Proteic boost enhances humoral response induced by DNA vaccination with the dnaK gene of Chlamydophila abortus but fails to protect pregnant mice against a virulence challenge

Abstract

-In order to enhance the quantity and the protective properties of the antibodies induced by DNA vaccination with the heat shock protein dnaK gene of Chlamydophila abortus AB7 as well as to elicit an efficient cellular immune response, we vaccinated mice with a DNA prime followed by a boost with the recombinant DnaK protein. In non-pregnant mice, this strategy induced the same predominance of the IgG2a isotype as DNA immunization alone with a substantial increased antibody level. The induced antibodies had no in vitro neutralizing properties on C. abortus infectivity. Moreover, the proteic boost probably failed to elicit an efficient cellular immune response since the pregnant or non-pregnant mice were not protected against the bacterial challenge.DNA immunization / proteic boost / Chlamydophila abortus / DnaK / Hsp70

Vaccination of rainbow trout, Oncorhynchus mykiss (Walbaum), with recombinant and DNA vaccines produced to Flavobacterium psychrophilum heat shock proteins 60 and 70

“…In fish, it has been shown that antibody titres do not always correlate with protection (Ellis 1999) and it is likely that cell mediated immunity also plays a role. Similarly to the current study, vaccination with both Chlamydophila abortus groEL (hsp60) (Hechard, Grepinet & Rodolakis 2004) and DnaK (hsp70) (Hechard, Grepinet & Rodolakis 2003) induced high levels of antibodies in mice, but failed to provide protection against challenge.…”

DNA vaccination against Chlamydiaceae: current status and perspectives

“…Indeed, the DNA vaccination with these genes failed to significantly reduce the abortion cases, as well as the C. abortus quantities in the spleens, placentas, and fetuses of mice after the challenge, especially in comparison with the effect of the temperature-sensitive mutant 1B [68], which protects mice very efficiently against C. abortus and is currently being used as a positive control of immunization. The protein boost with the recombinant DnaK protein substantially increased the antibody level, but as for the two other antigens tested, the induced antibodies had no in vitro neutralizing properties on C. abortus infectivity [31].…”

“…The DNA vaccinal strategy was tested in a pregnant and non-pregnant murine model using genes encoding MOMP [30], Hsps DnaK (Hsp70) [29,31] and GroEL (unpublished results). The experimental protocol was identical for the three genes: outbred OF1 mice were intramuscularly immunized in each tibialis anterior three times at three week intervals and the mice were intraperitoneally challenged with the virulent strain, C. abortus AB7.…”

“…The experimental protocol was identical for the three genes: outbred OF1 mice were intramuscularly immunized in each tibialis anterior three times at three week intervals and the mice were intraperitoneally challenged with the virulent strain, C. abortus AB7. In the case of the DnaK vaccination, a prime-boost strategy was also tested with a third injection consisting of recombinant DnaK protein [31]. Despite a specific humoral response directed against the proteins encoded by the injected vaccinal genes, no significant protection was found.…”

Protective Immunity against Chlamydia psittaci Lung Infection Induced by a DNA Plasmid Vaccine Carrying CPSIT_p7 Gene Inhibits Dissemination in BALB/c Mice

“…The nucleic acid sequences of exogenous vaccine antigens, currently mainly selected subunit vaccine antigens, were inserted into eukaryotic expression vector plasmids containing strong eukaryotic cell promoters to induce expression of the corresponding antigens [ 6 , 7 ]. The research on chlamydial DNA vaccines started in 1997 [ 8 ], and primarily targeted the genes ompA , Pgp3 , and HSP60 [ 9 , 10 , 11 , 12 , 13 ]. Zhang et al constructed the MOMP/pcDNA3.1 eukaryotic expression plasmid.…”