Comparison of Immunogenecity of Live MDV Vaccine Containing REV-LTR Gene and Commercial Vaccine Strain CVI988/Rispens
A recombinant Marek's disease virus strain(rMDV-LTR strain)was constructed previously by integrating the long terminal repeat(LTR)of reticuloendotheliosis virus(REV)into the genome of the CVI988/Rispens vaccine strain by homologous recombination technology,resulting in high proliferation capibility.In order to compare the immunogenecity of the rMDV-LTR strain and its parental CVI988/Rispens strain,these two vaccines were subcutaneously inoculated to one-day-old SPF chickens with three different doses at napes and necks.On the 7th day after inoculation,Marek's disease virulent rMd5 was used to challenge these chickens and chickens were necropsied after continuous observation for 60 days.Clinical pathological observations found that SPF chicks immunized with rMDV-LTR strain or CVI988/Rispens strain at a dose of no less than 250 PFU/feather provided greater than 80％immune protection.Neither vaccine at a dose of 125 PFU/feather provided more than 80％immune protection.In the rMDV-LTR group,no death occurred only 2 chickens lost weights,and no tumor was found after organ dissection.In contrast,2 chickens died and one of them had a tumor in the CVI988/Rispens group.The immune protection indexs of rMDV-LTR strain and CVI988/Rispens strain were 77.78％and 66.67％,respectively.The results showed that the immune protection rate of rMDV-LTR strain was higher than that of its parent CVI988/Rispens vaccine strain at low doses,suggesting that the recombinant virus rMDV-LTR vaccine strain might be used as a safe and effective new MDV vaccine.
Marek's diseaserecombinant viruslong terminal repeat of reticuloendotheliosis virusprotectionimmunogenecity efficacy
万方数据
维普
