The Epidemiological Surveillance Of PRRSV And PRV Of "Pig High Fever Disease" In Guangdong Province

Pig high fever disease swept China in most intensive pig faming area since 2001. The high morbidity and mortality rates of this disease greatly imperilled the pig farming industry. However, the complexity of possible trigger pathogens is still under dispute. In this study, materials from high fever-prone areas are isolated, cultured in several cell lines, and analysis by molecular epidemiology survey. Our results show that:Serological results of PRRSV and PRV in Guangdong Province. In the samples which collected from 2004 to 2006 in Pearl River Delta, northern, western and eastern earas of Guangdong Province, the total PRRSV positive rate is 48.5 percent. Among them, specimens in the Pearl River Delta region have the highest positive rate of 22.0 percent, while specimens in Western Guangdong have the lowest rates of 15.9 percent. Northern and eastern parts of Guangdong have a positive rate of 19.4% and 18.9% seperately, which stands in the middle of the four provinces. All the data suggeste that porcine reproductive and respiratory syndrome virus is widespread in farms of Guangdong Province, which advises strengthen measurements to be taken to prevent and control the infection.Separation of PRV GDSH virus strain. A suspicional pseudorabies virus (PRV) strain, which isolated from a pig farm in Sihui Guangdong, was amplified by PCR, and measured by infectivity and animal test. It showed typical pathological changes in canine kidney cells (MDCK), Pig Kidneys cell lines (PK-15), and hamster kidney cells (BHK-21). TCID50 in MDCK cells is 10-8/0.1 mL; 56℃30 minutes inactivation; virus inoculated mice and pigs get a typical pseudo-rabies symptoms, itching to death; PCR DNA which isolated from the virus infection in mice with specific primers gets typical 262 bp fragment of Pseudorabies GD virus genes. All the data show that the isolated virus belong to pseudo-rabies virus, which is then named GDSH strain. PRV from the pathogen has proved to be widely spread in Guangdong Province.PRV g-E gene cloning and sequence analysis. Results showes that virus from the Sihui Guangdong pig farm contains a PRV wild strain, named GDSH strain here. The PCR product of this virus is about 1.7 kb, and the homology of its nucleotide sequence is about 98.3% to 99.9% to other PRV strains. Compared with PRV Ea, the homology reaches 99.9 percent. In conclusion, PRV isolated in Guangdong did not mutate remarkbly.