Vol 62, No 2 (2017)

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by a new virus (SFTS virus) reported to be endemic to central and northeastern parts of China. SFTS virus, which is classified into the genus Phlebovirus (the Bunyaviridae family), is suspected to be a tick-borne virus owing to evidence in two species of ticks: Haemaphysalis longicornis and Rhipicephalus microplus. SFTS virus is detected among many species of domestic animals in China. The clinical symptoms of SFTS include fever, thrombocytopenia, leucocytopenia, gastrointestinal symptoms, neural symptoms, bleeding tendency. The fatality rate of SFTS is 6-30%. Person-to-person transmission of SFTS virus is possible through blood contact. Clinical and epidemiological studies of SFTS, the cases of SFTS outside China, person-to-person transmission of SFTS virus, evolutionary and molecular analysis of the emergent SFTS virus, and risk assessment of human infection with a novel phlebovirus are considered in this review.

About 3,000 cases of TBE are registered annually in the Russian Federation. Vaccination is the main way to prevent the tick-borne encephalitis disease. Comparative study of the reactogenicity and immunogenicity of a new vaccine «Tick-E-Vac» was held. Volunteers aged from 16 years old were twice immunized with the vaccines «Tick-E-Vac» or «Encevir» derived from strains of Far East subtype of TBE virus, according to standard and emergency schemes. The clinical study was randomized, comparative, blind, and controlled. The frequency, intensity, time of occurrence, and duration of local and general reactions had been recorded. The titers of antiviral antibodies in ELISA had been determined to assess the immunological efficacy of vaccination. According to the results of the clinical study, the severity of local and general reactions in initial seronegative recipients was weak or moderate. The symptoms were usually manifested within 1-2 days after injection and persisted for not more than 4 days, after which time the symptoms disappeared. There was no statistically significant difference in the reactogenicity of the vaccines after the first and after the second injection. The reactogenicity also did not depend on the gender of recipients. After the first immunization, the level of seroprotection was not less than 43%; the average geometric titer of antibodies (GTA), not less than 1:200. After the second injection, the level of seroprotection reached 90-100%; GTA, not less than 1:500. The data on the reactogenicity and immunogenicity to the original seropositive recipients is not significantly different from the data for the initial seronegative recipients. The data indicate weak reactogenicity of the vaccines «Tick-E-Vac» and «Encevir». Double vaccination with an interval of 14 or 30 days leads to the formation of expressed immune response. Thus, differences in the level of seroprotection and in antiviral titers in the cases of the standard and emergency vaccination schedules are not statistically significant. The correlation between the development in recipients of local and general symptoms and the immunological efficacy of the vaccines has not been identified.

We have developed a multiplex immunoassay test (immunochip) based on PHOSPHAN technology for the detection of immunoglobulin G to herpes simplex virus (HSV) types 1, 2 and cytomegalovirus (CMV). The immunochip consists of HSV type specific gG1 (HSV-1) and gG2 (HSV-2) recombinant antigens, the lysate antigen for detection of total IgG to both HSV types (HSV 1/2), and CMV specific chimeric recombinant antigen containing the immunodominant sequences of pp150, gB, pp28 and pp52 proteins. The sensitivity and specificity of simultaneous IgGs detection with recombinant proteins were comparable to the commercial ELISA kits regardless of the kind of investigated serum specimens (patient sera, standard serum panels). The lysate HSV antigen was as sensitive but significantly less specific, so that it could not be recommended for use as a component of the multiplex test. These results can be used as a basis for creating commercial multiplex tests intended for high-productive screening of HSV, CMV and other TORCH-infections in a clinical laboratory.