Recombinant protein production has been widely applied for therapeutic and diagnostic
applications, namely for polyclonal antibody production. Antibodies are usually raised
against a specific protein by immunization of animals with the purified protein. The
bacterium Escherichia coli is one of the most used host cells for the bio-production of
proteins, but it still presents some drawbacks: many proteins of biomedical interest are
difficult to express properly in this host system, resulting in insoluble protein
aggregates. Gene fusion technology has been employed to optimize recombinant protein
production in E. coli. Fusion partners have also been used to potentially increase protein
immunogenicity.
In this work, the overproduction and immunopotentiating properties of a novel fusion
system were studied. Novel fusion tags, Fh8 and H, were fused to five target proteins
with diagnostic interests: CP12, a 12 kDa surface protein from Cryptosporidium parvum
oocysts; CWP, a cyst wall protein from Giardia lamblia; ENT, a surface protein from
Entamoeba histolytica cysts; TgOWP, a Toxoplasma gondii oocyst wall protein; and
Frutalin, a recombinant lectin from Artocarpus incisa seeds. Production yields of all
Fh8-fused proteins, H-fused proteins and non-fused recombinant proteins were
compared and polyclonal antibodies were raised against CP12, CWP and ENT nonfused
and H-fused antigens.
Overall, the results showed that the fusion of both Fh8 and H tags to all target proteins
improved their production in comparison with the respective non-fused target proteins.
Moreover, the H tag efficiently increased CP12, CWP and ENT specific
immunogenicity without being removed from the fusion antigens and without coadministration
of adjuvants, resulting in a more effective and earlier immune response.
The overproduction and immunopotentiating effects observed for this novel fusion
system make it a unique alternative for recombinant protein production in E. coli and
for immunodiagnostic and immunoprophylactic purposes
