Application Of Fluorescent Antibody Viral Neutralization Antibody Assay In Rabies Vaccine Development And Vaccination Surveilance

Rabies is an important zoontic infectious viral disease, epidemic in canivoreas and wildlife,which is caused by rabies virus. Its spillover to human and other domestic animals during itstransmission occurred worldwide, and globly, about55000cases are recorded annually, of which.2000-3000cases occur in China, ranking the second among all the countries. Human rabiescases are also among the first3diseases of notifiable I, II diseases in China.The key to preventing rabies is to vaccinate the susceptible animals. Immunizationcoverage is a crucial index to evaluate the effect of vaccination. In China,3kinds of animalinduding dog, cats and wildlife are infectious sources of rabies. Different kinds of animals needsdifferently designed vaccines such as inactivated, recombinant or live vaccines. Therefore, themethods to evaluate their efficacy are not completely the same. Hence, by assaying theneutralizing antibody level of different individuals, the immunity duration can be determined.Firstly, in our study, a monoclonal antibody to the rabies virus nucleoprotein was preparedand labeled with FITC, reference sera were made from vaccinated dogs and monitored in areference lab. We established the fluorescent antibody virus neutralization (FAVN) and haveassayed the efficacy of a newly developed vaccine with new adjuvant for cat, and monitored theneutralizing antibody level in cats, and also in vaccination campaigns in different regionsincluding cities and rural areas, and identified the individual neutralizing antibody level for petstending fo international transportantion.By utilizing FAVN, we have determined the efficacy of the newly developed inactivatedrabies vaccine for cats, and it was shown to be more than3.0IU/dose; the neutralizing antibodyin cats was16.04±4.29IU/ml averagely14days post inoculation (dpi),37.13±6.12IU/ml，28dpi,21.01±7.61IU/ml56dpi,6.71±3.44IU/ml180dpi，2.66±2.01IU/ml360dpi. These levels are highenough to resist challenge.Secondly, based on the established FAVN, we have monitored the collective serum samplesfor their neutralzing antibody levels in vaccination campaigns. The results showed that, indifferent rural areas, the immunization coverage ranged from0.98-28.9%. The immunizationcoveage in Beijng and Shenzhen were all over70%. The level and immunization coverage in Shenzhen and Beijing both are significantly higher than those from Guangdong, Wuhan andHebei. These results provide useful surveillance data of vaccination and provide importantinformation for directing rabies prevention for local agency.Finally, we utilized the FAVN to identify the immuninzation status of pets for interationaltransportation, all the pet sent for inspection have rabies neutralizing antibody≥0.5IU/ml, theseroconversion is100%, as all the owners have their dogs vaccinated before inspection usingdifferent vaccines. The results also showed that both the imported inactivated rabies vaccine anddomestic vaccine induced similar immune response.All the above demonsttated that FAVN can not oly be used for antibody surveillance ofvaccinated animals, but also be used for vaccine efficacy assay, this has expanded its applicationfield and, FAVN is an important and valuable antibody detection thechnique.