Comparative virulence of reproductive diseases caused by type 1 (European-like) and type 2 (North American-like) porcine reproductive and respiratory syndrome virus in experimentally infected pregnant gilts.
The aim of this study was to compare the virulence of type 1 and type 2 porcine reproductive and respiratory syndrome virus (PRRSV) as assessed by the level of viral replication, viral distribution and apoptosis in stillborn fetuses and live-born piglets from infected pregnant gilts. Type 1 or type 2 PRRSV was given intranasally to pregnant gilts at 3 weeks before the expected date of parturition. Regardless of virus genotype, PRRSV-infected gilts farrowed between 102 and 109 days of gestation, while control uninfected gilts carried the pregnancy to term and farrowed at 114-115 days of gestation. There were no significant differences in the mean number of virus-infected cells per unit area of tissue when type 1 and type 2 virus infections were compared between stillborn fetuses and live-born piglets. Stillborn fetuses from the type 1 PRRSV-infected pregnant gilts had a significantly higher mean number of apoptotic cells per unit area of thymus (P = 0.013) than those from type 2 PRRSV-infected pregnant gilts. Significant differences in virulence were not observed between types 1 and 2 PRRSV in terms of female reproductive failure, although thymic apoptosis differed in stillborn fetuses from type 1 and type 2 PRRSV-infected pregnant gilts.
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
K
K
Han
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
H W
HW
Seo
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
C
C
Park
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea.
I
I
Kang
Division of Epidemic Intelligence Service, Korea Centers for Diseases Control and Prevention, Osong, Republic of Korea.
S-K
SK
Youn
College of Oriental Medicine, Kyunghee University, 1 Hoegi-dong, Dongdaemun-ku, 130-701 Seoul, Republic of Korea.
S Y
SY
Lee
College of Oriental Medicine, Kyunghee University, 1 Hoegi-dong, Dongdaemun-ku, 130-701 Seoul, Republic of Korea.
S-H
SH
Kim
Department of Veterinary Pathology, College of Veterinary Medicine, Seoul National University, 1 Gwanak-ro, Gwanak-gu, Seoul 151-742, Republic of Korea. Electronic address: swine@snu.ac.kr.
C
C
Chae
D000818:Animals; D004279:DNA, Viral; D005260:Female; D005838:Genotype; D019318:Porcine Reproductive and Respiratory Syndrome / Q000473:pathology / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000472:pathogenicity*; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D013552:Swine; D014774:Virulence
D004279:DNA, Viral
pathogenicity; porcine reproductive and respiratory syndrome virus; reproductive failure; virulence