FPV Infection Investigation And Immunoprophylaxis Study In Captive Siberia Tigers

Feline panleukopenia is a highly contagious viral disease of kittens with a high mortality caused by feline panleukopenia virus(FPV). Not only can FPV infect all members of felid, but also other wild animals are susceptible to infection, such as mustelidae, procyonidae, which severely affects the healthy of the wild large-scale felid in China recently. Vaccination is an effective measure to prevent feline panleukopenia, in order to prevent the occurrence and epidemic of FPV in captive felid, we should comprehensively understand the infection situation of FPV in Siberia tigers and clarify the genetic evolution of epidemic strains, and prepare available vaccine of FPV finally. 92 sera samples and 143 feces samples were dected by HI and PCR separately, then virus isolation techniques were used to detected FPV in fecal samples of tigers. Three pairs of specific primers were designed and used to amplify VP1,VP2 and NS1 genes of FPV-HLJ, the homology of nucleotide and amino acid sequences were analysised on the bases. F81 of cat kidney cell lineage inoculates with FPV-HLJ synchronically. Viral suspension was inactivated by using formaldehyde for 24 h and inactive vaccine was made in such a way that aluminium hydroxide gel was added to the suspension as adjuvant. The inactive vaccine was applied to kitten tigers of two months old hypodermically after protection effect was proved in the test in nonimmunized cats of two months old using the same procedure. The results showed that 55.4% serum samples were HI positive, which indicated that infection of FPV is common in Siberia tigers. And the elimination of toxicant was lasted from November to the next February at least, which results in the environment severe contaminate. FPV-HLJ was successfully isolated by F81 cell line, the full lengths of the VP1,VP2 and NS1 genes of FPV-HLJ are 2256 bp,1755bp and 2007bp, which encode 727,584 and 668 amino acids, with the same lengths as the VP1,VP2 and NS1 gene of standard strain CU-4 of FPV. The study of the genetic evolution indicate that FPV-HLJ has a closer relationship with the domestic strain XJ-1 than CU-4 and the FPV-HLJ was antigen dominance than CU-4, which can be used as vaccine strain. Antibody level in vaccinated cats revealed an increasing trend that the valence of antibody reached 1:1024～2048 after three times of vaccination. A hundred percent vaccinated cats survived challenges of virulent FPV virus. Then two months old nonimmune tigers were inoculated, which can effectively induce the specific immunization against FPV, and the HI titer were 1:1024 mostly 15 days after the third immunity. This study posses considerable theoretical and practical significance for the prevention of FPV and the conservation of wild large-scale felid.