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Aim: Comparative assessment of effectiveness of serologic methods for toxoplasmosis diagnostics in patients with HIV-infection., Materials and Methods: Sera and CSF samples from 166 patients with AIDS stage IIIB were tested for antibodies to Toxoplasma gondii by indirect immunofluorescence, ELISA and immunoblotting. Results of serological tests were compared with clinical, pathological data as well as with results of MRI and PCR., Results: Clinical value of IgG detection in blood and CSF by ELISA was shown--high level of antibodies marked reactivation of the invasion. IgG antibodies in CSF were detected only if high levels of IgG were present in the blood. Detection of antigenic determinants with molecular mass 18 - 20 and 65 - 70 kDa in immunoblotting was proposed as a criterion of cerebral toxoplasmosis reactivation., Conclusion: Complex laboratory serologic tests along with data obtained by MRI, PCR and microscopy of T. gondii cysts enhances the effectiveness of toxoplasmosis diagnostics. Knowledge of toxoplasmosis reactivation criteria in patients with AIDS will allow to develop the optimal protocol of toxoplasmosis diagnostics and substantiate measures for its prevention.

Aim: To study virulence of Toxoplasma gondii strain isolated from pathologicoanatomic brain tissue of HIV-infected patients on in vivo model as well as immune response to the pathogen in immunocompetent animals and in animals with cyclophosphamide-induced areactivity., Materials and Methods: Groups of immunocompetent and immunodeficient mice were inoculated with cysts of T. gondii obtained from brain tissues of deceased HIV-infected patients. Parasites were detected in different organs and tissues by PCR as well as by parasitological and histological methods. Antibodies to T. gondii belonging to isotypes IgG, IgG1, IgG2, IgA were detected by immunofluorescence assay., Results: Cysts of the pathogen located predominantly in animals' brain, and more rarely - in spleen and liver. Using detection of antibodies of different isotypes, which marked stage of invasion, dynamics of humoral response during persistence of toxoplasms in organism was determined. Analysis of disease pathogenesis as well as peculiarities of immune response to the pathogen in immunocompetent animals and in animals with cyclophosphamide-induced areactivity was performed., Conclusion: Characteristics of strains of toxoplasms isolated from material of brain section of patients with HIV infection were studied. Their low virulence and ability to prolonged persistence in organism of mice were demonstrated on in vivo model. Possible association of T. gondii strains' virulence and clinical symptoms with pathogen's genetic polymorphism and its clonal population structure was discussed.

Aim: To detect clinical characteristics of cerebral toxoplasmosis in HIV-infected patients, to clarify diagnostic role of detection of DNA and antibodies to Toxoplasma gondii in the cerebrospinal fluid (CSF) and blood., Material and Methods: Diagnostic procedures were performed in 156 patients with HIV infection at the stage IVB (AIDS) in 2003-2006. All the patients suffered from diseases of the central nervous system (CNS). Toxoplasmosis was diagnosed in 57 (36%) cases. Lumbar puncture, MR imaging of the brain, reaction of indirect immunofluorescence, polymerase chain reaction and enzyme immunoassay were made to identify IgM and IgG to T. gondii., Results: Typical for HIV-infected patients with cerebral toxoplasmosis were focal symptoms of CNS affection, hemipareses, adynamia, mental disorders, intoxication symptoms., Conclusion: MR imaging data are very important. Toxoplastosis is characterized by multiple destructive foci in the hemispheres and cerebellum with great amount of the parasites along the periphery of brain tissue necrosis. Detection of the infective agent DNA and specific IgG antibodies in cerebrospinal fluid confirms the presence of toxoplasmosis but sensitivity of the markers is low. IgG antibodies to T. gondii have diagnostic implications if they occur in high and moderate titers.

Aim: To study clinical and morphological characteristics of gastrointestinal cytomegalovirus (CMV) infection in HIV-infected subjects., Material and Methods: The examination of 70 HIV-infected subjects (all of them had secondary diseases, AIDS, CMV infection in the gastrointestinal tract; mean age 31.2 +/- 1.4 years) observed from 1993-2005 included conduction of flow cytofluorimetry (to assess immunity), esophagogastroduodenoscopy, colonoscopy, PCR (to assay CMV DNA in blood leukocytes), examination of biopsy and autopsy samples for CMV DNA and other pathogens of opportunistic diseases). There were 55 lethal outcomes. In autopsy, a total macroscopic and microscopic examination of the gastrointestinal tract was made. Serial histotopographic sections were studied with a wide spectrum of histological stains., Results: CMV gastrointestinal lesion was diagnosed in 38.9% of 180 HIV-infected subjects who had stomatitis, pharyngitis, esophagitis, gastritis, enteritis, enterocolitis or colitis. Diagnostic criteria of viral lesion were high blood concentrations of CMV DNA, the presence of cytomegalocells, CMV DNA in biopsy or autopsy material., Conclusion: CMV infection manifested with severe pain, loss of weight, weakness, remitting fever. Gastrointestinal lesions were erosive-ulcerous or ulceronecrotic. The following pathogenetic chain of CMV infection course in the gastrointestinal tract was established: vasculitis--microcirculatory disorders--segmental ischemia--necrosis with inflammatory infiltration and CMV transformation of the cells--fibrosing--cicatricial transformation of the organ wall. Developing sclerosis due to CMV involvement of the intestine may promote cancer, but this should be proved in further studies. CMV gastrointestinal infection was successfully treated by cimeven (ganciclovir) and valcit (valganciclovir). The effect was achieved in 91% cases.