Marie Staňková

Unusual Binding Mode of an HIV-1 Protease Inhibitor Explains its Potency against Multi-drug-resistant Virus Strains

Protease inhibitors (PIs) are an important class of drugs for the treatment of HIV infection. However, in the course of treatment, resistant viral variants with reduced sensitivity to PIs often emerge and become a major obstacle to successful control of viral load. On the basis of a compound equipotently inhibiting HIV-1 and 2 proteases (PR), we have designed a pseudopeptide inhibitor, QF34, that efficiently inhibits a wide variety of PR variants. In order to analyze the potency of the inhibitor, we constructed PR species harboring the typical (signature) mutations that confer resistance to commercially available PIs. Kinetic analyses showed that these mutated PRs were inhibited up to 1,000-fold less efficiently by the clinically approved PIs. In contrast, all PR species were effectively inhibited by QF34. In a clinical study, we have monitored 30 HIV-positive patients in the Czech Republic undergoing highly active antiretroviral therapy, and have identified highly PI resistant variants. Kinetic analyses revealed that QF34 retained its subnanomolar potency against multi-drug resistant PR variants. X-ray crystallographic analysis and molecular modeling experiments explained the wide specificity of QF34: this inhibitor binds to the PR in an unusual manner, thus avoiding contact sites that are mutated upon resistance development, and the unusual binding mode and consequently the binding energy is therefore preserved in the complex with a resistant variant. These results suggest a promising route for the design of second-generation PIs that are active against a variety of resistant PR variants.

Seroprevalence of HHV 8 antibodies among the general population and HIV positive persons in the Czech Republic.

BACKGROUND The seroprevalence rates of herpesvirus 8 (HHV 8) antibodies were determined for the general Czech population and HIV-positive individuals. OBJECTIVES Six hundred and sixty six serum samples from the general Czech population and 129 serum samples from HIV-positive persons were tested for the presence of antibodies to the HHV 8 lytic and latent antigens. STUDY DESIGN HHV 8 antibodies were detected by the indirect immunofluorescence test. RESULTS In the general Czech population, only 2.4 and 0.3% of the serum samples tested positive for antibodies against the lytic and latent HHV 8 antigens, respectively. As many as 34.9 and 10.9% HIV positive individuals had antibodies to the HHV 8 antigens, respectively. Only three of them have developed Kaposis sarcoma (KS) to date. At the time of KS diagnosis, the three patients had antibodies to both HHV 8 antigens. HIV-positive homo/bisexuals were at significantly higher risk of acquiring HHV 8 infection compared with HIV-positive heterosexuals. The increase in HHV 8 seroprevalence was associated with progression of the HIV infection from stage A to stage B. No correlation was found between the HHV 8 seroprevalence and CD 4+T-lymphocytes counts or the HIV viral load. CONCLUSIONS Among the general Czech population, the HHV 8 seroprevalence is as low as in the West European countries. The mean HHV 8 seroprevalence rate in HIV-positive individuals was 34.9% and was comparable with those reported in other low seroprevalence countries.

Prevalence and Incidence of Toxoplasma Infection in HIV-Positive Patients in the Czech Republic

TOXOPLASMOSIS is a major opportunistic infection infecting approximately 30% of the Czech general population (Petersen, Pollak, and Reiter-Owona, 2001). In people with latent toxoplasmosis, who subsequently become infected with HIV, the Toxoplasma infection in the latent form proceeds as such. Less frequently, a patient is first infected with HIV and then with Toxoplasma. However, deterioration of the immune system (usually with a decline of CD4 T-lymphocyte counts under 100/ml) can result in recrudescence of latent infection along with the development of clinically manifest toxoplasmic encephalitis or extracerebral toxoplasmosis. Since toxoplasmosis in HIV patients is a dynamic process, sometimes gradual and other times overtly progressive, only a single examination might not be sufficient. A long-term follow-up is necessary for understanding antibody responses and its relation to clinical and epidemiological parameters. In our study, we had the unique opportunity of following the serological and clinical parameters of 626 patients (i.e. 71% of all Czech HIV-infected persons) from 1988 to 2006 (Pospı́šilová et al. 1997; Sýkora, Zástěra, and Staňková, 1992). Hence we compared the prevalence and incidence data of these patients with the situation in the general population and point out the risks of Toxoplasma infection.