Structural analysis of the US-segment of a viable temperature sensitive human cytomegalovirus mutant

Retinazone inhibits certain blood-borne human viruses including Ebola virus Zaire

BACKGROUND

Human HBV and HIV integrate their retro-transcribed DNA proviruses into the human host genome. Existing antiretroviral drug regimens fail to directly target these intrachromosomal xenogenomes, leading to persistence of viral genetic information. Retinazone (RTZ) constitutes a novel vitamin A-derived (retinoid) thiosemicarbazone derivative with broad-spectrum antiviral activity versus HIV, HCV, varicella-zoster virus and cytomegalovirus.

METHODS

The in vitro inhibitory action of RTZ on HIV-1 strain LAI, human HBV strain ayw, HCV-1b strain Con1, enhanced green fluorescent protein-expressing Ebola virus Zaire 1976 strain Mayinga, wild-type Ebola virus Zaire 1976 strain Mayinga, human herpesvirus 6B and Kaposi's sarcoma-associated herpesvirus replication was investigated. The binding of RTZ to human glucocorticoid receptor was determined.

RESULTS

RTZ inhibits blood-borne human HBV multiplication in vitro by covalent inactivation of intragenic and intraexonic viral glucocorticoid response elements, and, in close analogy, RTZ suppresses HIV-1 multiplication in vitro. RTZ disrupts the multiplication of blood-borne human HCV and Ebola Zaire virus at nanomolar concentrations in vitro. RTZ has the capacity to bind to human glucocorticoid receptor, to selectively and covalently bind to intraexonic viral glucocorticoid response elements, and thereby to inactivate human genome-integrated proviral DNA of human HBV and HIV.

CONCLUSIONS

RTZ represents the first reported antiviral agent capable of eradicating HIV and HBV proviruses from their human host. Furthermore, RTZ represents a potent and efficacious small-molecule in vitro inhibitor of Ebola virus Zaire 1976 strain Mayinga replication.

Identification and expression of human cytomegalovirus transcription units coding for two distinct Fcgamma receptor homologs

Cellular receptors for the Fc domain of immunoglobulin G (IgG) (FcgammaRs) comprise a family of surface receptors on immune cells connecting humoral and cellular immune responses. Several herpesviruses induce FcgammaR activities in infected cells. Here we identify two distinct human cytomegalovirus (HCMV)-encoded vFcgammaR glycoproteins of 34 and 68 kDa. A panel of HCMV strains exhibited a slight molecular microheterogeneity between Fcgamma-binding proteins, suggesting their viral origin. To locate the responsible genes within the HCMV genome, a large set of targeted HCMV deletion mutants was constructed. The mutant analysis allowed the identification of a spliced UL119-UL118 mRNA to encode vFcgammaR gp68 and TRL11/IRL11 to encode vFcgammaR gp34. Both vFcgammaRs are surface resident type I transmembrane glycoproteins. Significant relatedness of sequences in the extracellular chain of gpUL119-118 and gpTRL11 with particular immunoglobulin supergene family domains present in FcgammaR I and FcgammaRs II/III, respectively, indicates a different ancestry and function of gpUL119-118 and gpTRL11. The HCMV-encoded vFcgammaRs highlight an impressive diversification and redundancy of FcgammaR structures.