The microbicide cyanovirin-N expressed on the surface of commensal bacterium Streptococcus gordonii captures HIV-1.
OBJECTIVE
To explore the feasibility of expressing the potent HIV-inactivating protein, cyanovirin-N (CV-N), in the human commensal bacterium Streptococcus gordonii, as a possible approach for local delivery of CV-N to prevent sexual transmission of HIV-1.


METHODS
To express CV-N in S. gordonii, we used the host-vector system we had previously developed. CV-N was expressed as a fusion protein both attached to the bacterial surface and secreted in soluble form in the supernatant of liquid cultures. The soluble form of recombinant CV-N was tested for gp120-binding activity in an enzyme-linked immunosorbent assay, whereas S. gordonii strain expressing CV-N on the surface was analyzed in an in vitro HIV capturing assay.


RESULTS
Two recombinant S. gordonii strains secreting or displaying CV-N on the bacterial surface were constructed and the expression of CV-N was confirmed by immunoblot and flow-cytometric analysis. The secreted form of recombinant CV-N exhibited a concentration-dependent binding to the envelope glycoprotein gp120 of HIV-1, whereas CV-N displayed on the bacterial surface was able to capture HIV virions efficiently.


CONCLUSIONS
The anti-HIV protein CV-N in S. gordonii was expressed in a biologically active form. This represents a first step in the development of a system to deliver and maintain an effective concentration of a microbicide in the vaginal mucosa.
Laboratory of Molecular Microbiology and Biotechnology, Department of Molecular Biology, University of Siena, Siena, Italy.
Barbara
B
Giomarelli
Roberta
R
Provvedi
Francesca
F
Meacci
Tiziana
T
Maggi
Donata
D
Medaglini
Gianni
G
Pozzi
Toshiyuki
T
Mori
James B
JB
McMahon
Roberta
R
Gardella
Michael R
MR
Boyd
D001426:Bacterial Proteins / Q000096:biosynthesis / Q000378:metabolism*; D002352:Carrier Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D005434:Flow Cytometry; D015699:HIV Envelope Protein gp120 / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D015151:Immunoblotting; D011485:Protein Binding; D015202:Protein Engineering; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000096:biosynthesis; D013291:Streptococcus / Q000378:metabolism*
D001426:Bacterial Proteins; D002352:Carrier Proteins; D015699:HIV Envelope Protein gp120; D011993:Recombinant Fusion Proteins; C107733:cyanovirin N