Investigation On The Molecular Epidemiology Of Infectious Bursal Disease In Henan Province And Control Of The Disease

The epidemic of infectious bursal disease (IBD) is increasingly complicated and vaccine failure oftern occur in recent years. In order to prevent and control the epidemic of IBD in Henan province, the epidemic situation and the molecular epidemiology of IBD were investigated in 15 areas of Henan province during 2002-2004 years. Some preventing measures that aimed at epidemic of IBD were presented.1. Investigation on the epidemic situation of IBD in Henan provinceThe epidemic situation of IBD was investigated during 2002~2004s in Henan province. The results showed that the incidence season of IBD have all-year trend, but fastigium was among the 6-9 months in a year. The range of day-old of the sicked chicken are increased largely. The main characters of pathological changes are bursa dropsy and surrounding with somewhat as similar as jelly and urate aggradation in kidney , the percentage of the two pathological changes were 67.2% and 73.11%, respectively. The other pathological changes are not typical; The morbidity of immunized chickens were about 78.17%, and the percentage of one flock chickens have come on IBD again were about 16.98%. The range of host and susceptible fowl are increased largely. The incidence reasons have been primary analyzed.2. Investigation on the molecular epidemiology of IBD in Henan provinceIn order to ascertain the reason of IBD epidemic new characteristics, 39 IBDV isolates that isolated from 2002-2004 years in different areas of Henan province were identified, and the VP2 gene were amplified by reverse transcription-polymerase chain reaction (RT-PCR) and sequenced. The results showed that 30 IBDV isolates were all very-virulent IBDV (vvIBDV), but there was a little difference among those 30 isolates. According to VP2 nucleotide and amino acid, the other 9 isolates were neither accord with vvIBDV characteristic, nor attenuated IBDV strain (attIBDV) characteristic, these isolates are attlBDV, which those VP2 gene had been variated. According to the phylogenetic tree, it can be found that the IBDV isolates collected in different area of Henan province were...