, Iowa 50010, USA.
Virology. 1995 Sep 10;212(1):259-62. doi: 10.1006/viro.1995.1480.
Bovine viral diarrhea viruses (BVDV) are segregated into two genotypes, BVDV 1 and BVDV 2. Viruses within both genotypes may exist as one of two biotypes, cytopathic or noncytopathic. A highly fatal form of BVDV termed mucosal disease (MD) occurs when an animal persistently infected with noncytopathic BVDV becomes superinfected with cytopathic BVDV. In this study, we characterized a noncytopathic (BVDV2-125nc)/cytopathic (BVDV2-125c) viral pair isolated from an animal that died of MD 3 months after vaccination with modified-live BVDV1-NADL. In comparison to BVDV2-125nc, BVDV2-125c contained a 366-nucleotide insertion. The insertion was in the correct reading frame for the large open reading frame of the BVDV genome and occurred in the portion of the genome that codes for the p125 viral polypeptide. There was a 99% identity between the inserted sequences found in BVDV2-125c and sequences from the vaccine virus BVDV1-NADL. These data suggest that MD was induced after a recombination between noncytopathic BVD2-125nc and cytopathic vaccine virus BVDV1-NADL created the cytopathic virus BVDV2-125c.
牛病毒性腹泻病毒（BVDV）分为两个基因型，即BVDV 1和BVDV 2。两种基因型的病毒都可能以两种生物型之一存在，即细胞病变型或非细胞病变型。当动物持续感染非细胞病变型BVDV后又被细胞病变型BVDV超感染时，就会出现一种称为黏膜病（MD）的高度致命形式的BVDV。在本研究中，我们对从一头在接种改良活BVDV1-NADL疫苗3个月后死于MD的动物身上分离出的非细胞病变型（BVDV2-125nc）/细胞病变型（BVDV2-125c）病毒对进行了特征分析。与BVDV2-125nc相比，BVDV2-125c含有一个366个核苷酸的插入片段。该插入片段位于BVDV基因组大开放阅读框的正确阅读框内，且发生在基因组中编码p125病毒多肽的部分。在BVDV2-125c中发现的插入序列与疫苗病毒BVDV1-NADL的序列之间有99%的同一性。这些数据表明，非细胞病变型BVD2-125nc与细胞病变型疫苗病毒BVDV1-NADL之间发生重组产生细胞病变型病毒BVDV2-125c后诱发了黏膜病。
