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At least 19 recordsLinked to original sources
PubMed1975

Structural polypeptides of California encephalitis virus: BFS-283.

The polypepetides of California encephalitis virus (BFS-283) were analyzed by polyacrylamide gel electrophoresis (PAGE). Four polypeptides were detected in virions grown in both BHK-21 and LLC-MK2 cell cultures with molecular weights of 17,500. 30,000, 38,000, and 82,000 (VP-1, VP-2, VP-3, and VP-4, respectively). Viral proteins 2, 3, and 4 were glycoproteins and appeared to be associated with the envelope of the virus. Treatment of virions (rho=1.18 g/cm3) with then non-ionic detergent, NP-40, allowed detection of a RNA-rich fraction (rho=1.26/cm3) with contained the smallest polypeptides (VP-1).

Arboviruses↗
PubMed1975

California encephalitis virus prevalence throughout the Yukon Territory, 1971-1974.

California encephalitis (CE) virus (snowshoe hare subtype) was isolated from 1 of 38 pools comprising 970 unengorged female Aedes canadensis mosquitoes and from 3 of 152 pools containing 5,676 A. communis mosquitoes which were collected in the Yukon Territory, Canada between latitudes 61 and 66 degrees N during June and July 1974. During four summers 1971 through 1974, this virus was recovered from 26 of 648 pools derived from 30,686 mosquitoes of 4 species. Isolation of CE virus from 1 of 109 pools of Aedes sp. larvae collected during May 1974 suggests maintenance of this virus over winter by transovarial transfer. Infectivity has been maintained in Culiseta inornata mosquitoes which were held continuously at 32 degrees F for 138 days. Neutralizing antibodies to CE virus were detected in 705 of 4,913 (14%) mammals collected during summers 1971 through 1974, including 430 of 1,076 (40%) snowshoe hares (Lepus americanus), 266 of 3,610 (7%) ground squirrels (Citellus undulatus) and 9 of 227 (4%) red squirrels (Tamiasciurus hudsonicus).

Aedes↗
PubMed1978

California encephalitis virus activity in mosquitoes and horses in southern Ontario, 1975.

A study was undertaken in 1975 to determine California encephalitis virus activity in southern Ontario. Three thousand and sixty-one mosquitoes, primarily Aedes species, were divided into 104 pools and inoculated into suckling mice. Isolates of snowshoe hare virus were obtained from one pool each of Aedes fitchii and A. triseriatus mosquitoes collected in the Guelph area. Serological testing of horse sera revealed extensive virus activity in southern Ontario and indicated that horses may serve as excellent monitors for California encephalitis virus.

Aedes↗
PubMed1975

Isolation of La Crosse virus (California encephalitis group) from the chipmunk (Tamias striatus), an amplifier host.

La Crosse (LAC) virus was isolated from the blood of seven chipmunks (Tamias striatus) captured during the summer of 1970 in southwestern Wisconsin. With the exception of the original isolate obtained from human brain after fatal encephalitis, these represent the first known isolations of LAC virus from a naturally infected free-living vertebrate. The chipmunks were trapped and periodically recaptured in two study areas where 59 chipmunks became infected and developed neutralizing antibody during the summer cycle of virus transmission. All isolates were obtained from blood samples collected within a 7 week period between 11 July and 23 August, and all were from seronegative chipmunks; 6 of these were recaptured and found to be seropositive 2 to 3 weeks later. The isolates proved identical to each other in comparative micro-neutralization tests using BHK21 cell cultures and immune chipmunk serum or hyperimmune mouse ascitic fluids. Neutralization tests showed the isolates to be different from snowshoe hare, trivittatus, and Jamestown Canyon prototype virus strains but indistinguishable from the LAC prototype. Findings demonstrate multiplication and transmissibility of LAC virus in a naturally infected host and are consistent with the thesis that chipmunks are important amplifying hosts for LAC virus and that Aedes triseriatus mosquitoes serve as vectors in transmitting their infections. Ecological significance of the findings are discussed in regard to current perspectives.

Aedes↗
PubMed1977

California encephalitis virus transmission by arctic and domestic mosquitoes.

A zero passage arctic mosquito isolate of California encephalitis (CE) virus (showshoe hare subtype) was transmitted by wild-caught Aedes communis mosquitoes after 13 days incubation at 13 degrees and 23 degrees C, AFTER 20 days incubation at 13 degrees C, when mosquitoes imbibed 1 mouse LD50 in a blood meal. Transmission occurred after 20 days incubation at 13 degrees and 23 degrees C when mosquitoes were injected intrathoracially with 1 or 0.1 mouse LD50. Virus was also transmitted by A. aegypti 13 days after infection with 100 mouse LD50 by feeding or intrathoracic injection, and incubation at 13 degrees C. Virus antigen was detected in salivary glands of 42 percent virus-positive A communis mosquitoes by direct immunofluorescence, and in 50 percent or less of A aegypti mosquitoes by immunoperoxidase and immunofluorescence, with somewhat greater regularity by the indirect than the direct technique.

Aedes↗
PubMed1975

Ecology of California encephalitis viruses on the Del Mar Va Peninsula. I. Virus isolations from mosquitoes.

The ecology of California encephalitis viruses was studied on the Del Mar Va Peninsula. Adult mosquitoes were collected weekly from May to October of 1971 and monthly from May to October of 1972, using CDC miniature light traps with Dry Ice. Floodwater mosquitoes were assayed for virus in suckling mice or cell cultures. In 1971 over 77,000 mosquitoes were processed, resulting in 33 virus isolations. In 1972, over 106,000 were processed and 63 virus strains were recovered. Of the 1971 strains, all but one were recovered from Aedes atlanticus mosquitoes, and of the 1972 strains all but two were recovered from A. atlanticus. All A. atlanticus strains were neutralized by Keystone virus mouse hyperimmune ascitic fluid (MHAF). All other strains were recovered from A. canadensis mosquitoes. The single 1971 strain, and one strain from 1972, were neutralized by Jamestown Canyon MHAF. The remaining strain was neutralized by Keystone MHAF. The rate of virus recovery from A. atlanticus remained approximately the same, both between years and during each year studied, even during periods when large numbers of adults were emerging, suggesting that these mosquitoes had emerged infected.

Animals↗
PubMed1976

California encephalitis virus proliferation in Yukon mosquitoes incubated at low temperatures.

Replication of a subarctic Bunyavirus, California encephalitis (snowshoe hare subtype), was detected in salivary glands and thoraces of wild-caught Aedes communis mosquitoes from the Yokon Territory, after intrathoracic inoculation with 0.1 to 100 mouse LD50 virus, and incubation for 7 to 21 days throughout their viable temperature range of 0 to 23 degrees C. Immunoperoxidase staining confirmed that viral replication occurred in the cytoplasm of acinar cells of salivary glands, both by ligh microscopy and electron microscopy. Replication of another subarctic Bunyavirus, Northway, and a subtropical Flavivirus, Murray Valley encephalitis, was also demonstrated by infectivity by infectivity titrations and immun operoxidase reactions in salivary glands of A. communis incubated at 0, 13, and 23 degrees C for 7 to 21 days.

Aedes↗
PubMed1975

California encephalitis virus development in mosquitoes as revealed by transmission studies, immunoperoxidase staining, and electron microscopy.

Isolates of the snowshoe hare subtype of California encephalitis (CE) virus from Yukon mosquitoes during 1972 and 1973 were transmitted by bites of Aedes aegypti mosquitoes after 4 to 5 weeks of extrinsic incubation at 55 degrees F after intrathoracic injection, and the 1973 strain was transmitted after mosquitoes were fed virus and held for 3 to 4 weeks at 75 degrees F. Antigen of a 1971 isolate of CE virus (Marsh Lake 23) was detected in salivary glands of infected mosquitoes by the immunoperoxidase technique, using highly purified antiserum before and after conjugation with horseradish peroxidase, plus the use of orthotolidine as a substitute for benzidine. enveloped virions 45 nm in diameter were observed in thin sections of salivary glands of Culiseta inornata mosquitoes 59 days after intrathoracic injection with the 1971 isolate, afterincubation at 55 degrees F.

Aedes↗
PubMed1992

[A comparative experimental study of pathogenic properties of new strains of California encephalitis virus serogroups].

Experiments in noninbred mice, Syrian hamsters and grey monkeys were made to characterize the pathogenic properties of new strain of the California encephalitis serogroup isolated for the first time on the island of Taimir, in the Murmansk, Leningrad, Tver regions and in Karelia. All the strains displayed marked tropism for the CNS. The strains isolated in the northern regions of this country turned out more pathogenic for the animals. The strain Leiv-12812 Kl (isolated in the Tver region) differed from the remaining ones in more pronounced pathogenicity for the monkeys, as well as in the site and intensity of brain lesions. The persistence of the virus in hamsters organs may play a role of a reservoir of infection in nature.

Animals↗
PubMed1978

California encephalitis group viruses isolated from mosquitoes collected in Southern and Arctic Norway.

Three virus strains serologically related to the California encephalitis group (Bunyaviridae) of arboviruses were isolated from 7331 mosquitoes collected in Norway in June-August 1975. Two of the isolates (S 548 and S 618) seemed to be closely related and the third, S 568, more distantly related by serological techniques to Tahyna virus. Viruses were found in the mosquito species Aedes sticticus, A. diantaeus and A. hexodontus colllected (in order) from Oyern (59 degrees N, 11 degrees 12' E), Trandum (60 degrees 08' N, 11 degrees 10' E) and Masi (69 degrees 26' N, 23 degrees 39' E). The Masi isolate seems to be the northernmost arbovirus isolate in the world so far. Strain S 568 was from 16 male A. diantaeus, indicating transovarial transmission of the virus. An accidental infection demonstrated the potential human pathogenicity of one of the newly-isolated strains (S 568), and the ability of CE viruses to persistently infect suckling mouse brains was indicated by in vivo findings. The biological characteristics of the new strains so far investigated are consistent with those of the California encephalitis group. During this work the Aerosil absorption method for production of haemagglutinating antigens proved useful for Tahyna virus and the newly-isolated strains. Trypsinization of erythrocytes improved the haemagglutinating capacities of these viruses.

Animals↗
PubMed1975

Ecology of California encephalitis viruses on the Del Mar Va Peninsula. II. Demonstration of transovarial transmission.

The high rate of Keystone virus recovery from Aedes atlanticus collected in 1971 and 1972 suggested that these mosquitoes might be emerging infected. To demonstrate the suspected transovarial transmission of this virus, developmental stages of A. atlanticus were collected from the field. Larvae were identified and pooled for virus isolation in suckling mice. Pupae were allowed to emerge in the laboratory, then were segregated by sex and pooled for virus isolation. Keystone virus was recovered from larvae, reared males and reared females, demonstrating transovarial transmission of the Keystone strain of California encephalitis by A. atlanticus.

Aedes↗