Mycobacterial codon optimization of the gene encoding the Sm14 antigen ofSchistosoma mansoniin recombinantMycobacterium bovisBacille Calmette-Guérin enhances protein expression but not protection against cercarial challenge in mice

Abstract

A mycobacterial codon-optimized gene encoding the Sm14 antigen of Schistosoma mansoni was generated using oligonucleotide assembly. This synthetic gene enhanced approximately fourfold the protein expression level in recombinant Mycobacterium bovis Bacille Calmette-Guérin (rBCG) when compared to that obtained using the native gene in the same expression vector. Immunization of mice with rBCG expressing Sm14 via the synthetic gene induced specific cellular Th1-predominant immune responses, as determined by interferon-gamma production of Sm14-stimulated splenocytes, which were comparable to those recorded in animals immunized with an rBCG strain expressing the native gene. Administration of a single dose of the rBCG-Sm14 construct carrying the synthetic gene conferred protection against cercarial challenge in outbred Swiss mice, at a level equivalent to those provided by either a single dose of rBCG expressing the native gene or three doses of Escherichia coli-derived recombinant Sm14. Our data demonstrated that despite improving the level of antigen expression, the codon optimization strategy did not result in enhanced immunity or protection against cercarial S. mansoni challenge.

Functional expression of the Flp recombinase in Mycobacterium bovis BCG

“…Indeed, the result that the codon-usage adapted flp m gene confers a much higher recombination efficiency both in M. smegmatis and M. bovis BCG than the flp e gene of S. cerevisiae, strongly indicates that mRNA transcribed from the flp e gene of S. cerevisiae was not efficiently translated in both organisms. This is consistent with previous observations that codon usage adaptation improved the expression of other heterologous genes with low G + C content in mycobacteria, such as Sm14 antigen of Schistosoma mansoni (Varaldo et al, 2006) and human immunodeficiency virus type 1 Gag (Kanekiyo et al, 2005). Taken together, these studies indicate that codon usage adaptation may be a generally useful approach to increase expression of heterologous genes in mycobacteria.…”

Current Status of Vaccines for Schistosomiasis

“…Once efficacy has been proven with Freund's adjuvants, other adjuvants, particularly those that are licensed (or have the potential for licensing) for human use, should be used to formulate an antigen. Less conventional or less widely used approaches have been explored as adjuvants for schistosome vaccines, including live Salmonella (113), tetanus toxin (2), filamentous phages (124), recombinant Mycobacterium bovis BCG (151,152), nanoparticles (46), and various methods of mucosal delivery (88,121,140).…”

Plasmid instability when the <i>hsp</i>60 gene promoter is used to express the protective non-toxic fragment B of the diphtheria toxin in recombinant BCG

“…The genetic modification of the BCG vaccine as an approach to the development of new multivalent vaccines has been actively pursued ever since it was proposed in 1989 [8] and has been the focus of our research over the last years [21][22][23][24][25][26][27][28]. BCG is a powerful candidate to a multivalent vaccine platform.…”