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At least 343 records · Page 19Linked to original sources
PubMed1981

Bunyamwera virus replication in cultured Aedes albopictus (mosquito) cells: establishment of a persistent viral infection.

Bunyamwera virus replication was examined in Aedes albopictus (mosquito) cell cultures in which a persistent infection is established and in cytopathically infected BHK cells. During primary infection of A. albopictus cells, Bunyamwera virus reached relatively high titers ( approximately 10(7) PFU/ml), and autointerference was not observed. Three virus-specific RNAs (L, M, and S) and two virion proteins (N and G1) were detected in infected cells. Maximum rates of viral RNA synthesis and viral protein synthesis were extremely low, corresponding to <2% of the synthetic capacities of uninfected control cells. Viral protein synthesis was maximal at 12 h postinfection and was shut down to barely detectable levels at 24 h postinfection. Virus-specific RNA and nucleocapsid syntheses showed similar patterns of change, but later in infection. The proportions of cells able to release a single PFU at 3, 6, and 54 days postinfection were 100, 50, and 1.5%, respectively. Titers fell to 10(3) to 10(5) PFU/ml in carrier cultures. Persistently infected cultures were resistant to superinfection with homologous virus but not with heterologous virus. No changes in host cell protein synthesis or other cytopathic effects were observed at any stage of infection. Small-plaque variants of Bunyamwera virus appeared at approximately 7 days postinfection and increased gradually until they were 75 to 95% of the total infectious virus at 66 days postinfection. Temperature-sensitive mutants appeared between 23 and 49 days postinfection. No antiviral activity similar to that reported in A. albopictus cell cultures persistently infected with Sindbis virus (R. Riedel and D. T. Brown, J. Virol. 29: 51-60, 1979) was detected in culture fluids by 3 months after infection. Bunyamwera virus replicated more rapidly in BHK cells than in mosquito cells but reached lower titers. Autointerference occurred at multiplicities of infection of approximately 10. Virus-specific RNA and protein syntheses were at least 20% of the levels in uninfected control cells. Host cell protein synthesis was completely shut down, and nucleocapsid protein accumulated until it was 4% of the total cell protein. We discuss these results in relation to possible mechanisms involved in determining the outcome of arbovirus infection of vertebrate and mosquito cells.

Aedes↗
PubMed1987

Factors influencing the transmission of western equine encephalomyelitis virus between its vertebrate maintenance hosts and from them to humans.

A simple model is used to explore the extent to which the uniquely comprehensive studies of western equine encephalomyelitis in Kern County, California, by Reeves and his colleagues over many years, explain the dynamics and epidemiology of the infection. It is concluded that not only does this series of integrated field and laboratory studies successfully account for these phenomena, to an extent which is unlikely to be substantially improved upon, not least because of the inherent difficulties in measuring the key factors with greater precision; but it also provides a unique model of the dedication and ingenuity required if comparable levels of understanding of the ecology and epidemiology of other arbovirus infections are to be achieved.

Aedes↗
PubMed1969

Synthesis of Saint Louis encephalitis virus ribonucleic acid in BHK-21-13 cells.

Infection of baby hamster kidney cells (BHK-21/13) with Saint Louis encephalitis (SLE) virus depressed the rate of protein and ribonucleic acid (RNA) synthesis until viral RNA synthesis began 6 hr postinfection (PI). Virus-directed RNA synthesis was subsequently inhibited until 12 hr PI when virion maturation began. The rate of protein synthesis reached a peak 6 hr PI and was subsequently depressed until just before the onset of virion maturation. Density gradient analysis of phenol-extracted RNA from actinomycin-treated infected cells indicated that, at 6 to 8 hr and again at 12 to 20 hr PI, three species of viral-specific RNA were synthesized. The most rapid sedimenting form (43S) was ribonuclease-sensitive and had a base composition similar to the RNA isolated from mature virions. The 20S RNA species was ribonuclease-resistant and had a sedimentation coefficient and base composition similar to the replicative form associated with other arbovirus infections. The 26S RNA was ribonuclease-resistant (0.2 mug/ml, 0.1 m NaCl, 25 C, 30 min) and had a nucleotide base composition closer to the 20S form than to the values for 43S RNA. Five-minute pulse labeling of infected cultures during the period viral RNA synthesis was maximal resulted in labeling of only the 20S to 22S RNA fractions. With pulse-labeling periods of 10 min, both the 20S and 26S RNA species were radioactive. Periods of radioactive labeling of as long as 15 min were required before the 43S form was radioactively labeled. These results suggest that the 20S and 26S RNA may be intermediate forms in the synthesis of 43S viral RNA.

Animals↗
PubMed1989

[A survey of antibodies to arboviruses in residents in south-western part of Yunnan province].

In order to provide serological evidence for arbovirus infection in Yunnan province, 760 Samples of human sera collected from nine counties in south-western part of Yunnan province were examined for HI antibodies to 11 arboviral antigens. The viruses used in this experiment included 3 alphaviruses (MAY, VEE and CHIK) and 8 flaviviruses (JE, MVE, KUN, DEN3, DEN4, KFD, LGT and POW). 275 samples were found positive for HI antibodies to alphaviruses (36.2%) and 189 of them (68.7%) reacted with MAY virus, 61 (22.2%) with CHIK. The GMT of HI titers for VEE, MAY and Chik were 164.4, 94.5 and 66.7, respectively. 588 samples of sera (77.4%) were found positive for HI antibodies to flaviviruses. The positive HI antibody rates were as follows: JE, 27.9%; DEN, 36.6%; KFD, 22.2%; MVE, 22.1%; KUN, 18.7%; POW, 8.8% and LGT, 7.9%, respectively. Its average GMT was 356, and the antibody titers of 403 samples of sera were higher than 1/640. Cross reactions among viruses, especially flaviviruses, were usually found by HI test, and superinfections were present. In addition to the existence of JE and DEN viruses the results clearly showed that many Kinds of arboviruses might exist in Yunan Province.

Alphavirus↗
PubMed1984

Arbovirus studies in southwestern Venezuela during 1973-1981. II. Isolations and further studies of Venezuelan and eastern equine encephalitis, Una, Itaqui, and Moju viruses.

Increasing utilization of arable land in southwestern Venezuela has led to a potential increase in human exposure to arbovirus infections. Since previous studies in the Catatumbo region of this area documented the presence of eastern equine encephalitis (EEE) and Venezuelan equine encephalitis (VEE) viruses, an attempt was made to study the transmission and maintenance of these viruses from 1973 to 1981. Isolations of EEE, VEE ID strains, Una, Itaqui , and Moju viruses were repeatedly obtained from mosquitoes, mostly Culex ( Melanoconion ) spp. and sentinel hamsters. The results indicate that these viruses constitute a potential hazard to public health in the area. Further, the strategic location of the Catatumbo region, between enzootic tropical foci of arboviruses, may provide circumstances and conditions for study of both enzootic maintenance and movement of these viruses.

Aedes↗
PubMed2004

A survey of the relationships among the viruses not considered arboviruses, vertebrates, and arthropods.

No single group of organisms demonstrates more extensive and diverse associations with animal viruses than the phylum Arthropoda. Compared with the well-recognized relationship found in arboviruses, however, most of the atypical arthropod-vertebrate relationships of the viruses normally not considered arboviruses have received much less attention, as they remain in the marginal areas of interest for most researchers in animal virology, veterinary medicine, medical entomology, and invertebrate pathology. However, this comprehensive review of the information gathered from several branches of virology by profession reveals highly valuable information potentially useful in the fields of research ranging from investigations of the mode of transmission of poorly understood or emerging viral diseases to studies of the evolution of biological transmission of animal viruses by arthropod vectors. The observations and data obtained for the animal virus relationships with arthropods and vertebrates outside the boundaries of arboviruses, in turn, can be used to reexamine more closely the definition of arboviruses. With increasing number of reports challenging one of the basic tenets of the definition of arbovirus (requirement of viremia in vertebrate host) and others describing virus-host relationships that complicate the definition of arbovirus, the accumulated information clearly demonstrates the difficulty of defining the boundaries of arboviruses.

Animals↗
PubMed1994

Threat of hepatitis E virus infection in Somalia during Operation Restore Hope.

In support of Operation Restore Hope, the United States military established a diagnostic laboratory for infectious diseases, the Joint Forward Laboratory, in Mogadishu, Somalia. Because sporadic hepatitis due to unknown causes was a frequent problem, staff members of the Joint Forward Laboratory evaluated 31 Somalis, five displaced Ethiopians, and three Western relief workers who had acute clinical hepatitis. Patients lived in multiple locations in Somalia--Mogadishu, Baidoa, and Merca--and became ill between December 1992 and February 1993. IgM antibody to hepatitis A virus was found in one English relief worker, and IgM antibody to hepatitis E virus was found in 20 (65%) of 31 Somalis, two (40%) of five Ethiopians, and two (67%) of three Western relief workers. No patient had evidence of acute hepatitis B, malaria, yellow fever, or other arbovirus infections. These data indicate that hepatitis E virus--the major cause of enterically transmitted non-A, non-B hepatitis--was a common cause of acute sporadic hepatitis in Somalia during the initial stages of Operation Restore Hope.

Disease Outbreaks↗
PubMedDate not supplied

The prevalence of arboviral, rickettsial, and Hantaan-like viral antibody among schoolchildren in the Nile river delta of Egypt.

A serosurvey was conducted during October and November 1989 to estimate the prevalence of selected arboviral, rickettsial, and Hantaan viral antibody among a sample of schoolchildren from 4 villages in the Bilbeis area of the Nile river delta, Egypt. Blood specimens were obtained from subjects aged 8 to 14 years. Enzyme immunoassay testing of the sera indicated that the prevalence of antibody was 9% (21/223) for Sicilian sandfly fever, 4% (8/223) for Rift Valley fever, 3% (15/437) for West Nile virus and 9% (28/315) for Hantaan (HTN) virus. Antibody was demonstrated among 22% (93/418) of the same study subjects against Coxiella burnetti, 53% (199/373) against Rickettsia typhi, and 37% (137/371) against R. conorii.

Adolescent↗
PubMed2000

Langerhans cells migrate to local lymph nodes following cutaneous infection with an arbovirus.

Whereas there has been recent interest in interactions between dendritic cells and pathogenic viruses, the role of dendritic cells in the initiation of protective immunity to such organisms has not been elucidated. The aim of this study was to examine whether a resident dendritic cell population in the skin, Langerhans cells, respond to cutaneous viral infections which are effectively cleared by the immune system. We therefore characterized the ability of Langerhans cells to migrate to local draining lymph nodes following infection with the arthropod-borne viruses, West Nile virus or Semliki Forest virus. The data show that major histocompatibility complex class II+/NLDC145+/E-cadherin+ Langerhans cell numbers are increased in the draining lymph nodes of infected mice and this increase is accompanied by a concomitant decrease in the Langerhans cell density in the epidermis. Langerhans cell migration is associated with an accumulation of leukocytes in the lymph node, which is one of the earliest events in the initiation of an immune response. Both the migratory response and the draining lymph node leukocyte accumulation were abrogated if ultraviolet-inactivated instead of live viruses were used, suggesting the activation and subsequent migration of Langerhans cells requires a live, replicating antigen. Our findings are likely to have wider implications for the development of epidermally delivered vaccines and suggest that mobilization of dendritic cells may be involved in the development of immune responses to arthropod-borne viruses.

Alphavirus Infections↗
PubMed1982

Blood brain barrier disturbance and immunoglobulin G levels in the cerebrospinal fluid of the mouse following peripheral infection with the demyelinating strain of Semliki Forest virus.

Immunoglobulin G and albumin levels have been measured in the cerebrospinal fluid and serum of Swiss A2G mice following single intraperitoneal inoculation of Semliki Forest virus. This strain of virus used causes a meningoencephalitis followed by immunologically-mediated demyelination. By the use of the levels of immunoglobulin G and albumin in cerebrospinal fluid and serum to calculate the cerebrospinal fluid: serum ratios and the cerebrospinal fluid immunoglobulin G index, it has been shown that the blood-brain barrier breakdown is mild and restricted to within the first 7-8 days after virus inoculation when the inflammatory response is maximal. Immunoglobulin G index provides a measure of synthesis of immunoglobulin G within the blood-brain barrier. Synthesis has been shown to occur from day 10 onwards up to at least day 61 following infection. Arboviruses are known to persist in central nervous system tissue and it is suggested that a continuing immune response within the central nervous system occurs and is perpetuated by persisting virus. Because of the mode of replication of Semliki Forest virus it is also possible that some of the immune response is directed against central nervous system components.

Animals↗
PubMed1990

Entry of neurotropic arboviruses into the central nervous system: an in vitro study using mouse brain endothelium.

Arbovirus infection of cerebral microvascular endothelial cells was investigated in an in vitro mouse brain endothelial (MBE) cell model. Alphaviruses replicated to a greater extent than did flaviviruses, indicating that viremia may be important in neuroinvasion. Also, some viruses (e.g., Semliki Forest virus) replicated to high titers while others (e.g., Murray Valley encephalitis virus) did not. Viruses that replicated to high titers showed luminal polarity of virus release, indicating that infection of the endothelium may be important in both maintenance of viremia and neuroinvasion; viruses that did not so replicate showed abluminal polarity of release, indicating that virus is actively transported across the endothelial monolayer, another mechanism for neuroinvasion. Infection of MBE cells with highly and less-neuroinvasive strains achieved similar results, indicating that the endothelium does not discriminate between neuroinvasive strains. However, the cerebral microvascular endothelium may be important in discriminating between viruses that invade the brain parenchyma and those that do not: neuron-tropic Ross River virus T48 replicated to higher titers than did ependymal-tropic Ross River virus NB5092. Thus, viruses probably use multiple cellular mechanisms to invade the central nervous system across the cerebral microvascular endothelium.

Alphavirus↗
PubMed1993

[Virologic detection of arboviruses in greater cormorants].

Cormorants (Phalacrocorax carbo, Pelecaniformes) caught in southern Moravia (Czech Republic) in 1989-1990 were examined for arbovirus infections. Isolation experiments were carried out using blood samples of 56 birds. The results were negative. Serological examinations of 31 birds were performed by haemagglutination-inhibition test (HIT) using 5 arboviral antigens of the genera Alphavirus (Sindbis--SIN) and Flavivirus (tick-borne encephalitis--TBE, West Nile--WN) and of the family Bunyaviridae (Tahyna--TAH, Calovo--CVO). Antibodies were detected only to viruses SIN, WN and TAH at different frequencies: 9.7%, 9.7% and 22.6%. The titres ranged from 1:20 to 1:80.

Animals↗
PubMed2026

Widespread circulation of Alongshan virus in Austria and serological evidence for infection in humans: a nationwide molecular and serological observational study.

BACKGROUND: Alongshan virus, a segmented RNA virus in the Jingmenvirus group of flaviviruses, was first identified in 2017 in China in patients with tick-borne encephalitis-like illness. Alongshan virus has since been detected in ticks and mammals in several European countries. In this study, we aimed to characterise the temporal and geographical distribution of Alongshan virus in Austria through nationwide tick surveillance combined with serological and molecular screening in individuals with suspected tick-borne encephalitis or tick exposure. METHODS: In this nationwide molecular and serological observational study, we conducted a PCR-based screening of ticks collected across Austria in 2024, using flagging, animal hosts, and citizen submissions. We also collated genomic data from stored nucleic acid extracts from ticks collected in Austria in 2005 and 2013 in previous surveillance studies and stored extracts of paired tick-human samples collected between 2015 and 2018. Alongshan virus-positive tick samples were subjected to whole-genome sequencing and phylogenetic analysis. In addition to tick samples, blood samples from Austrian patients with reported tick bite or suspected tick-borne encephalitis, submitted to the National Reference Center for Human Arbovirus Infections, Austria, were screened for Alongshan virus infection and subjected to serological and molecular testing. FINDINGS: 2952 ticks were collected between Feb 1, 2024, and Dec 6, 2024, from 29 (83%) of 35 NUTS-3 regions in Austria; the median detection rate for Alongshan virus was 1&#xb7;2% (IQR 0&#xb7;4-3&#xb7;5). In addition, 1816 archived tick samples were analysed, with three testing positive for Alongshan virus. For the virus-positive samples, phylogenetic analysis showed that sequences from Austria grouped within the European clade, with Austrian sequences from the same region showing high sequence similarity. 1361 human serum samples collected between March 1, 2023, and May 16, 2025, were assessed for anti-Alongshan virus IgG antibodies. Two individuals had high antibody titres against Alongshan virus proteins VP1a and VP2. INTERPRETATION: Our study shows detection of Alongshan virus in archived tick samples dating back to 2005, representing the earliest documented occurrence of the virus to date and suggesting that Alongshan virus has been circulating in Austria for at least two decades. The detection of Alongshan virus-specific antibody titres in two individuals suggests past infection and previously unrecognised exposure. These results highlight the need for continued molecular surveillance of tick populations and serological monitoring in humans to define the epidemiology and public health relevance of Alongshan virus in Europe. FUNDING: One Health surveillance and Vector monitoring for cross-border pathogens (OH SURVector) and UNITED4Surveillance.

Adolescent↗