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Soluble human leukocyte antigen G (sHLA-G) plays a key role in pregnancy through interaction with decidual natural killer (dNK) cell inhibitory receptors at the maternal-fetal interface. To demonstrate the possible role of sHLA-G during the pregnancy with Toxoplasma gondii infection, we compared the concentration of a murine functional homolog of sHLA-G, Qa-2, in T. gondii infected and non-infected pregnant C57BL/6 mice, and that of sHLA-G in BeWo culture supernatant. In addition, the levels of KIR2DL4 expressed on human dNK cells and NKG2A in pregnant mice were evaluated. We showed that T. gondii infection result in significant increase in the level of Qa-2 and NKG2A in pregnant mice. sHLA-G and KIR2DL4 in human samples were also significantly upregulated under the condition of T. gondii infection. The further treatment with sHLA-G antibody could reduce the expression level of KIR2DL4 which was upregulated by T. gondii infection. In summary, sHLA-G could upregulate the expression level of KIR2DL4 which lead to excessive immunological tolerance, and further contributed to T. gondii immunity escaping and affecting fetus via vertical transmission which may lead to adverse outcomes.

The serological survey of humans, as well as agricultural animals and rodents, for the presence of zoonotic infections, was carried out. Local inhabitants were shown to have contacts with the causative agents of pseudotuberculosis, enteric yersiniosis, tularemia, leptospirosis, Q fever, tick-borne rickettsiosis, chlamydiosis, toxoplasmosis. The immune stratum with respect to enteric yersiniosis was found to have a greater index, while the immune strata with respect to chlamydiosis, Q fever, pseudotuberculosis had the least indices. However, the indices of immune strata perceptibly varied in individual regions. The highest occurrence of antibodies to all above-mentioned zoonotic infections was registered in Megino-Kangalasskiĭ, Amga and Neriungrinskiĭ ulusy [correction of regions]. The probable sources of leptospirosis, toxoplasmosis and Q fever were agricultural animals, while the probable sources of enteric yersiniosis and leptospirosis were rodents.

Enzyme immunoassay was used in screening for toxoplasmosis of 500 residents of the town of Ghulistan and of 1074 residents of the town of Shavat in the Khorezm district of Uzbekistan. All the examinees were aged 15 to 40. The share of seropositive subjects in Ghulistan was 24.6%, that in Shavat 14.6%, the toxoplasmosis loimopotentials were 0.87 and 0.62%, respectively. The predicted parameters were as follows: new cases of toxoplasmosis among pregnant women were 4.9% in Ghulistan and 3.9% in Shavat, the incidence of congenital condition 1.7 and 1.3%, respectively, the incidence of manifest congenital toxoplasmosis 0.6 and 0.4%, respectively. The presence of a cat in the house was associated with higher share of seropositive subjects in the town of Shavat as against Ghulistan. An urban focus (Ghulistan) appeared more intensive as against a rural type focus (Shavat) at the expense of a higher intensity of the xenotropic route of the agent transmission.

A total of 2643 persons in 5 different regions were examined for toxoplasmosis by the immunofluorescence test and toxoplasmin skin test. The presence in the house of cats and dogs was taken into account. In two of the five regions under study there was revealed an increased incidence of toxoplasmosis in persons keeping cats; this confirmed the role of these animals as a source of toxoplasmosis infection. The absence of such increase in the incidence of the disease in other regions in explained by the character of buildings admitting migration of cats or the presence in the given region of other active sources of infection. Toxoplasmosis incidence in persons who kept or didn't keep dogs displayed no significant difference.

The possibility of using the primary epidemiological unit, force of infection, as a criterion for evaluating the intensity of the transfer of toxoplasmosis among the population at the focus of infection has been established. The comparison of data obtained in different regions indicates that the level of the force of infection is, in general, low, but it can vary within a wide range. The problem of the suitability of using the force of infection as a criterion for dividing territories into zones with respect to toxoplasmosis is discussed.

Prophylaxis of toxoplasmosis consists of a complex of general medical and veterinary measures. Of importance is detection of latent forms of toxoplasmosis in pregnant women and their timely treatment. Thorough clinical and immunological examination of persons with prolonged diseases of obscure etiology is necessary. Suggestions are given for dispensary observation of persons who sustained the disease and had positive immunological reactions for toxoplasmosis. Materials on prophylaxis of hemotransfusion transmission of the infection are presented for the first time. A number of recommendations concerns measures of general organization and also planned prophylactic examination with the use of immunological methods of some groups of population with increased risk of infection.