Identification Of The Pathogen Of Silkworm Virus Disease In Yunnan Province And Pcr Detection Technology

Bombyx mori virus disease is one of the more serious diseases in sericulture nowadays, and occurres in every sericultural area all of the country. Its damage-condition is different in each area due to the difference in the geographic envieronment, in the level of rearing-technique and in the rearing way. Yunnan Province lies to the southwest border in China, the climate of season wind is apparent, the shape and appearance of the earth are complicated, forming the special solid climate. The history to rear silkworm is long in Yunnan date from 1000 years before, but the scale to rear silkworm has been always small. During recent several years, the sericultural industry in Yunnan has been gradually put an important position with the adjustment of industrial structure, its production has steadily raised , but in the same time the damage of Bombyx mori virus disease has been increasing with the development of the sericultural industry and the variety of rearing envieronment. In view of these facts, we launched the study on Bombyx mori virus disease.Based on the distribution of sericultural areas in Yunnan, we investigated twelve typically sericultural areas. The results showed, Bombyx mori virus disease occurred in each sericultural area in various degree during seasons to rear silkworms in a year, and it has become one of the key factors to affect the single production of silkworm cocoon. Three main silkworm viruses distribute in every sericultural area, that is Bombyx mori nuclear polyhedrosis virus, Bombyx mori cytoplasmic polyhedrosis virus and Bombyx mori flacherie virus(or Bombyx mori densonucleosis virus). Bombyx mori nuclear polyhedrosis virus disease has the most extensive distribution and is the most serious disease in the occurred diseases. The distribution, the damage degree and the occurring rule of Bombyx mori virus disease initially found out. The results would be benefit to analyzing and preventing and curing the damage of Bombyx mori virus disease.Twelve couples of the virus-samples were detected by using EM in order to identify their classification. Bombyx mori viruses are diagnosed and analyzed on morphology. There were 17 samples of BmNPV , 3 samples of BmCPV and 4 samples of BmFV(or BmDNV) in these samples. The sizes of viruses under EM are basically conformed to the documents' . The results showed, there were three kinds of Bombyx mori viruses in sericultural areas at least: BmNPV, BmCPV and FV(or DNV), and BmNPV diaease was the most serious disease inthree kinds. Observing the characteristics that polyhetrons dissolve in soda solution showed that the fresh polyhetrons are easy to dissolve in soda solution, it is possible that the formation of the V-shape viruses would be related to the alkaline concentration and the time length to handle. In the same condition, cytoplasmic polyhetrons are more hard to dissolve than nuclear polyhetrons . Analysing the shape of polyhetrons under EM showed that the polyhetrons have different mutants. The size of nuclear polyhetrons is more uniform than the cytoplasmic polyhetrons' on the whole. The tetragonal mutant of cytoplasmic polyhetron is bigger than the hexagonal polyhetron in size.Bombyx mori nuclear polyhedrosis vims disease, which is caused by infecting silkworm with BmNPV, is the most damaging disease in every sericultural area in Yunnan Province. It is important to explore and develop the new technology detecting BmNPV for preventing and curing BmNPV disease, and enriching the studying content. Polymerase chain reaction(PCR) is a new technology quickly amplifying tiny amount of DNA. Two couples of primers were designed and synthesized according to the DNA sequences of polyhedrosis protein gene and plO gene from BmNPV, and the DNA of BmNPV was amplified separately by PCR. The results showed a specific amplified band respectively and one of the DNA fragment was about 289 bp, another was about 742bp, which conformed to the expected aim-fragment . The results indicated that the designed primers could be used to detect the infection from BmNP...