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Experiments on mice demonstrated the ability of 3 flaviviruses and 1 bunyavirus to suppress the activity of the effectors of the graft-versus-host (GVH) reaction. The conditions of the suppression of the primary immunological recognition were shown to differ in infections caused by different viruses. In experimental flavivirus infections caused by Langat, dengue 2 or yellow fever (strain 17D) viruses T-suppressor cells were activated, and their activity was realized only in respect to syngeneic or semisyngeneic target cells. In mice infected with Tahyna virus (a bunyavirus) no suppressor cells capable of suppressing the activity of the effectors of the GVH reaction were detected. The suppression of this reaction, not linked with the activity of the detected T-suppressor cells, was observed in the Langat virus infection under conditions of bilateral incompatibility when both the donor and the recipient were infected.

The successful application of the immunoperoxidase method of (IP) with light microscopy for rapid detection of certain togaviruses and orthopoxviruses and antibodies to them is described. A comparative evaluation of the IP and immunofluorescent (IF) method for these purposes was performed. The results indicate practically similar sensitivity and specificity of both methods. The detection of viral antigen directly depended upon the infective dose and time of examinations (within 4--12 hours postinoculation). In evaluating the IP method, however, the account should be taken of the fact that it does not require expensive equipment and therefore may be used in any practical laboratory or even under field conditions. Rapid detection of both viral antigens and antiviral antibody by this method opens approaches for its wide application in the future.

In August-September 1981, in some areas of Karelia (on the border of northern and middle taiga) there occurred diseases with signs of fever, rash, and arthralgia developing in some patients into a chronic condition. Examinations of paired sera from patients with the acute disease and from convalescents using a set of Toga- and Bunya-viruses showed the etiology of the disease to be associated with a virus from the Togaviridae family, genus Alphavirus, of the antigenic Sindbis complex.