RESUMO
@#Objective To screen the formulation of heat-resistant protective agent for live classic swine fever(CSF) vaccine in order to prolong the preservation time of vaccine under harsh conditions.Methods The heat-resistant protective agent prepared based on the formula containing gelatin,D-sorbitol,trehalose,D casein hydrolysate of different contents was mixed with the live virus antigen of CSF and then lyophilized.The finished products with qualified appearance were screened for routine detection and aging resistance test,and the over-dose(10 and 30 portions) of the products qualified in the aging resistance test were used to immunize piglets via subauricular neck,5 for each to evaluate the safety of the vaccines.Results Among the 6 batches of lyophilized live CSF vaccine,3 batches(20200301,20200302 and 20200303) met the requirements of the current Chinese Veterinary Pharmacopoeia.The lyophilized loss was within 0.04～0.33 titers,and the moisture contents were all less than 2%;20200301 and 20200302 batches of finished products passed the aging resistance test.No adverse clinical symptoms were observed in all piglets 30 min after vaccination;The body temperatures of piglets vaccinated with 10 and 30 doses of vaccine were normal for 14 d after vaccination.Conclusion The two formulations of heatresistant protective agent selected might be used for freeze-dried preparations of live CSF vaccine with good effect of aging resistance and safety to piglets.
RESUMO
The levels of the antibody response against,classic swine fever (CSF) vaccine were measured by blocking ELISA at different time for pigs vaccinated with CSF vaccine (CSFV group,n= 3),pigs inoculated with porcine eircovirus type 2 (PCV2) and with CSF vaccine two weeks later (when PCV2 viremia was detected by PCR,PCV2/CSFV group,n=3),or inoculated with both CSF vaccine and PCV2 at the same time (CSFV/PCV2 group,n=3),respectively.And distribution of genome or antibodies specific to PCV2 of the PCV2 infection group,PCV2/CSFV group and CSFV/PCV2 group were also detected by indirect ELISA or PCR,respectively.The results showed that experimental infection of PCV2 was successful.In pigs inoculated with both PCV2 and CSF vaccine,the antibody response to CSF vaccine was significantly lower than that of animals treated with CSF vaccine vaccination alone at 52 days postinoculation (DPI).The average titers of antibodies against CSFV in animals of CSFV group were obviously higher than those of the PCV2/CSFV or CSFV/PCV2 group at 49 and 52DPI,respectively.The positive rate of antibodies against CSFV in pigs of CSFV group was 100% in comparison with that of animals inoculated with PCV2 and the vaccine (only 67%).The results suggested that the infection of PCV2 could suppress the antibody response to classical swine fever vaccine.