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PubMed1990

A new arbovirus from Aedes albopictus, an Asian mosquito established in the United States.

Ten strains of a new arbovirus belonging to the Bunyamwera group (Bunyaviridae) were recovered from field-collected Aedes albopictus mosquitoes in Potosi, Missouri. This evidence indicates that this species may serve as an arbovirus vector in the United States. The urban-suburban distribution, aggressive biting behavior, and broad viral susceptibility of Ae. albopictus may lead to the transmission of viruses of known public health importance and perhaps of viruses hitherto not transmitted to humans because of the feeding pattern of their usual vectors.

Aedes↗
PubMed1970

Comparison of methods for removal of nonspecific inhibitors of arbovirus hemagglutination.

Human sera were treated with kaolin, acetone, and dextran sulfate to determine the best method for removing nonspecific hemagglutination inhibitors. Results indicated that on surveys for group A, group B, and some group C arbovirus HI antibodies, dextran sulfate treatment of sera could be used effectively. This method, however, has limited usefulness for detecting HI antibody for a number of arboviruses, particularly some members of the Bunyamwera supergroup since nonspecific inhibitors for these antigens were not completely removed. HI antibodies in sera drawn early after dengue and Venezuelan equine encephalitis infection were detected more readily after dextran sulfate treatment than after kaolin treatment. Kaolin, but not dextran sulfate, was shown to remove antibody from IgM fractions of sera.

Absorption↗
PubMed1973

Resistance to arbovirus challenge in mice immediately after vaccination.

Mice vaccinated with a single injection of formalin-inactivated suspensions of mouse brain tissue infected with arboviruses were markedly protected against a challenge injection administered hours later. The protection observed during the first 2 days after vaccination seemed to be nonspecific, in that it appeared not only with the homologous system but also between arboviruses of different antigenic groups; this phase may be associated with an interferon-like activity of the serum. Overlapping the nonspecific phase was one of specific protection, which seemed to be well-established in its own right by day 3 or 4 after vaccination. Serum neutralizing antibodies against the homologous viruses were detected as early as 24 h after vaccination and in almost all instances by day 3.

Animals↗
PubMed1999

Genetic and fitness changes accompanying adaptation of an arbovirus to vertebrate and invertebrate cells.

The alternating host cycle and persistent vector infection may constrain the evolution of arboviruses. To test this hypothesis, eastern equine encephalitis virus was passaged in BHK or mosquito cells, as well as in alternating (both) host cell passages. High and low multiplicities were used to examine the effect of defective interfering particles. Clonal BHK and persistent mosquito cell infections were also evaluated. Fitness was measured with one-step growth curves and competition assays, and mutations were evaluated by nucleotide sequencing and RNA fingerprinting. All passages and assays were done at 32 degrees C to eliminate temperature as a selection factor. Viruses passaged in either cell type alone exhibited fitness declines in the bypassed cells, while high-multiplicity and clonal passages caused fitness declines in both types of cells. Bypassed cell fitness losses were mosquito and vertebrate specific and were not restricted to individual cell lines. Fitness increases occurred in the cell line used for single-host-adaptation passages and in both cells for alternately passaged viruses. Surprisingly, single-host-cell passage increased fitness in that cell type no more than alternating passages. However, single-host-cell adaptation resulted in more mutations than alternating cell passages. Mosquito cell adaptation invariably resulted in replacement of the stop codon in nsP3 with arginine or cysteine. In one case, BHK cell adaptation resulted in a 238-nucleotide deletion in the 3' untranslated region. Many nonsynonymous substitutions were shared among more than one BHK or mosquito cell passage series, suggesting positive Darwinian selection. Our results suggest that alternating host transmission cycles constrain the evolutionary rates of arboviruses but not their fitness for either host alone.

Adaptation, Biological↗
PubMed2001

Murray Valley encephalitis virus surveillance and control initiatives in Australia. National Arbovirus Advisory Committee of the Communicable Diseases Network Australia.

Mechanisms for monitoring Murray Valley encephalitis (MVE) virus activity include surveillance of human cases, surveillance for activity in sentinel animals, monitoring of mosquito vectors and monitoring of weather conditions. The monitoring of human cases is only one possible trigger for public health action and the additional surveillance systems are used in concert to signal the risk of human disease, often before the appearance of human cases. Mosquito vector surveillance includes mosquito trapping for speciation and enumeration of mosquitoes to monitor population sizes and relative composition. Virus isolation from mosquitoes can also be undertaken. Monitoring of weather conditions and vector surveillance determines whether there is a potential for MVE activity to occur. Virus isolation from trapped mosquitoes is necessary to define whether MVE is actually present, but is difficult to deliver in a timely fashion in some jurisdictions. Monitoring of sentinel animals indicates whether MVE transmission to vertebrates is actually occurring. Meteorological surveillance can assist in the prediction of potential MVE virus activity by signalling conditions that have been associated with outbreaks of Murray Valley encephalitis in humans in the past. Predictive models of MVE virus activity for south-eastern Australia have been developed, but due to the infrequency of outbreaks, are yet to be demonstrated as useful for the forecasting of major outbreaks. Surveillance mechanisms vary across the jurisdictions. Surveillance of human disease occurs in all States and Territories by reporting of cases to health authorities. Sentinel flocks of chickens are maintained in 4 jurisdictions (Western Australia, the Northern Territory, Victoria and New South Wales) with collaborations between Western Australia and the Northern Territory. Mosquito monitoring complements the surveillance of sentinel animals in these jurisdictions. In addition, other mosquito monitoring programs exist in other States (including South Australia and Queensland). Public health control measures may include advice to the general public and mosquito management programs to reduce the numbers of both mosquito larvae and adult vectors. Strategic plans for public health action in the event of MVE virus activity are currently developed or being developed in New South Wales, the Northern Territory, South Australia, Western Australia and Victoria. A southern tri-State agreement exists between health departments of New South Wales, Victoria and South Australia and the Commonwealth Department of Health and Aged Care. All partners have agreed to co-operate and provide assistance in predicting and combatting outbreaks of mosquito-borne disease in south-eastern Australia. The newly formed National Arbovirus Advisory Committee is a working party providing advice to the Communicable Diseases Network Australia on arbovirus surveillance and control. Recommendations for further enhancement of national surveillance for Murray Valley encephalitis are described.

Animals↗
PubMed1977

Antibodies to arboviruses in northwestern Spain.

A survey for antibodies to arboviruses was done in the human population of the north of Spain (provinces of La Coruña, Orense, Pontevedra, Leon, Asturias). Sera were obtained from 701 persons living in the area. The hemagglutination-inhibition (HI) test showed that 16.5% of the population studied had antibodies to group B arboviruses. All sera were negative for group A and Phlebotomus fever group viruses, as well as for Tahyna and Calovo. No evidence of antibody to tick-borne encephalitis viruses was found. Neutralization tests done with several group B viruses on 56 selected sera with HI antibodies confirmed an earlier infection with West Nile and probably one other group B virus not included in the test battery. A high rate of antibody was found in young persons, indicating that epidemic activity occurred between 1961 and 1970 in the area studied.

Adolescent↗
PubMed1977

Immune electron microscopy of arboviruses.

Representative members of four arbovirus taxons were studied by immune electron microscopy (IEM) in an attempt to determine whether the technique can be applied to the specific identification of arboviruses. Alphavirus, flavivirus, bunyavirus, and rhabdovirus antigens were prepared by propagation in tissue culture. The viruses were used to titrate homologous antibody and test heterologous antibody in the IEM test. Specific clumping together with visualization of antibody attachment was observed for all homologous systems studied. For the alphaviruses, titers of antibody, as determined by IEM, were comparable with the titers obtained by hemagglutination inhibition. Alphavirus cross-reactions were observed at low antibody dilutions by IEM. However, further dilution of antibody resulted in specific clumping only of homologous virus, allowing specific identification of alphavirus unknowns. For all viruses studied, positive IEM reactions were obtained with homologous grouping ascitic fluids but not with heterologous grouping fluids.

Antibodies, Viral↗
PubMed1979

Geographic distribution of arbovirus antibodies in indigenous human populations in the Indo-Australian archipelago.

Sera from lifetime residents in 16 localities of the Indo-Australian archipelago and adjacent areas were tested for hemagglutination-inhibition antibody against four alpha-viruses (Sindbis, Getah, chikungunya, and Ross River) and for neutralizing antibody against six flaviviruses (dengue 2 and 3, Japanese encephalitis, Murray Valley encephalitis, Kunjin, and Edge Hill). Mosquito collections were carried out in some of the localities to study vector relationships to distribution of the arbovirus antibodies. Antibodies specific to Sindbis and Getah viruses were rare except in north Australia. Chikungunya virus-specific antibody was highly prevalent in localities of the Oriental zoogeographic region and Wallacea, rare in west New Guinea, and absent in north Australia. Age distribution of chikungunya antibody suggested that the antibody last occurred in most Indonesian localities about 30 years ago. Ross River virus-specific antibody was confined to localities of the Australian zoogeographic region. Antibodies reacting to dengue 2 and 3 viruses occurred in high frequency in the entire area of the archipelago. Antibodies specific to Murray Valley encephalitis and Kunjin viruses were also widespread although at a very low frequency. Japanese encephalitis virus-specific antibody was highly prevalent in areas west of Wallace's Line while it was absent in areas east of the line with the exception of Lombok. Antibody to Edge Hill virus was rare and confined to the Australian zoogeographic region. The distribution of arthropod vectors, vertebrate hosts, and of arboviruses are discussed in relation to zoogeographic divisions.

Age Factors↗
PubMed2001

Partners: serendipity in arbovirus research.

A review of 60 years of research on mosquito-borne arboviruses in the Western U.S.A. revealed a number of instances when serendipity influenced the development of new concepts or novel approaches to solve ecological or epidemiological problems. Eight such events were selected as examples. The need for effective mosquito traps to collect live mosquitoes to be tested for virus infection posed design problems and also led to the use of CO2 (dry ice) as a mosquito attractant. This research also led to identification of Culex tarsalis as a primary target for vector control programs in the western U.S.A. Attendance at a movie led to development of fluorescent dusts to mark mosquitoes for studies of their numbers, life tables and movements. Knowledge of vector-virus associations was used to influence state legislative action to provide funding for vector control and further discovery of vector-virus associations. Derivation of the term "Arbovirus" started as laboratory jargon and evolved into being the classification for over 500 vector-borne viruses. Sociobiological changes resulting from the use of television and air conditioning fortuitously decreased exposure of California residents to vector attack. These two changes were introduced into households in California in the early 1950s. The prime time when C. tarsalis, the primary vector of encephalitis, bites people is around sundown which also is primetime for television watching. These sociological changes are a valuable adjunct to vector control programs.

Animals↗
PubMedDate not supplied

[Factors determining the antigenic activity of tissue cultures from arbovirus-infected diagnostic specimens].

Formation of arbovirus group A and B antigens is influenced significantly by the number of cells, time of monolayer growth before inoculation, the time of maximum accumulation of hemagglutinins, the infectious dose, the growth and maintenance medium composition, the autointerfering activity of the viruses and their sensitivity to tissue inhibitors. The stability of the hemagglutinating and complement-fixing properties of arbovirus diagnostic preparations does not depend upon the degree of concentration (7-12-fold) and the amount of the stabilizer (2-4%), and storage of group A diagnostic preparations in ampoules under vacuum or in ampoules sealed with air for 2-3 1/2 years (the observation period) does not influence their antigenic activity.

Arboviruses↗
PubMedDate not supplied

[Improved hemagglutination and hemagglutination inhibition tests for arboviruses].

The capacity of formalinized goose erythrocytes to be agglutinated in interactions with arboviruses was studied. Formalinized goose erythrocytes were found to be as sensitive as native erythrocytes, and were used successfully for diagnosis of arbovirus infections and study of the immune structure of the human population and animals. The superiority of formalinized erythrocytes is determined by the duration of storage (2 years of the observation period) withoug any change in the capacity for agglutination.

Arbovirus Infections↗
PubMed2003

[Investigation of Arboviruses in Lancang river down-stream area in Yunnan province].

OBJECTIVE: To investigate the epidemic state of arboviruses in the downstream area of Lancang river in Yunnan province. METHODS: Mosquitoes were collected from Lancang river downstream area (including Lancang county and Simao city) during summer in 1998 and stored in liquid nitrogen after classification. The mosquito pools were homogenized and centrifuged, then the supernatant was inoculated into C6/36 cells for virus isolation. New isolates were identified by neutralization test(NT), ELISA, immunofluorescence assay(IFA) and polyacrylamid gel electrophoresis(PAGE). RESULTS: Totally 22 isolates of arbovirus were obtained from 233 mosquito pools by inoculation of C6/36 cells and positive rate of the isolation was 9.4%. Ten strains were resistant to both ether and 5 prime-IDU. So they were non-enveloped double-stranded (ds) RNA virus. Twelve segmented RNAs were shown by PAGE and PAGE profiles from the ten strains were 6-6 with minor variation. The isolates can be neutralized by immunized mouse ascites fluid of BJ95-75 strains of coltivirus by NT, and reacted with monoclonal antibody against BJ95-75 by ELISA. These viruses were identified as coltivirus. Nine isolates were sensitive to ether and resistant to 5 prime-IDU. So they were non-enveloped RNA viruses. PAGE showed 10 segmented RNA, and they were identified to be orbiviruses. Three isolations were sensitive to ether. One of them can be neutralized with JEV A2 strain antibody by NT and was positive to the homologous antibody by IFA. It was identified being strain of JE virus. One strain(YN92-4) can be reacted with anti-bunyavirus group specific immune ascites fluid by both IFA and ElISA, but reacted neither with anti-alpha virus group, nor with anti-flavivirus group JE virus ascites fluid. The virions are spherical and about 87 nm in diameter with surface projections by negative staining. Conclusion Twenty-two isolates have been obtained from wild caught-mosquitoes of Lancang river down-stream area in Yunnan province. Among them ten, nine, one and one were identified as coltivirus, orbivirus, JE virus and bunyavirus, respectively. One is under identification. This is the first report on bunyavirus isolated from mosquitoes in China.

Animals↗
PubMedDate not supplied

[Chim virus, a new arbovirus isolated from ixodid and argasid ticks collected in the burrows of great gerbils on the territory of the Uzbek SSR].

Five strains of hitherto unknown arbovirus designated Chim by the place of primary collection of ticks was isolated from Ixodid and Argasid ticks collected in the Uzbek SSR in burrows of great gerbils. The virus has no antigenic relationships with arboviruses previously isolated from ticks, its size varies from 100 to 220 nm, it contains RNA and has a lipid-containing envelope. Chim virus is pathogenic only for suckling mice by the intracerebral route and exerts cytopathic effect in continuous L, Rh, BHK cell lines.

Animals↗
PubMed1975

Serologic examination of birds from the area of Southern Moravia for the presence of antibodies against arboviruses of the groups alfa, flavo, Bunyamwera supergroup, and the virus Yaba 1-Lednice 110. I. Domestic fowls.

196 geese, 141 ducks, and 100 hens from 9 localities of the South Moravian region (District of Breclav) were examined by means of the haemagglutination-inhibition test (HIT) for the presence of antibodies against 12 arbovirus antigens of the groups Alfavirus (Western Equine Encephalitis (WEE), Eastern Equine Encephalitis (EEE), Semliki, Sindbis, Chikungunya, O'nyong-nyong), Flavovirus (Tick-borne Encephalitis (TBE), Dengue and West Nile Virus (WN), Bunyamwera Supergroup (Tahna and Beta Calovo), and the Yaba 1-Lednice 110 Virus. In tested fowls antibodies were mostly found against Yaba 1-Lednice 110 Virus, namely 3.6% in geese and 17.7% in ducks. Antibodies against Calovo Virus were found in only 1 of the tested ducks. All sera of hens were negative. Antibodies against arboviruses of the Alfa-and Flavovirus groups were not detected.

Animals↗
PubMed1990

Arboviruses in the Iberian Peninsula.

The information concerning the presence and activity of arboviruses in the Iberian Peninsula is very scanty. In Portugal serological studies have been done with sera from animals, wild birds and human population. The results have shown that some arboviruses have been active in some areas of the territory. West Nile (WN) virus was isolated from mosquitoes and Dhori and Thogoto viruses have been isolated from ticks. In Spain, in spite of the large territory, it's geographical contiguity to Africa and the existence of different kinds of climates and ecologic conditions, the information is reduced to some surveys done in some restricted regions of the country. In both countries African swine fever was frequent and recently African horsesickness has been introduced to Southern Spain. A straight liaison and cooperation among virology laboratories of both countries and also Morocco should be emphasized in order to establish epidemiological surveillance in Southern Europe.

Animals↗
PubMed1975

The first isolations of eastern encephalitis, group C, and Guama group arboviruses from the Peruvian Amazon region of western South America.

Two strains of eastern encephalitis (EE) virus were isolated in the Amazon region of Peru near Pucallpa, Loreto Department, using sentinel hamsters. EE virus antibodies were found in healthy horses at both Pucallpa and Iquitos in the same Department. Fourteen group C and four Guama group arboviruses were recovered from sentenel hamsters and mosquitoes near Iquitos. The group C agents were Caraparu-Ossa, Marituba, and Oriboca-Itaqui viruses, and the Guama group agents were Bimiti virus. Besides providing a detailed account of these investigations, this article includes a current list of known arboviruses of the American tropics that can be detected with sentinel hamsters.

Animals↗
PubMed1975

A modified plaque method for arboviruses on plastic panels.

Autoclavable culture media containing an increased (10---15-fold)concentration of succinate buffer permit a comparitively long-term cultivation of cells in free gas exchange with the atmosphere. Based on them, an economical technique of plaque titration of arboviruses on plastic panels with methylcellulose overlay was developed. With seven arboviruses of three different groups and three cell lines (CV-1, PS and PK), the method proved sufficiently sensitive as compared with titrations in mice or tube cell cultures and suitable for plaque reduction tests.

Animals↗