Grebennikova T V, Clouser D F, Vorwald A C, Musienko M I, Mengeling W L, Lager K M, Wesley R D, Biketov S F, Zaberezhny A D, Aliper T I, Nepoklonov E A
NARVAC R and D Department, Ivanovski Virology Institute, 123098 Moscow, Russia.
Virology. 2004 Apr 10;321(2):383-90. doi: 10.1016/j.virol.2004.01.001.
Pigs were exposed to three passages of the NADC-8 strain of porcine reproductive and respiratory syndrome virus (PRRSV) to investigate the relationship between genotypic and phenotypic properties. Differences were found in the virulence of the three passages called virulent, intermediate, and avirulent. Avirulent virus was derived by attenuation of virulent virus in cell culture and intermediate virus was derived by passage of avirulent virus in a pig. Nucleotide sequence differences between virulent and avirulent virus consisted of 50 nucleotide changes and a three-nucleotide deletion, and between avirulent and intermediate virus consisted of 8 nucleotide changes resulting in six amino acid changes. Three of these amino acid changes were direct reversions to virulent virus. Genetic changes, especially those seemingly associated with attenuation followed by some degree of reversion to virulence, in ORF1a, ORF1b, and ORF 6 regions of the genome may be involved in the control of PRRSV replication and virulence.
将猪暴露于猪繁殖与呼吸综合征病毒（PRRSV）NADC - 8毒株的三代传代培养物中，以研究基因型与表型特性之间的关系。在称为强毒株、中间毒株和无毒株的三代传代培养物中发现了毒力差异。无毒株病毒是通过在细胞培养中使强毒株病毒减毒而获得的，中间毒株病毒是通过将无毒株病毒在猪体内传代而获得的。强毒株与无毒株病毒之间的核苷酸序列差异包括50个核苷酸变化和一个三核苷酸缺失，无毒株与中间毒株病毒之间的核苷酸序列差异包括8个核苷酸变化，导致6个氨基酸变化。这些氨基酸变化中有3个是向强毒株病毒的直接回复突变。基因组的ORF1a、ORF1b和ORF 6区域中的遗传变化，尤其是那些似乎与减毒相关随后又有一定程度的毒力回复的变化，可能参与了PRRSV复制和毒力的控制。
