Dynamics Of Neutralizing Antibody In Horse Vaccinated With Attenuated Equine Infectious Anemia Virus Vaccine

An attenuated equine infectious anemia virus(EIAV)vaccine was developed by scientists led by Rongxian Shen of Harbin Veterinary Research Institute in the 1970s.The pandemic of equine infectious anemia(EIA)in China,which caused the death of millions horses,was successfully controlled by the country-wide application of this vaccine from 1980-1990.This vaccine is the first lentiviral vaccine,which elicits broad and effective immunity against the infection of pathogenic strains.To better understand the equine infectious anemia virus(EIAV)attenuated vaccine immune protection mechanism,in this study,the 3 horses were inoculated with vaccine strain EIAVDLV121,then after 6 months challenged with virulent strain EIAVLN40.During the whole process,the body temperature platelet,and plasma viral load were measured.The clinical results showed that the EIAVDLv121 immunized horses had no clinical symptoms and achieved a 100%protection rate,while the horses in the control group that not been vaccinated had typical clinical symptoms of EIA and died.In order to determine the dynamic changes of neutralizing antibodies to equine attenuated vaccine horses,the titer of neutralizing antibody during 6 months after EIAVDLV121 immunization was determined by neutralizing assay using envelops of EIAN FDDV13.After vaccination,the neutralizing antibodies titers in horse immunized with EIAVDLV121 increased gradually and reached the highest value at 6 months,suggesting that neutralizing antibodies might be related to the humoral immunity of equine infectious anemia virus attenuated vaccine.In addition,the study showed that the horses in the control group had pathological changes in the liver and spleen characterized by serious inflammation and necrosis as the main feature after chanllenging,but no obvious pathological changes for the vaccinated horses after challenging.In unvaccinated horses,the viral loads after challenging reached up to 9 591 240 RNA copy/?g,while horses vaccinated had very low virus load(the range from 0?148 RNA copy/?g).This study showed that the vaccine can effectively protect the body against virulent virus challenging.The neutralization antibody may be correlated with immune mature,viral load and clinical pathogenic change.