Attenuation of a virulent North American porcine reproductive and respiratory syndrome (PRRS) virus isolate on CDl63-expressing cell lines, and demonstration of efficacy against a heterologous challen

摘要

The discovery of the CD 163 PRRSV receptor in 20041 has permitted the development of PRRS-permissive cell lines from various species. Attenuation of virulent field viruses on these cell lines has the potential to yield new modified live vaccine viruses that differ from existing monkey-cell attenuated vaccines. In one such example, the virulent genotype 2 US strain PI29 was isolated directly from serum on a recombinant CD 163-expressing pig kidney cell line. Following adaptation/attenuation for 24 passages, this virus was evaluated in a small study in which it showed satisfactory safety and efficacy against a heterologous challenge in a young pig respiratory model (Study 42259). Beginning at passage 31 the virus was adapted to a more manufacturing-friendly CD 163-expressing cell line, derived from the baby hamster kidney cell line BHK21. With additional rounds of passaging, viral titers increased. At passage 57 the vaccine virus was evaluated for efficacy in a dose-titration study (Study 32890).