Submitted to: Research Workers in Animal Diseases Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 11/9/2003
Publication Date: 11/9/2003
Citation: Grebennikova, T.V., Zaberezhny, A.D., Musienko, M.I., Mengeling, W.L., Lager K.M., Aliper, T.I., Nepoklonov, E.A. 2003. An infectious genomic cDNA clone of the attenuated PRRSV strain of North American porcine reproductive and respiratory syndrome virus. Conference of Research Workers in Animals Diseases. p. 108.
Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is a disease of swine characterized primarily by reproductive failure in pregnant gilts and sows and respiratory tract illness in pigs of all ages. PRRS is caused by porcine reproductive and respiratory syndrome virus (PRRSV), a member of the family Arteriviridae in the order Nidovirales. An infectious virion of PRRSV comprises a single-stranded positive polarity RNA genome that is 5'-capped and 3' polyadenylated. Virion RNA is contained within a nucleocapsid core surrounded by a lipid-containing envelope. Infectious cDNA clones have been described for a number of positive-strand RNA viruses, including a wild-type European and North American PRRSV. A library of full-length cDNA clones of the attenuated (251st passage) PRRSV strain NADC8 was assembled in the plasmid vector pASYS177. Strain NADC8 (251) was derived from the field isolate after 251 passages in cell culture. The capped polyadenylated full-length positive polarity RNA strand was obtained in vitro and used for transfection of BHK-21 and MARC-145 cells. Supernatants from transfected cell monolayers were serially passaged on MARC-145 cells. Recombinant viruses exhibited the same cell tropism as the original virus. Seven progeny viruses were obtained and confirmed by specific immunostaining in serial passages in MARK-145 cells. Three of the 7 clones demonstrated similar growth characteristics as the parental strain. The other 4 clones grew to lower titers after five passages. This model will be used for analysis of the genetic determinants for attenuation and virulence in the PRRSV genome in order to develop of a new-generation of vaccines.