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AIDS Res Hum Retroviruses. 2004 Nov;20(11):1157-65.

RC-101, a retrocyclin-1 analogue with enhanced activity against primary HIV type 1 isolates.

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  • 1HIV Immunology and Diagnostic Branch, Division of AIDS, STD, and TB Laboratory Research, National Center for HIV, STD and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.


Rhesus macaques express three theta-defensins (RTDs 1-3), cyclic octadecapeptides with antiviral and lectin-like properties. Corresponding theta-defensin genes exist and are expressed in humans, but a signal sequence mutation prevents the formation of mature theta-defensin peptides. Retrocyclin-1 is a theta-defensin peptide whose precursor is encoded by human theta-defensin pseudogenes. It can protect human peripheral blood lymphocytes from infection by R5 and X4 strains of HIV-1, and provides a molecular template for designing novel antiviral agents. In this study, we used JC53-BL reporter cells to assess the activity of retrocyclin-1 (RC-100) and several analogues against primary HIV-1 isolates, including R5 and R5X4 strains of subtypes A-D, CRF-01_AE, and recombinants. Each analogue differed from retrocyclin-1 by a single amino acid substitution: Gly --> Tyr in RC-106, RC-115, and RC-116, and Arg --> Lys in RC-101. Although the modification in RC-101 was chemically conservative, this peptide was significantly more potent than retrocyclin-1 across the panel of primary isolates. We performed surface plasmon resonance binding studies, using recombinant gp120 and CD4 produced in insect cells. Although RC-100 and RC-101 bound gp120 LAV/IIIB with a K(d) of 30-35 nM, they bound gp120 from CRF-01_AE strains (CM 235 and 93TH975.15) with K(d) values of 200-750 nM. Overall, our findings suggest that clade-related differences in gp120 glycosylation impact the ability of retrocyclin-1 to bind this viral glycoprotein, and modulate the peptides' ability to prevent HIV-1 infection. The performance of RC-101 suggests that additional "engineering" could further enhance the antiviral properties of theta-defensins.

[PubMed - indexed for MEDLINE]
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