Biological Characteristics of PRRS Virus Strain Kty-Prrs-05 Isolated in Vietnam through Cultured Passages

Abstract

      The PRRSV strain studied in this research was KTY-PRRS-05, isolated from pigs carrying “blue ear” disease (PRRS) from Haiphong city, Vietnam. The cell line of MARC-145 was suitable to isolate PRRS virus. Virus quickly replicated in such cells and caused typical cytopathogenic effect (CPE), i.e cells clumped and sloughed from the bottoms of culture flask. PRRS virus caused CPE in MARC-145 cells as early as 24 hours post inoculation (hpi); after 84hpi, almost of cells were detached from surface of the culture flasks. Viral load could get 105 TCID50/25́l) in each sub-culture passage. Viral load freely released in medium was higher than that inside cells. The viral titer multiplied in MARC-145 cells increased continuously at 48 hours post inoculation, then maximized at 72 hours withlog10 TCID50 of 4,83. In the present research, some biological characteristics, including CPE, viral load, and the growth curve of PRRSV isolates (KTY-PRRS-05) were identified and compared with those of vaccine virus. These results are useful for selecting PRRS virus in production of PRRS vaccine or antigen in development of test kit for diagnosis.