ABSTRACT
We have previously evaluated a Semliki Forest virus (SFV) replicon vectored DNA vaccine (pSFV1CS2-E2) and a recombinant adenovirus (rAdV-E2) expressing the E2 glycoprotein of classical swine fever virus (CSFV) in pigs. The results showed that the immunized pigs were protected from virulent challenge, but few pigs showed short-term fever and occasional pathological changes following virulent challenge. To enhance the immunogenecity of the vaccines, we tried a prime-boost vaccination strategy using a combination of prime with pSFV1CS2-E2 followed by boost with rAdV-E2. The results showed that all the immunized pigs developed high-level CSFV-specific antibodies following prime-boost immunization. When challenged with virulent CSFV, the immunized pigs (n = 5) from the heterologous boost group showed no clinical symptoms, and CSFV RNA was not detected following challenge, whereas one of five pigs from the homologous boost group developed short-term fever and CSFV RNA was detected. This demonstrates that the heterologous prime-boost vaccination regime has the potential to prevent against virulent challenge.
Subject(s)
Animals , Adenoviridae , Genetics , Metabolism , Adenovirus E2 Proteins , Genetics , Allergy and Immunology , Classical Swine Fever , Allergy and Immunology , Classical Swine Fever Virus , Genetics , Allergy and Immunology , Genetic Vectors , Immunization, Secondary , Replicon , Genetics , Semliki forest virus , Genetics , Metabolism , Swine , Vaccines, DNA , Allergy and Immunology , Viral Envelope Proteins , Genetics , Metabolism , Viral Vaccines , Allergy and ImmunologyABSTRACT
Classical swine fever (CSF), caused by classical swine fever virus (CSFV), has been epidemic or endemic in many countries, and causes great economical losses to pig industry worldwide. Attenuated vaccines (such as C-strain) have played an important role in the control of CSF. Recently some new phenomena appear, such as atypical and persistent infections of CSF, immunization failure and so on. Meanwhile, eradication programs have been implemented in many countries, restricting the widespread applications of attenuated vaccines. Thus, currently the priority is to strengthen the research in pathogenesis and transmission mechanisms, as well as to develop marker vaccines. Recently, the applications of reverse genetics technology open up a new way for research of structure and function of CSFV proteins and development of novel vaccines against CSF. This review focuses on the progress of applications of reverse genetics in the functional analysis and marker vaccine development of CSFV, and also discusses the problems confronted now and prospective aspects in the study of CSFV.
Subject(s)
Classical Swine Fever Virus , Genetics , Cloning, Molecular , Genetics, Microbial , Methods , RNA, Viral , Genetics , Recombination, Genetic , Vaccines, Synthetic , Allergy and Immunology , Viral Vaccines , GeneticsABSTRACT
A H5N2 subtype avian influenza virus isolated from goose belongs to highly pathogenic avian influenza virus, and the intravenous pathogenicity indexes (IVPI) =2.99. But ducks are not sensitive to this isolated influenza virus. The virus can infect mouse but only replicates in lung and has no pathogenicity. HA and NA gene of this isolated strain share 99.4% and 99.8% nucleotide sequence identity to the HA gene of A/chicken/Hubei/ 489/2004 (H5N1) and the NA gene of A/chicken/Jilin/53/01 (H9N2), and share 99.3% and 99.6% amino acid sequence identity to the HA protein of A/chicken/Hubei/489/2004 (H5N1), A/swan/Guangxi/307/2004 (H5N1), A/wild duck/ Guangdong/314/2004(H5N1), A/chicken/Henan/210/2004(H5N1) and the NA protein of A/chicken/ Jilin/53/01 (H9N2). There are several continuous basic amino acids (-RRRKKR-) at the cleavage site of HA protein. Phylogenetic trees analysis of HA and NA gene suggests that the isolated influenza virus probably originated from the reassortment of H5N1 and H9N2 subtype influenza virus.