Immunological and biological characteristics of viral isolates of porcine reproductive and respiratory syndrome

: Described in the paper are study results of some immunobiological properties of 5 field isolates of the porcine reproductive and respiratory syndrome virus (PRRSV), obtained in Russia and Byelorussia in 1998-2001. According to the research work, the PRRSV isolates with different immunobiological properties have been circulating in the territories of Russia and Byelorussia. Three of the 4 examined virus isolates were found to be pathogenic and 1 avirulent to pigs.