Russian Spring-summer Encephalitis Virus Research Articles

Comparative analysis of immune responses to Russian spring–summer encephalitis and Omsk hemorrhagic fever viruses in mouse models

Omsk hemorrhagic fever virus (OHFV) and Russian spring–summer encephalitis virus (RSSEV) are tick-borne flaviviruses that have close homology but different pathology and disease outcomes. Previously, we reported that C57BL/6 and BALB/c mice were excellent models to study the pathology and clinical signs of human RSSEV and OHFV infection. In the study described here, we found that RSSEV infection induced robust release of proinflammatory cytokines (IL-1α, IL-1β, IL-6 and TNF-α) and chemokines (MCP-1, MIP-1β, RANTES and KC) in the brain at 9 and 11dpi, together with moderate to low Th1 and Th2 cytokines. In contrast, OHFV infection stimulated an early and prominent induction of IL-1α, TNF-α, IL-12p70, MCP-1, MIP-1α and MIP-1β in the spleen of infected mice. Collectively our data suggest that a differential host response to infection may lead to the alternate disease outcomes seen following OHFV or RSSEV infection.

Clinical evaluation of highly pathogenic tick‐borne flavivirus infection in the mouse model

The objective of this study was to evaluate the feasibility of using clinical parameters to demonstrate disease progression and differentiate between Omsk hemorrhagic fever virus (OHFV) and Russian spring-summer encephalitis virus (RSSEV) infection in the mouse model. Adult C57BL/6 and balb/c mice were infected with either OHFV or RSSEV by footpad inoculation and their temperature, body weight, clinical signs complete blood count, and blood chemistries were evaluated for up to 15 days post-infection (dpi). Clinical evaluation showed that OHFV infection seriously affects balb/c mice, which had shorter average survival times (ASTs) than other groups. On the contrary, RSSEV infection of C57BL/6 mice was more severe than in balb/c mice. During these studies, the development of fever was not observed and the body weight of OHFV infected balb/c and C57BL/6 mice began to decline sharply starting from day 7 and 8, respectively, which correlated with disease onset. Peak increase of globulin and neutrophils was demonstrated after 9 dpi in OHFV infected mice; however, the lymphocyte number was not affected. Viremia was undetectable in these animals with either virus infection, but virus was found in most organs tested. These results indicate marked differences in the clinical signs, pathology, and immune response of mice infected with either OHFV or RSSEV and further validate the use of this mouse model system to evaluate human disease.

Host response to Tick-bone encephalitis and Omsk hemorrhagic fever (129.22)

Abstract Omsk hemorrhagic fever virus (OHFV) and Russian spring-summer encephalitis virus (RSSEV) are tick-borne flaviviruses of the genus Flavivirus, Family Flaviviridae. Although OHFV and RSSEV have 90% homology at their amino acid level, they have different disease outcomes. OHFV infection mainly causes hemorrhagic fever, however RSSEV infection results in a severe form of CNS disorder. Understanding of the pathogenesis of tick-borne encephalitis and hemorrhagic fever is of major importance due to significant public health problem and the lack of treatment. Dendritic cells (DC) play a critical role for both innate and adaptive immune responses. DC function as the best antigen presenting cells to T-cells by upregulating expression of costimulatory and MHC molecules, and cytokine production. In these experiments we examined interactions between OHFV/RSSEV and murine DC to identify responses that contribute to the pathogenesis of tick-borne flaviviruses. The DC surface markers were analyzed using flow cytometry, and cytokines and chemokines were quantified by Bioplex assay. OHFV/RSSEV infection of DC resulted in the secretion of a broad array of cytokines and chemokines. OHFV/RSSEV exposure did not activate DC maturation markers as compared to LPS stimulated DC. Infected DC had similar levels of CD80 and CD86 expression relative to the mock infected DC. Our data demonstrate that the functional maturation of DC in response to OHFV/RSSEV infection is modified leading to a reduction of the capacity of DC antigen presentation and consequently T-cell activation. This research was supported by the Western Regional Center of Excellence (U54AI056157)

Evaluation of Tick-Borne Encephalitis DNA Vaccines in Monkeys

Tick-borne encephalitis is usually caused by infection with one of two flaviviruses: Russian spring summer encephalitis virus (RSSEV) or Central European encephalitis virus (CEEV). We previously demonstrated that gene gun inoculation of mice with naked DNA vaccines expressing the prM and E genes of these viruses resulted in long-lived homologous and heterologous protective immunity (Schmaljohn et al., 1997). To further evaluate these vaccines, we inoculated rhesus macaques by gene gun with the RSSEV or CEEV vaccines or with both DNA vaccines and compared resulting antibody titers with those obtained by vaccination with a commercial, formalin-inactivated vaccine administered at the human dose. Vaccinations were given at days 0, 30, and 70. All of the vaccines elicited antibodies detected by ELISA and by plaque-reduction neutralization tests. The neutralizing antibody responses persisted for at least 15 weeks after the final vaccination. Because monkeys are not uniformly susceptible to tick-borne encephalitis, the protective properties of the vaccines were assessed by passive transfer of monkey sera to mice and subsequent challenge of the mice with RSSEV or CEEV. One hour after transfer, mice that received 50 μl of sera from monkeys vaccinated with both DNA vaccines had circulating neutralizing antibody levels <20–80. All of these mice were protected from challenge with RSSEV or CEEV. Mice that received 10 μl of sera from monkeys vaccinated with the individual DNA vaccines, both DNA vaccines, or a commercial vaccine were partially to completely protected from RSSEV or CEEV challenge. These data suggest that DNA vaccines may offer protective immunity to primates similar to that obtained with a commercial inactivated-virus vaccine.

Epidemiology of tick-borne encephalitis in Japan

A tick-borne encephalitis (TBE) patient has not been reported for many years in Japan although a serological survey of domestic animal sera suggested the presence of TBE foci in Hokkaido, the northern island of Japan. In October 1993 in Hokkaido, a severe encephalitis case in a farm wife was diagnosed as tick-borne encephalitis. Serological examination of paired sera showed a rise of neutralization (NT) antibody titer to Russian spring summer encephalitis virus. A sero-epizootiological survey of dogs showed that the TBE-related virus was prevalent in the area. Three virus isolates were obtained from the blood of sentinel dogs and the antigenic analysis grouped the isolates into TBE-related viruses. Sequence analysis of envelope protein gene identified one of the isolates as the same subtype as Russian spring summer encephalitis (Far-Eastern TBE) virus. The results provide the evidence that TBE is endemic in a certain area of Japan.

Naked DNA vaccines expressing the prM and E genes of Russian spring summer encephalitis virus and Central European encephalitis virus protect mice from homologous and heterologous challenge.

Naked DNA vaccines expressing the prM and E genes of two tick-borne flaviviruses, Russian spring summer encephalitis (RSSE) virus and Central European encephalitis (CEE) virus were evaluated in mice. The vaccines were administered by particle bombardment of DNA-coated gold beads by Accell gene gun inoculation. Two immunizations of 0.5 to 1 microg of RSSE or CEE constructs/dose, delivered at 4-week intervals, elicited cross-reactive antibodies detectable by enzyme-linked immunosorbent assay and high-titer neutralizing antibodies to CEE virus. Cross-challenge experiments demonstrated that either vaccine induced protective immunity to homologous or heterologous RSSE or CEE virus challenge. The absence of antibody titer increases after challenge and the presence of antibodies to E and prM, but not NS1, both before and after challenge suggest that the vaccines prevented productive replication of the challenge virus. One vaccination with 0.5 microg of CEE virus DNA provided protective immunity for at least 2 months, and two vaccinations protected mice from challenge with CEE virus for at least 6 months.

Infection of Macaca radiata with viruses of the tick-borne encephalitis group

Our studies confirmed the susceptibility of Macaca radiata (bonnet macaques) to Kyasanur Forest disease (KFD) and enabled us to demonstrate KFD virus-specific gastrointestinal and lymphoid lesions. Significant histopathological changes occurred in the small and large intestine, spleen and lymph nodes; and viral antigens were found in these same organs by immunohistochemistry. Viral antigen-positive cells were always associated with histological evidence of necrosis, which suggests that cell death occurred directly from viral replication or secondarily from attack by immune mechanisms. In contrast, M. radiata infected with Omsk virus did not show any signs of clinical disease, and no virus could be isolated from tissues or blood at the end of the experiment. However, M. radiata infected with Russian spring-summer encephalitis (RSSE) developed clinical signs in the central nervous system; and, in one monkey, RSSE virus was isolated from the brain, and viral antigen was localized in neurons. Our data indicate that M. radiata is an excellent model to study human disease caused by KFD virus and could serve as a model for human disease caused by other, related strains of this group of viruses.

Sequential immunization procedure against Group B arboviruses using living attenuated 17D yellow fever virus, living attenuated Langat E5 virus, and living attenuated dengue 2 virus (New Guinea C isolate).

Spider monkeys immunized sequentially with living 17D yellow fever virus, living attenuated Langat E5 virus, and living attenuated dengue 2 virus (New Guinea C isolate) responded with high hemagglutinating-inhibition antibody titers against 21 Group B arbovirus antigens that were tested. Such monkeys also responded with neutralizing antibodies against 20 Group B arboviruses that were tested. These vaccinated monkeys were protected against subcutaneous challenges with dengue serotypes 1, 2, 3 or 4, Russian spring-summer encephalitis virus, Kyasanur Forest Disease virus, Omsk hemorrhagic fever virus, Japanese encephalitis virus, Murray Valley encephalitis virus, West Nile virus, and Kadam virus. The protection against these viruses was based on a much lower viremia, or absence of histologic lesions in the central nervous system, or absence of an antibody booster response. The 3-virus sequential immunized spider monkeys were also protected against Modoc virus as determined by viremia studies, in spite of the fact that no detectable serum neutralizing antibodies were found in these animals at the time of challenge. The development of the sequential immunization procedure is discussed.

Ixodes hyatti, n. sp., and I. shahi, n. sp. (Acarina: Ixodidae), parasites of Pikas (Lagomorpha: Ochotonidae) in the Himalayas of Nepal and West Pakistan.

Ixodes (Ixodes) hyatti, n. sp., is closely related to I. (I.) persulcatus Schulze, the Siberian taiga vector of Russian spring-summer encephalitis virus, and is tentatively associated with a new arbovirus recently recorded by University of Maryland School of Medicine virologists. This new species is recorded from Ochotona roylei subspp. between 2735 and 4615 m altitude in the Himalayas of Nepal and West Pakistan. Nymphs and mating adults were taken on pikas in severe winter weather, and females, nymphs, and larvae in early and late monsoon and postmonsoon periods. I. shahi, n. sp. (subgenus uncertain), is related to I. acutitarsus (Karsch), which commonly parasitizes humans in the Himalayas. This new species is recorded from O. r. roylei (Ogilby) and Mus musculus subsp. between 3000 and 3845 m altitude in Nepal. Pikas were infested by females, nymphs, and larvae in premonsoon periods and by nymphs and larvae in late monsoon and postmonsoon periods. A larva was taken from a mouse in late winter.

GROWTH OF RUSSIAN SPRING SUMMER ENCEPHALITIS (RSSE) VIRUS IN MONOLAYER CELL CULTURES OF PORCINE KIDNEY, BOVINE EMBRYO KIDNEY AND CHICKEN EMBRYO.

The Parker strain of Russian spring-summer encephalitis virus was maintained by serial passage in cell cultures of pig kidney, bovine embryo kidney and chick embryo. In pig kidney cell culture the virus proliferated and produced cytopathic changes. Bovine embryo kidney cell culture supported the proliferation of the virus but no cytopathic effect was produced. In chick embryo cell culture cytopathic changes, which were not shown in the early stages of passage, appeared after several passages. The virus adapted to this host system produced more acids in this culture under certain conditions. The virus interfered with Newcastle disease virus in cell cultures of swine kidney and bovine embryo kidney but not in chick embryo cell culture. The cytopathogenesis in chick embryo or pig kidney cell culture, the interference phenomenon with Newcastle disease virus in bovine embryo or pig kidney cell culture and the pH change in chick embryo cell culture could be employed as criteria for detecting and measuring the virus and its neutralizing antibody.

EXPERIMENTAL TRANSOVARIAL TRANSMISSION OF KYASANUR FOREST DISEASE VIRUS IN HAEMAPHYSALIS SPINIGERA.

TRANSOVAJRIAJL passage in ticks has been investigated for several viruses of the tick-borne encephalitis complex. Russian workers have reported that Russian spring–summer encephalitis virus can pass transovarially in Ixodes persulcatus, I. ricinus, Dermacentor silvarum and Haemaphysalis concinna1. Benda2, working with Ixodes ricinus and the European strain of tick-borne encephalitis in Czechoslovakia, demonstrated transovarial transmission in only 6 per cent of ticks, while Smorodintsev3 in the U.S.S.R. reported that it occurred in 5–25 per cent of ticks. In an investigation confirming transovarial transmission of tick-borne encephalitis virus in I. ricinus, Rehacek4 found that it occurred in 2 per cent of ticks infected by feeding and in 20 per cent of ticks infected by inoculation after feeding. Laboratory studies with a third member of the complex, Kyasanur forest disease virus, and its vector Haemaphysalis spinigera are reported here.

ウシ胎児腎臓組織培養におけるロシヤ春夏脳炎ウイルスのニユーカッスル病ウイルスにたいする干渉

The virus of Russian spring summer encephalitis (RSSE) multiplied without any cytopathogenic effect (CPE) in cell culture of bovine embryonic kidney. Newcastle disease (ND) virus proliferated with CPE in this cell culture, but was not able to proliferate and produce CPE in cell culture previously infected with RSSE virus. With small doses of RSSE virus it took about 4 days for the majority of cells in culture to acquire the ability to interfere with ND virus. Interfering activity of RSSE virus could be detected earlier with a smaller inoculum of ND virus than with a larger one, but the inoculum size of ND virus did not affected the result when ND virus was given at a certain interval following RSSE virus inoculation or later.Interference between these two viruses were observed in renal cell cultures of the swine, cat, rabbit, and guinea pig, and not in cell cultures of hamster and chicken kidneys or chick embryo tissues. RSSE virus interfered with fowl plague virus and almost or entirely not with viruses of vaccinia, herpes, equine abortion, Venesuelan equine encephalitis, and bovine infectious rhinotracheitis, and HVJ (hemagglutinating virus of Japan).Japanese encephalitis virus and Negishi virus also interfered with ND virus in bovine embryonic renal cell culture.Interference of RSSE virus with ND virus was specifically neutralized by immune serum to RSSE virus.Based on these findings a procedure was established for detecting and measuring RSSE virus and its neutralizing antibody.

A virus resembling Russian spring-summer encephalitis virus from an ixodid tick in Malaya.

A virus resembling Russian spring-summer encephalitis virus from an ixodid tick in Malaya.

Neutralizing Antibodies Against Certain Viruses in the Sera of Residents of India

Summary Blood samples obtained from indigenous residents of 38 localities in 6 states in India have been tested for neutralizing antibody against each of 15 different viruses known or believed to be arthropod borne. All tests with yellow fever, Bwamba fever, and Bunyamwera viruses were negative. A small number of sera were found which neutralized Ilhéus or Semliki Forest viruses, but neither of these agents appears to be of much importance in the localities sampled. Six of 211 sera neutralized St. Louis encephalitis virus. The same sera also neutralized West Nile virus. The interpretation of this result is not attempted. Antibodies against dengue types 1 and 2 and West Nile viruses were found in sera from residents of many localities; in some localities the incidence of protection was quite high. Significant numbers of the sera neutralized Zika, Uganda S, Nitaya, Japanese B, or Murray Valley virus. Six of 26 sera from donors living in the Sorath district of Saurashtra were protective against Russian spring-summer encephalitis virus. The question of possible group-specific reactions is discussed.

Experimental transmission of Russian spring-summer encephalitis virus by the mosquito.

Russian spring-summer encephalitis (RSSE), known as forest encephalitis or tick borne encephalitis, is disease Smorod.intseff and his co-workers (1) have made clear of its epidemiological aspects, causative agent, mode of infection and preventive measures during the years 1937-39. The disease prevails mainly in the Far-Eastern Russian terriory and is also reported since 1932 in European Russia and in Siberian woodlands. Kitano (2) has reported of the disease breaking out on the Manchuria-Soviet Frontiers and was successful to isolate the causative agent. Kitaoka (3) also mentioned that the disease was reported among those Japanese war prisoners engaging in wood-cutting at Sosoevka woods beyond the highlands in the north of Vladivostock in the II World War and the disease was found breaking out during the course of April 19 June 20, and about 10-16% of the total workers have contracted it, resulting in 19-50% casemortality. Symptoms, after invasion of the virus, and as far as to the studies on the neutralizing antibody in the convalescent serum are discussed about in, the report too.The virus is spread by Ixodes persulcatus Schuize, a species of wood tick and it was also made clear by Pavlovsky (4) that Eutamia asiatica, a rodent, is known as reservoir.Casals (5) and Hammon (6) have described that causal agent is not single and there are two types, the Far Eastern and the Western types, which Kitaoka (3) has also approved by the neutralizing test with the convalescent serum from the RSSE patient and has made clear that the former type is peculiar in the nervous disturbances and extrapyramidal symptoms, while the latter chiefly presents symptoms from irritations on meninges (Yamazaki) .Smorod intseff (1) has mentioned of the disease being not spread by mosquitoes. But it is of interest to see if it may be transmitted by mosquitoes because the vector of the encephalitis occurring in summer season is, as Hammon (6) and Kitaoka (7) have mentioned, mainly a mosquito. The RSSE prevails most vigorously during late. spring towards the summer when mosquitoes grow thrivingly. Well an experimental study on transmission by mosquitoes of the RSSE viruses namely, the Sophy strain (Far Eastern type) and a Western type, which were given from Dr. Hammon was carried out.

Failure of Trypan Red to Protect Against Certain Neurotropic Viruses ("M.M." and Russian Spring-Summer Encephalitis).

Trypan red failed to produce a significant protection against Russian Spring-summer encephalitis virus and “M.M.” virus when the dye was injected subcutaneously and the virus was inoculated by the intraperitoneal route. These experiments fail to confirm the results of others who injected both dye and virus intraperitoneally. We interpret the apparent protective effect obtained by Wood and Rusoff as being due to a well recognized and non-specific peritoneal protection afforded by certain inert substances when injected previous to the inoculation of infectious agents by the same route. Our results suggest that these two neurotropic viruses do not enter the central nervous system directly by way of the vascular channels as is the case with such an agent as cocaine, the passage of which into the central nervous system tissue may be altered by trypan red.

RELATIONSHIP OF THE VIRUS OF LOUPING ILL IN SHEEP AND THE VIRUS OF RUSSIAN SPRING-SUMMER ENCEPHALITIS IN MAN

An experimental study of three strains of Russian spring-summer encephalitis virus and one of louping ill virus has yielded the following results:- 1. The sera of mice hyperimmunized to the viruses of Russian encephalitis and louping ill respectively have produced complement fixation with both antigens in almost precisely the same titer. 2. In neutralization tests hyperimmune sera against the Russian virus strains protected against louping ill virus to the same extent as against the Russian virus strains. Conversely, hyperimmune sera against the louping ill virus protected against the Russian viruses, although to a less degree than against louping ill virus. 3. In cross-resistance tests in mice, a vaccine consisting of formolized Russian virus gave strong protection against this latter and moderate protection against louping ill virus. Formolized louping ill virus gave moderate protection against infection with louping ill and considerably less against the Russian virus. 4. Serum from an individual recovered from a laboratory infection with louping ill virus contracted in 1933 gave positive complement fixation and neutralization tests with the Russian spring-summer encephalitis, as well as with louping ill virus. 5. Serum from a patient who became infected with either Russian or louping ill virus or both while working with the viruses in the laboratory in the fall of 1942, gave positive reactions on complement fixation and neutralization tests against them both. 6. No such similarities have been found with other central nervous system viruses. Hence it would appear that they are specific.