ABSTRACT
<p><b>BACKGROUND</b>Although DNA vaccine is considered as the next generation of vaccine, most DNA vaccine candidates are still suffering from the relatively weak immunogenicity despite the increased dosage of plasmid DNA administered. In order to enhance the immune responses elicited by a codon-optimized HIV gag DNA vaccine, a modified plasmid vector pDRVI1.0 and a booster immunization with replicating Tiantan vaccinia (RTV) strain expressing the same gene were employed.</p><p><b>METHODS</b>Vector pDRVI1.0 was constructed through inserting the 72-bp element from the SV40 enhancer, which was reported promoting nuclear transport of plasmid DNA, to the upstream of cytomegalovirus enhancer/promoter region of the plasmid vector pVR1012. Gene expression levels from expression plasmids based on pDRVI1.0 and pVR1012 were tested. Humoral and cellular immune responses induced by DNA vaccine alone or DNA prime-RTV boost regimen were determined in mice.</p><p><b>RESULTS</b>It was shown that the 72-bp element significantly enhanced the gene expression level in non-dividing cells. gag-specific humoral and cellular immune responses induced by DNA vaccination were both significantly improved, while the Th1/Th2 balance was not obviously affected by the 72-bp element. RTV boosting further significantly enhanced DNA vaccine-primed antibody and T cell responses in a Th1-biased manner.</p><p><b>CONCLUSIONS</b>The 72-bp SV40 enhancer element should be included in the DNA vaccine vector and RTV strain is a very efficient live vector for boosting immunization.</p>
Subject(s)
Animals , Female , Mice , AIDS Vaccines , Allergy and Immunology , Amino Acid Sequence , Blotting, Western , CD8-Positive T-Lymphocytes , Allergy and Immunology , Enhancer Elements, Genetic , Gene Products, gag , Allergy and Immunology , HIV Antibodies , Blood , Immunoglobulin G , Blood , Mice, Inbred BALB C , Molecular Sequence Data , Plasmids , Simian virus 40 , Genetics , Vaccination , Vaccines, DNA , Allergy and Immunology , Vaccinia , Allergy and ImmunologyABSTRACT
<p><b>OBJECTIVE</b>Although HIV-1 infection is prevalent in many regions in China, it remains largely unknown on the biological characteristics of dominant circulating isolates. This study was designed to isolate the circulating viral strains from different prevalent regions and to characterize their biological properties and neutralization sensitivity.</p><p><b>METHODS</b>Primary viruses were isolated from fresh PBMCs using the traditional co-culture method and their capacity of inducing syncytium was tested in MT-2 cells. Meanwhile, their coreceptor usage was determined with two cell lines: Magi and GHOST (3) stably expressing CD4 and the chemokine receptor CCR5 or CXCR4. Furthermore, the sensitivity of these viruses to neutralization by HIV-1-infected patients' plasma which were highly active to neutralize SF33 strain, was quantified in GHOST cell-based neutralization assay.</p><p><b>RESULTS</b>Six primary viral strains were isolated from 4 separated regions. Isolates LTG0213, LTG0214 and XVS032691 induced syncytia in MT-2 cells, and used CXCR4 as coreceptor. Isolates XJN0021, XJN0091, or SHXDC0041 did not induce syncytia, and used CCR5 as coreceptor. Overall neutralization sensitivity differed among four representative strains: HIV-1 XVS032691 > LTG0214 >XJN0091 approximately SHXDC0041.</p><p><b>CONCLUSION</b>The neutralization sensitivity of HIV isolates is linked with the phenotype of isolates, in which syncytium-inducing (SI) or CXCR4-tropic (X4) viruses are more easily neutralized than non-syncytium-inducing (NSI) or CCR5-tropic (R5) viruses. The genetic subtypes based on the phylogeny of env sequences are not classical neutralization serotypes.</p>
Subject(s)
Humans , CD4-Positive T-Lymphocytes , Metabolism , Cell Line , Cells, Cultured , Chemokines , Genetics , Allergy and Immunology , China , Coculture Techniques , Methods , Giant Cells , Virology , HIV Infections , Virology , HIV Seropositivity , Genetics , Allergy and Immunology , HIV-1 , Allergy and Immunology , Physiology , Neutralization Tests , Receptors, CCR5 , Metabolism , Receptors, CXCR4 , Metabolism , Virus ReplicationABSTRACT
<p><b>OBJECTIVE</b>To investigate the immunogenicity of HIV vaccine vTKgpe based on Vaccinia Virus Tiantan vector in mice and rabbits.</p><p><b>METHODS</b>Mice were inoculated with HIV vaccine vTKgpe by intramuscular (i.m.), intradermal (i.d.) or subcutaneous (s.c.) injections. Blood sample were collected every week, and then antibodies against HIV and vaccinia virus vector were detected. At week 4, some mice were killed and cellular immune responses were examined by flow cytometer. Additionally two rabbits were vaccinated subcutaneously, blood sample were tested as done with mice.</p><p><b>RESULTS</b>In mice i.m. and s.c. groups, HIV specific antibodies emerged at week 2 and declined at week 4. Antibodies against vector elevated rapidly at week 4, and potentially affected HIV specific antibody detection. Cellular immune responses were only detected in s.c. group. Serum of rabbit showed that anti-HIV antibody appeared at week 2 and maintained for several weeks.</p><p><b>CONCLUSION</b>Vaccine vTKgpe innoculated by i.m. and s.c routes inclined to induce humoral immune responses in mice, but in i.d. group, inclined to induce cellular immune responses. Response to the recombinant vaccinia virus was more sensitive in rabbit than in mice.</p>