[Results of investigation of ticks in Volga river delta (Astrakhan region, 2017) for Crimean-Congo hemorrhagic fever virus (Nairoviridae, Orthonairovirus, CCHFV) and other tick-borne arboviruses.]

INTRODUCTION: There are natural foci of Crimean-Congo hemorrhagic fever (CCHF) that vectored by Hyalomma marginatum ticks in Volga river delta (Astrakhan region, South of Russia). The circulation of Dhori virus (DHOV) (Thogotovirus: Orthomyxoviridae) has been also shown here. We hypothesized that other tick-borne arboviruses are also likely to circulate in the region. In particular, Bhanja virus (Phlebovirus: Phenuiviridae), Wad Medani virus (Orbivirus: Reoviridae), and Tamdy virus (Orthonairovirus: Nairoviridae), which were found to circulate in neighboring regions and are vectored by Haemaphysalis spp., Dermacenter spp., and Hyalomma spp. ticks. OBJECTIVES: The aim of the study was to examine ixodid ticks in Volga river delta for the presence of CCHFV, DHOV, Bhanja virus, Wad Medani virus, and Tamdy virus. MATERIAL AND METHODS: Ticks were collected in Volga river delta in 2017. We used molecular genetic methods for the detection and analysis of nucleic acids (PCR, sequencing, phylogenetic analysis). RESULTS: We detect CCHFV and DHOV RNA in H. marginatum ticks. The rate of infected H. marginatum ticks was 1.98% for CCHFV and 0.4% for DHOV. The results of genetic analysis showed that found DHOV strains are almost identical (99-100% in the M gene) and forms a separate genetic lineage alongside of Batken virus from Central Asia. At the same time, Bhanja virus, Wad Medani virus, and Tamdy virus were not found in ticks, collected in this region. CONCLUSIONS: DHOV is circulating in the natural foci of CCHF in the Volga river delta. The ratio of infection of H. marginatum with CCHFV and DHOV was determined for the first time.

[Molecular genetic analysis of Tahyna virus strains].

The partial nucleotide sequence of S and M genome segments was identified in 13 little studied Tahyna virus (Bunyaviriridae, Bunyavirus, California encephalitis serogroup) strains isolated in Czechoslovakia, Finland, Armenia, Azerbaijan, Kazakhstan, and Tajikistan. A phylogenetic analysis indicated that the examined strains form two groups with a geographical connection: European and Asian genetic groups.

[Detection of rubella virus RNA in clinical material by real time polymerase chain reaction method].

AIM: Development of a reagent kit for detection of rubella virus RNA in clinical material by PCR-RT. MATERIALS AND METHODS: During development and determination of analytical specificity and sensitivity DNA and RNA of 33 different microorganisms including 4 rubella strains were used. Comparison of analytical sensitivity of virological and molecular-biological methods was performed by using rubella virus strains Wistar RA 27/3, M-33, "Orlov", Judith. Evaluation of diagnostic informativity of rubella virus RNAisolation in various clinical material by PCR-RT method was performed in comparison with determination of virus specific serum antibodies by enzyme immunoassay. RESULTS: A reagent kit for the detection of rubella virus RNA in clinical material by PCR-RT was developed. Analytical specificity was 100%, analytical sensitivity - 400 virus RNA copies per ml. Analytical sensitivity of the developed technique exceeds analytical sensitivity of the Vero E6 cell culture infection method in studies of rubella virus strains Wistar RA 27/3 and "Orlov" by 11g and 31g, and for M-33 and Judith strains is analogous. Diagnostic specificity is 100%. Diagnostic specificity for testing samples obtained within 5 days of rash onset: for peripheral blood sera - 20.9%, saliva - 92.5%, nasopharyngeal swabs - 70.1%, saliva and nasopharyngeal swabs - 97%. Positive and negative predictive values of the results were shown depending on the type of clinical material tested. CONCLUSION: Application of reagent kit will allow to increase rubella diagnostics effectiveness at the early stages of infectious process development, timely and qualitatively perform differential diagnostics of exanthema diseases, support tactics of anti-epidemic regime.

[Use of RT-PCR and enzyme immunoassays for the specific diagnosis of Crimean hemorrhagic fever].

The objective of the investigation was to evaluate the efficiency of the RT-PCR kit "AmplySens CHF" produced by InterlabService of the Central Research Institute of Epidemiology and that of the ELISA kits made by the D. I. Ivanovsky Research Institute of Virology for the specific diagnosis of Crimean hemorrhagic fever (CHF). Examination of sera from CHF patients from the Astrakhan Region showed that positive RT-PCR results were observed in 95.2 and 37.5% on days 4-8 and 9-13 after disease onset, respectively; but they were absent on days 13-17. Positive ELISA-IgM results were found in 93% on disease days 6 to 16. A high percentage (78.9%) of positive IgG samples was seen only on days 9-16. Thus, RT-PCR has a marked efficiency in diagnosing CHF until day 8 of illness while ELISA-IgM has it on day 8 or later. ELISA-IgG can be considered to be a confirming rather than compulsory test. The findings suggest that the RT-PCR kit "AmplySens CHF" produced by InterlabService of the Central Research Institute of Epidemiology and that of the ELISA kits made by the D. I. Ivanovsky Research Institute of Virology have a pronounced sensitivity and specificity and a high efficiency when concurrently used to verify CHF in patients.

[A case of Crimean-Congo hemorrhagic fever in the Anapa District, Krasnodar Territory].

The paper gives information on the first case of Crimean-Congo hemorrhagic fever detected in a female resident of the Anapa District, Krasnodar Territory, in 2005 in the past 57 years.

[PHOSPHAN microplate technology-based microarray for the determination of IgG antibodies against West Nile and Crimean-Congo hemorrhagic fever viruses].

The paper demonstrates it possible to work out a phosphorescence analysis (PHOSPHAN) microplate technology-based microarray for concurrently examining human sera and detection of their specific IgG antibodies against two heterological West Nile and Crimean-Congo hemorrhagic fever viruses. The sensitivity and specificity of the microarray were comparable with those of enzyme immunoassay with separate sample testing. The advantages of PHOSPHAN were associated with the microplate format of an immunoassay and its enhanced multiplexity, which may contribute to the lower cost of clinical sample testing.

[Molecular-genetic analysis of the Batai virus strains isolated from mosquitoes in Volgograd Region of the Russian Federation, West Ukraine, and Czech Republic].

Partial nucleotide sequence of the M-segment from five Batai virus strains was determined. These strains were isolated in Volgograd Region, West Ukraine, and Czech Republic. Our data based on the partial sequence of the M-segment of Batai virus strains demonstrated that the strains isolated in Russian Federation, Ukraine, and Czech Republic grouped together into an European genetic group that was distinct from Asian and African strains of Batai virus.

[Results of examination of healthy residents in the southern region of Russia and patients feverish to pappataci fever virus antibodies].

Sera from patients with acute seasonal fevers and apparently healthy individuals living in the Astrakhan Region, Krasnodar Territory, or Rostov Region were examined in two modifications of enzyme immunoassay for detection of IgM and IgG antibodies to Neapolitan and Sicilian pappataci fever viruses. IgM antibodies to Sicilian pappataci fever virus were detected in a patient from the Volodarsky District, Astrakhan Region, who had been admitted for the unverified diagnosis of Q fever. A donor residing in the Novorossiysk District, Krasnodar Territory, was found to have IgA antibodies to Neapolitan pappataci fever virus. The findings show it expedient to conduct further investigations of the serodiagnosis and seroepidemiology of pappataci fevers in the southern Russian region where mosquitoes of the genus Phlebotomus inhabit.

[Phylogenetic analysis of complete nucleotide sequence of a snowshoe hare (Lepus americanus) virus genome].

The complete nucleotide consequence of snowshoe hare (Lepus americanus) virus (SSHV) genome was first determined. Phylogenetic analysis indicated the identity of the study strain in the complete S segment and an L-segment with a length of 145 amino acid residues with SSHV sequences from the database GenBank (J02390, AF393325). The homology of an M segment of the study segment was 99.7% with the consequences of the same from the database GenBank (K02539). La Crosse virus is most genetically close to SHV among the representatives of the California encephalitis serocomplex.

[In vitro activity of Russian ribavirin on the models of Crimean-Congo hemorrhagic fever virus, Rift Valley fever virus, and Tahyna and Dhori viruses].

The high activity of ribavirin made by effective biotechnology in Russia was established in in vitro experiments using the models Crimean-Congo hemorrhagic fever virus, Rift Valley fever virus, and Tahyna and Dhori viruses, which suggests that it is promising in using the drug in the treatment of infection with these viruses.

[ELISA and PCR test systems used to detect Crimean-Congo hemorrhagic fever virus].

Studying the sensitivity and specificity of enzyme-linked immunosorbent assay (ELISA) for the indication of Crimean-Congo hemorrhagic fever (CCHF) virus antigens and those of reverse transcription and polymerase chain reaction (RT-PCR) for the detection of CCHF virus RNA, and those of a intercerebral infection method in newborn albino mice systems for the determination of viral infectious activity established that the sensitivity of ELISA was 1-2 orders of magnitude less than that of RP-PCR. The latter proved to be better in studying the sera sampled from patients with CCHF. The results of studying the samples of H. marginatum ticks, the CCHF virus vectors by ELISA and RT-PCR were similar.

[Astrocytic morphological responses in different murine brain regions in the simulation of West Nile fever].

The brains from the mice infected intraperitoneally (with development of these or those symptoms of viral encephalitis) or intramuscularly with the Astrakhan West Nile fever virus strain (AcT 986) was pathomorphologically studied. Clinicomorphological changes in the neurons and vessels of the microcirculatory bed were found in the dorsal regions of medulla oblongata. Immunohistochemicall analysis showed that mature and/or activated astrocytes increased in number, largely in the animals without clinical manifestations of encephalitis. The findings provide evidence that cerebral astrocytes play a protective and adaptive role that seems to depend on the biological properties of the pathogen.

[Morphological and immunohistochemical changes in tissues of the lung, myocardium and kidney in experimental West Nile fever].

An experimental infection of mice with West Nile virus (WNV) showed pronounced dystrophic changes in tissues of the kidneys and myocardium as well as expression of WNV antigens in cells of the lungs, kidneys and myocardium, which can denote tropism of WNV to tissues of the lungs, kidneys and myocardium.

[Hepatotropic action of the virus of West Nile fever].

An experimental infection of mice with West Nile Virus (WNFV) showed pronounced dystrophic changes in the hepatic parenchyma and expression of WNV antigens in the endothelium of hepatic capillaries and in hepatocyte cytoplasm, which testifies to the tropic action of WNFV to hepatic tissue.

Tick-borne virus diseases of human interest in Europe.

Several human diseases in Europe are caused by viruses transmitted by tick bite. These viruses belong to the genus Flavivirus, and include tick-borne encephalitis virus, Omsk haemorrhagic fever virus, louping ill virus, Powassan virus, Nairovirus (Crimean-Congo haemorrhagic fever virus) and Coltivirus (Eyach virus). All of these viruses cause more or less severe neurological diseases, and some are also responsible for haemorrhagic fever. The epidemiology, clinical picture and methods for diagnosis are detailed in this review. Most of these viral pathogens are classified as Biosafety Level 3 or 4 agents, and therefore some of them have been classified in Categories A-C of potential bioterrorism agents by the Centers for Disease Control and Prevention. Their ability to cause severe disease in man means that these viruses, as well as any clinical samples suspected of containing them, must be handled with specific and stringent precautions.

[Pathomorphology of West Nile fever]. / Patomorfologiia likhoradki zapadnogo Nila.

8 patients, aged from 61 to 70 years, died from serous meningoencephalitis during the outburst of the West Nile fever in Volgograd in 1999-2001, were studied morphologically. Serous meningoencephalitis with necrotic vasculitis is a characteristic feature of this fever with degenerative changes and destructive foci in the brain. Proteinic and fatty inflammatory and lymphomacrophageal reactions were observed in the liver, serous productive myocarditis and cardiomyocytic necrosis dystrophy. Desquamative pneumonia, intracapillary nephritis were also seen. Immunohistochemical reaction against virus of this fever was positive in the vascular endothelium of parenchymal organs, hepatocytes, neurons of the brain.