Bunyamwera Group Virus Research Articles

Rapid detection of European orthobunyaviruses by reverse transcription loop-mediated isothermal amplification assays

The development of reverse transcriptase loop-mediated isothermal amplification (RT-LAMP) assays are described herein for the detection of two orthobunyaviruses (Bunyaviridae), which represent the two main serogroups found in mosquitoes in Central Europe. The RT-LAMP assays were optimized for the detection of Ťahyňa virus (a California encephalitis group virus found in Aedes sp or Ochlerotatus sp mosquitoes) and Batai virus (also called Čalovo virus, a Bunyamwera group virus found in Anopheles maculipennis s.l. mosquitoes) nucleic acid using endemic European virus isolates. The sensitivity of the RT-LAMP assays was determined to be comparable to that of conventional tests, with a limit of detection<0.1 pfu per reaction. The assays can be performed in 60min under isothermal conditions using very simple equipment. Furthermore, it was possible to proceed with the assays without nucleic acid extraction, albeit at a 100-fold loss of sensitivity. The RT-LAMP assays are a sensitive, cost-efficient method for both arbovirus surveillance as well as diagnostic laboratories to detect the presence of these endemic orthobunyaviruses.

Isolation of Rift Valley Fever Virus from Mosquitoes (Diptera: Culicidae) Collected During an Outbreak in Domestic Animals in Kenya

During an outbreak of Rift Valley fever (RVF) in livestock near Lake Naivasha, Rift Valley Province, Kenya, 61,347 mosquitoes (1,287 pools) collected in CO2-baited light traps yielded seven viral isolates. Five isolates of RVF virus were recovered from 18,831 Culex zombaensis Theobald and one from 14,439 Mansonia africana (Theobald). One isolate of a Bunyamwera group virus was recovered from 1,175 Aedes quasiunivittatus (Theobald).

Serologic evidence of arboviral infections in white-tailed deer from central Wisconsin.

A survey conducted during 1979-1980 on white-tailed deer (Odocoileus virginianus) in central Wisconsin revealed serological evidence of infection by selected arboviruses. Among sera from 41 deer, antibody was detected for Jamestown Canyon virus (56%) and Bunyamwera group virus (80%), demonstrating their continuing endemic activity. Antibody for La Crosse virus, not found previously in sera from deer in central Wisconsin, also was detected (5%) in this study.

Arbovirus Investigations in Argentina, 1977–1980

This is the introductory paper to a series on the ecology of arboviruses in Argentina. Epizootics of equine encephalitis have occurred since at least 1908, principally in the Pampa and Espinal biogeographic zones, with significant economic losses; human cases of encephalitis have been rare or absent. Both western equine and eastern equine encephalitis viruses have been isolated from horses during these epizootics, but the mosquitoes responsible for transmission have not been identified. A number of isolations of Venezuelan equine encephalitis (VEE) virus were reported between 1936 and 1958 in Argentina, but the validity of these findings has been seriously questioned. Nevertheless, serological evidence exists for human infections with a member of the VEE virus complex. Serological surveys conducted in the 1960s indicate a high prevalence of infection of humans and domestic animals with St. Louis encephalitis (SLE), and 2 SLE virus strains have been isolated from rodents. Human disease, however, has rarely been associated with SLE infection. Only 7 isolations of other arboviruses have been described (3 of Maguari, 1 of Aura, 2 of Una, and 1 of an untyped Bunyamwera group virus). In 1977, we began longitudinal field studies in Santa Fe Province, the epicenter of previous equine epizootics, and in 1980 we extended these studies to Chaco and Corrientes provinces. The study sites are described in this paper.

Virus isolations from mosquitoes in southern Ontario, 1976 and 1977.

Following the 1975 epidemic of St. Louis encephalitis (SLE) in Ontario, programs were instituted to monitor virus activity in mosquito populations during 1976 and 1977. Mosquitoes were trapped with CDC light traps and CO2 cone traps, pooled by species, and tested for virus by intracerebral inoculation of suckling mice. In 1976, 51 175 mosquitoes were tested. SLE virus was isolated from two mixed pools of Culex pipiens--C. restuans mosquitoes. Five isolations of California serogroup viruses were made. Three of these were trivittatus virus, which has not been demonstrated previously in Canada, and the other two were snowshoe have virus. Other viruses isolated in 1976 were a virus antigenically identical to the virus of infectious bursal disease of chickens and 34 Flanders viruses. In 1977, 34 428 mosquitoes were tested. Flanders virus was isolated most frequently, from pools of mixed C. pipiens--C. restuans mosquitoes. The only other isolate was a Bunyamwera group virus, Cache Valley virus. This virus has not been reported previously in Ontario.

Relationships of Bunyamwera Group Viruses by Neutralization *

A standardized serum dilution plaque reduction neutralization test was used for cross-neutralization studies of 23 strains of Bunyamwera serogroup viruses. Antigenic relationships were determined by inspection of the neutralization tests results as well as by numerical taxonomic analysis. Based on these analyses five complexes, containing 1-11 viruses, were distinguished. Little or no cross-reactivity was observed between viruses of different complexes. Three of the viruses tested were indistinguishable from prototypes and probably represent strains or varieties of those prototypes. A tentative classification scheme for the Bunyamwera group is presented.

Arthropod-borne viral infections of man in Nigeria, 1964-1970.

During the years 1964 to 1970, 171 arboviruses of 15 different types were isolated from humans in Nigeria. Isolation rates were highest in 1969, and lowest in 1965 and 1967. Monthly arbovirus activity was highest in the rainy season months of June, July and August and lowest in the dry months of January and February. Viruses were isolated from all age groups, with the majority from children one to four years old. The viruses isolated in largest numbers were chikungunya and yellow fever, which caused epidemics in 1969, and dengue types 1 and 2 and Tataguine, which are endemic in Ibadan. Bwamba virus was isolated in 1964 and 1969, and Bunyamwera group viruses were encountered for the first time in 1969. Other viruses recovered less frequently were Zika, Igbo-Ora (an agent related to o'nyong-nyong), two viruses related to the Uganda mosquito virus Ug MP 359, Dugbe, Thogoto, Lebombo and Shuni. Several of these are new agents and have not previously been isolated from man. Clinical details are presented where available.

Arbovirus infections in Sarawak, October 1968–February 1970: Human serological studies in a Land Dyak Village

449 human sera collected in a Land Dyak village were tested for antibodies to 11 arboviruses. Japanese encephalitis and dengue virus antibodies were particularly prevalent. The rates of infection with these viruses were estimated to be 5 · 2% per annum for Japanese encephalitis, 8 · 8% for dengue 1 and 4 · 3% for dengue 2. Chikungunya virus antibodies were quite common with an annual infection rate of the order of 5% per annum. Infections with other Group A and B and Bunyamwera group viruses were generally at a low level.

Arboviruses in Reptiles: Isolation of a Bunyamwera Group Virus from a Naturally Infected Turtle

A Bunyamwera group arbovirus was isolated from the blood of a naturally infected turtle, Trionyx spinifer emoryi, from South Texas. The virus could not be distinguished by neutralization tests from either Cache Valley or Tensaw viruses. The relationship of arboviruses and reptiles is reviewed.

Isolation of Bunyamwera-group viruses from Wisconsin mosquitoes.

Isolation of Bunyamwera-group viruses from Wisconsin mosquitoes.

Tensaw Virus, a New Member of the Bunyamwera Arbovirus Group from the Southern United States

Tensaw virus, a new member of the Bunyamwera arbovirus group (named for the river bordering the area in south Alabama where the prototype strain was found), is sensitive to sodium deoxycholate, relatively heat-stable at 37°C, and filterable through membranes with an APD of 220 millimicrons, but not through 100 millimicrons. The virus produced clinical disease and death in suckling and adult mice but did not produce disease in rabbits, guinea pigs, or hamsters. The virus grows well in hamster-kidney, HeLa, duck-embryo fibroblast, and monkey-kidney tissue-culture systems, producing cytopathic effects and plaques. Detailed antigenic comparison of eight strains of Tensaw virus with five known Bunyamwera-group viruses was made and the relation of the Tensaw strains to other Bunyamwera viruses was discussed.

St. Louis encephalitis vector studies in Houston, Texas, 1964.

Twenty-six isolations of arboviruses were made from 75,074 mosquitoes collected in Houston, Texas in 1964 during an outbreak of St. Louis encephalitis (SLE). Culex pipiens quinquefasciatus (Say) yielded 22 isolations of SLE virus, and one each of a California group and Flanders-related virus. One isolation of SLE virus and one of a Bunyamwera group virus were made also from Anopheles quadrimaculatus. The SLE vector species of the epidemic was concluded to be C. P. quinquefasciatus.

Isolation of Tlacotalpan virus, a new Bunyamwera-group virus from Mexican mosquitoes.

Summary Tlacotalpan virus, a new Bunyamwera-group virus, was recovered from Mansonia titillans, and closely related, probably identical viruses were isolated from Anopheles albimanus, An. spp., and Aedes taeniorhynchus mosquitoes collected during July and August 1961 and 1963 at Tlacotalpan, Veracruz, on the tropical southeastern coast of Mexico. This virus killed suckling and weanling mice, and produced plaques in primary chicken or duck embryonic-cell cultures and CPE in HeLa and L but not primary hamster-kidney-cell cultures. Neutralization tests of plasmas or sera revealed antibodies in persons at Tlacotalpan, in cattle and pigs at several locations along the tropical southeastern coast in Veracruz and Tabasco, and in one cow from the tropical western central coast in Nayarit. Thus Tlacotalpan virus infected man and domestic animals, but its disease-producing potentialities remain to be assessed.

THE ISOLATION AND IDENTIFICATION OF UKAUWA, A BUNYAMWERA GROUP VIRUS, FROM NIGERIA.

This paper reports the isolation and identification of Ukauwa virus, an agent closely related to the prototype Bunyamwera virus, from the serum of a Nigerian adult male suffering from a mild febrile illness.