The humoral immune response in guinea pigs primed with recombinant vaccinia virus strains expressing Transmitted/Founder virus HIV-1 membrane proteins and boosted with gp140 protein
Objective 
To analyze the antibody responses in guinea pigs vaccinated with recombinant vaccinia virus(rTT) strains expressing transmitted/founder (T/F) HIV-1 membrane proteins in combination with gp140 protein. 
 
 
Methods 
Guinea pigs were primed with rTT strains and boosted twice with gp140 protein in every four weeks. Serum samples were collected from guinea pigs before immunization and in 2, 6 and 10 weeks after the last immunization for the detection of HIV-1-specific binding antibodies, neutralizing antibodies and the relative avidity of antibodies. 
 
 
Results 
(1) The binding antibodies specific to HIV-1 B′/C, B, AE subtypes were efficiently induced by the immunization of rTT-B, rTT-C and rTT-CON vaccinia strains in combination with gp140 protein. The antibody titers ranged from 111 430 to 1 024 000. More antibodies against HIV-1 B′/C and AE subtypes were induced in guinea pigs by the immunization of rTT-C and rTT-CON strains in combination with gp140 protein than those by using rTT-B strain prime-protein boost strategy (P<0.05). No significant differences with the titers of HIV-1 B subtype specific antibody were observed among the guinea pigs immunized with the three strategies. (2) High titers of SF162 and ZM109 neutralizing antibodies were induced in guinea pigs immunized with rTT-B, rTT-C and rTT-CON vaccinia strains in combination with gp140 protein, ranging from 83.76 to 649.30. No significant differences were found among the three groups. (3) The HIV-1 V1V2-gp70 specific antibodies associated with protective immunity were induced by immunization of the three virus prime-protein boost strategies. No significant differences were observed among them. (4) Antibodies induced in guinea pigs by immunization of the three strategies showed strong affinity to membrane proteins of HIV-1 B′/C, B, AE subtype strains. No significant differences were found among the three immunization strategies. 
 
 
Conclusion 
A strong humoral immune response was induced in guinea pigs primed with recombinant vaccinia virus strains expressing T/F virus HIV-1 membrane proteins and boosted with gp140 protein. 
 
 
Key words: 
HIV; Transmitted/founder virus; Recombinant vaccinia virus; Protein vaccine; Combined immunization