Highly Virulent Porcine Reproductive and Respiratory Syndrome Virus Emerged in China

Abstract

A highly pathogenic pig disease emerged in China in 2006, which was characterized by prolonged high fever, red discoloration of the body, and blue ears associated with high mortality. Porcine reproductive and respiratory syndrome virus (PRRSV) was isolated as the single most prominent virus in the samples collected from affected pigs. The full-length genomic sequence of the virus revealed two distinct deletions in the non-structural protein 2 (NSP2) in comparison to all previously reported North American genotype PRRSV. Through extensive surveys in 14 different provinces, 56 additional PRRSV isolates were obtained from affected farms. All of the isolates were found to contain identical deletions in NSP2. To confirm the etiology, eight 60-day-old PRRSV-free pigs were divided into two groups and the test group was intranasally infected at a titer of 2 x 10(5.0) tissue culture infectious dose 50 per pig. The inoculated pigs all died at 7, 8, 12, 16, or 21 days post-inoculation with their clinical and pathological findings similar to those in the field. The viruses recovered from dead pigs were identical to the inoculated virus in NSP2 and GP5 genes. Our study shows that the recently emerged PRRSV in China is characterized by two discontiguous deletions in NSP2 and is the cause for the current epizootics in China.

Porcine reproductive and respiratory syndrome virus: Genetic diversity of recent British isolates

“…The disease remains a significant problem worldwide, with a considerable economic impact for affected producers, due to increased mortality, treatment costs, and reduced weight gain and fertility (Neumann et al, 2005). More pathogenic variants have been described in the past, and since 2006, a highly pathogenic form of the virus has been circulating in China and other parts of Asia, causing a devastating economic impact (Zhou et al, 2008).…”

Porcine reproductive and respiratory syndrome virus entry into the porcine macrophage

“…PRRSV causes considerable production losses as infection with the virus can result in severe reproductive and respiratory disorders in pigs (Neumann et al, 2005). With the recent outbreaks of highly virulent variants of the virus in China (Li et al, 2007;Tian et al, 2007;Zhou et al, 2008), interest in PRRSV has increased greatly and the demand for safe and effective vaccines for PRRSV control is higher than ever.…”

“…PRRSV causes considerable production losses as infection with the virus can result in severe reproductive and respiratory disorders in pigs (Neumann et al, 2005). With the recent outbreaks of highly virulent variants of the virus in China (Li et al, 2007;Tian et al, 2007;Zhou et al, 2008), interest in PRRSV has increased greatly and the demand for safe and effective vaccines for PRRSV control is higher than ever.The PRRSV virion consists of a nucleocapsid, composed of a positive-strand RNA genome (±15 kb) and the nucleocapsid protein (N), which is surrounded by a lipid bilayer envelope Dea et al, 1995;Mardassi et al, 1994;Meulenberg et al, 1993;Spilman et al, 2009;Wensvoort et al, 1992). The viral envelope contains six structural proteins: the small envelope protein E, the membrane protein M and the N-glycosylated glycoproteins GP 2 (or GP 2a ), GP 3 , GP 4 and GP 5 .…”

The 30-Amino-Acid Deletion in the Nsp2 of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus Emerging in China Is Not Related to Its Virulence

“…It has been verified that an unparalleled large-scale, atypical PRRS outbreak in China in 2006 was caused by a highly virulent PRRSV strain with a unique 30-amino-acid (30-aa) deletion in its Nsp2-coding region (23,41,48). The question of whether the deletion in PRRSV Nsp2 is related to its virulence and pathogenicity is becoming an interesting one.…”