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Biomedical subjects

G B Craig

Publications and source records attributed to G B Craig.

At least 37 records · Page 2Linked to original sources
PubMed1991

Transmission of a newly recognized virus (Bunyaviridae, Bunyavirus) isolated from Aedes albopictus (Diptera: Culicidae) in Potosi, Missouri.

Aedes albopictus (Skuse) mosquitoes collected in Potosi, Mo., were tested for their ability to transmit a newly recognized Bunyamwera sero group virus isolated from the same mosquito population. Mosquitoes were fed artificial blood meals containing 4.5-6.2 log10 TCID50 of virus per ml. After 7-29 d at 25 degrees C, 79-99% of the mosquitoes had disseminated infections and 0-26% transmitted virus to fluid-filled capillary tubes. Transmission was first observed after 7 d of extrinsic incubation. Tests failed to detect transovarial transmission in 5,145 progeny from ovarian cycles 2-4. Following parenteral inoculation with 5.3-6.0 log10 TCID50 of virus, four of nine adult hamsters developed viremia. Ten of 16 suckling mice died following intracerebral inoculation of 5.0 log10 TCID50 of virus (fifth Vero cell passage); the average survival time was 8.8 d (SD, 3.5). No mortality occurred in 10 suckling mice inoculated with 3.6 log10 TCID50 of virus (second Vero cell passage).

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PubMed1991

Antibodies to La Crosse virus in eastern chipmunks in Indiana near an Aedes albopictus population.

Blood samples of 34 Eastern chipmunks trapped in the vicinity of an Aedes albopictus population near New Alsace, IN, were tested for neutralizing antibodies to La Crosse (LAC) virus and other California group viruses. Two samples were positive for LAC antibodies. Analysis of mosquito bloodmeals demonstrated that both Ae. albopictus and Ae. triseriatus from the site fed on chipmunks. This note documents the first record of LAC antibodies in sylvan rodents from Indiana, the presence of LAC virus in the vicinity of Ae. albopictus and that wild Ae. albopictus feed on Eastern chipmunks.

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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.

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PubMed1989

Overwintering survival of Aedes albopictus (Diptera: Culicidae) eggs in Indiana.

Eggs of 12 strains of Aedes albopictus (Skuse), two strains of A. aegypti L., and one strain of A. triseriatus (Say) were tested for ability to overwinter at three outdoor locations in Indiana. Some survival of A. albopictus eggs was observed during the winters of 1986-1987 and 1987-1988. A. triseriatus had greater overwintering ability than A. albopictus; A. aegypti did not survive at all locations. Prolonged cold-conditioning and photoperiodically induced diapause increased the overwintering ability of A. albopictus eggs. Strains of A. albopictus from northern Asia and North America showed higher overwintering survival rates than A. albopictus strains from tropical Asia, Hawaii, and Brazil; strains from Indiana had greater ability to overwinter than those from Texas, Louisiana, and Florida. Results are discussed in relation to the overwintering limits of this species in the United States.

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PubMed1989

Midgut and salivary gland barriers to La Crosse virus dissemination in mosquitoes of the Aedes triseriatus group.

Vector competence for La Crosse virus (LACV) was compared for four species in the Aedes (Protomacleaya) triseriatus group: Ae. triseriatus (Say), Ae. hendersoni Cockerell, Ae. zoosophus Dyar and Knab and Ae. brelandi Zavortink (Diptera: Culicidae). Rates of replication and dissemination of virus in the mosquito hosts were compared and rates of oral transmission of virus to suckling mice were determined. Barriers to virus dissemination which limited the ability of each species to transmit virus were identified. Ae. zoosophus displayed the highest vector competence for LACV. Both infection and transmission rates were high: 99% and 85% respectively; no significant barriers to LACV were found. Disseminated infection of Ae. triseriatus with LACV was controlled primarily be a midgut escape barrier. When virus was introduced directly into the haemocoel, transmission rates were significantly increased (37% v. 79%). Ae. hendersoni showed high susceptibility to LACV infection but a very low rate of oral transmission (7%). Ae. brelandi was also highly susceptible to infection by LACV and transmitted virus at an intermediate rate (27%). Modulation of vector competence in both Ae. hendersoni and Ae. brelandi resulted from a salivary gland escape barrier. As these four species of mosquitoes comprise a closely related monophyletic series, their differences of vector competence for LACV provide an excellent model for studying the genetic basis of the barriers involved.

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PubMed1989

Recently introduced Aedes albopictus in the United States: potential vector of La Crosse virus (Bunyaviridae: California serogroup).

A population of Aedes albopictus collected in 1986 in Harris County, Texas, was evaluated for its vector competence with 4 California serogroup viruses (Jamestown Canyon, Keystone, La Crosse and trivittatus). Rates of midgut infection, dissemination of virus beyond the midgut and oral transmission to suckling mice were markedly different for the 4 viruses in a pattern representative of the antigenic relationships known for the California serogroup. Only La Crosse virus was shown to be efficiently transmitted by this recently introduced mosquito population. The results suggest that populations of Ae. albopictus originating from the Harris County population might well be as efficient in transmitting La Crosse virus as are populations of the natural mosquito vector. Aedes triseriatus, from the midwestern La Crosse virus enzootic region. The public health implications of these results are discussed in relation to the rapid spread of Ae. albopictus throughout the eastern half of the United States and into regions where La Crosse virus is known to be enzootic.

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PubMed1989

Further extension of the range of the rock pool mosquito, Aedes atropalpus, via tire breeding.

In the past, Aedes atropalpus was limited to those areas of the eastern U.S. and Canada that had rivers or shorelines with large rocks containing rock pools. In the last 10 years, many new records of larval breeding in scrap tires have accumulated. We present records of larval breeding in non-rock pool containers for 54 counties; most are far from the original range. The species has not only found a new habitat but has greatly extended its range via commercial transport of scrap tires.

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PubMed1988

Breeding structure of a colonizing species: Aedes albopictus (Skuse) in peninsular Malaysia and Borneo.

The mosquito, Aedes albopictus, has recently become established in a number of cities throughout the United States. An initial survey of allozyme and genotypic frequencies in U.S. populations (Black et al., 1988) revealed an extensive amount of local differentiation of populations and suggested that much genetic drift may have accompanied colonization. A study of gene flow was initiated in native habitats of Ae. albopictus in Malaysia to determine if the result observed in the U.S. was a consequence of colonization or simply followed the natural breeding structure of the species. Allelic and genotypic frequencies were monitored at ten enzymatic loci in 11 populations from peninsular Malaysia and Borneo. Multiple populations were sampled within the districts of Kuala Lumpur and Kuala Trengganu. Peninsular Malaysian and Borneo populations were strongly genetically differentiated. Allele frequencies were significantly different among and within districts in both regions. Variance in allele frequencies among all collections was partitioned into the variance among regions, districts within regions and collections within districts. Almost all of the variance within regions was attributable to local differentiation suggesting that genetic drift is an important component of the natural breeding structure of this species. This indicates that the large amounts of local differentiation found in U.S. populations was not a consequence of recent colonization.

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PubMed1988

Urban distribution of Aedes triseriatus in northern Indiana.

Ovitraps were used to determine the distribution of Aedes triseriatus among forty-eight 1.2 km2 quadrants in urban South Bend and Mishawaka, Indiana. Oviposition paddles from 96 ovitraps were collected for 13 weeks from June to September, 1986. A total of 82,974 eggs was collected. Eggs were present in each quadrant at least once and were found in most quadrants on 6 or more collection dates. Ninety-two percent of the ovitraps were positive at least once, indicating ubiquitous distribution throughout the urban area. The eggs collected were 80-90% Ae. triseriatus, the remainder being Ae. Hendersoni. Effectiveness of large (3,100 ml) and small (350 ml) ovitraps was compared. The large ovitraps exceeded the small by 319% for eggs/positive ovitrap and 486% in numbers of positive ovitraps.

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PubMed1987

Aedes albopictus in North America: probable introduction in used tires from northern Asia.

North American strains of Aedes albopictus, an Asian mosquito recently introduced into the Western Hemisphere, exhibit photoperiodic sensitivity and cold-hardiness characteristics similar to strains originating from temperate zone Asia. Trade statistics for used tire imports, the most likely mode of introduction, also indicate a north Asian origin. Aedes albopictus, an important vector of dengue and a potential vector of many other arboviral diseases, may therefore have the capability of infesting much of temperate North America.

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PubMed1987

Heterozygosity in inbred strains of the tree-hole mosquito Aedes triseriatus.

Inbred stocks of the tree-hole mosquito Aedes triseriatus from four localities were developed using full-sib mating. The progress of inbreeding was followed electrophoretically at eight variable and six less variable enzyme loci. Rates of fixation of several of these loci were substantially lower than expected. Discrepancies between observed and expected fixation values were evident in the early stages of inbreeding and became larger as inbreeding progressed. Odh, Hbd, Pgm, and Hk-4 were usually not fixed. By the F12 and F14 generations of brother-sister mating, most individuals in the two lines were heterozygotes (Odh and Hbd in the TK lines and Odh, Hbd, Pgm, and Hk-4 in the TV lines). The probability of maintaining heterozygosity at several selectively neutral and unlinked loci simultaneously is very low. Odh, Hbd, Pgm, and Hbd loci are linked to lethal recessives on chromosome 2, creating a balanced lethal system which in turn accounts for the heterozygosity in these inbred mosquitoes.

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PubMed1986

Identification of Aedes campestris from New Mexico: with notes on the isolation of western equine encephalitis and other arboviruses.

An arbovirus survey was conducted during August 1985 at White Sands Missile Range in southcentral New Mexico following a suspected arboviral disease epizootic among feral horses. A total of 20,566 mosquitoes (18,505 females and 2,061 males) and 8,900 biting gnats were collected and assayed for virus. Female mosquitoes were principally Aedes campestris (54.8%), Aedes dorsalis (30.4%) and Culex tarsalis (13.2%). Arboviruses were not isolated from biting gnats, but mosquitoes yielded a total of 37 viral isolates, including western equine encephalitis (WEE) (18), California serogroup (15), Cache Valey (1), and Hart Park (1) viruses in addition to 2, as yet unidentified, rhabdoviruses. Isolates of WEE virus were from 9 pools of Ae. campestris, 6 of Cx. tarsalis and 3 of Ae. dorsalis. California serogroup viruses, including 2 subtypes, were obtained from 7 pools of females and 1 pool of males of Ae. campestris and from 4 pools of Ae. dorsalis. Cache Valley and Hart Park viruses were isolated from single pools of Ae. dorsalis and Cx. tarsalis, respectively, and the rhabdoviruses were obtained from Ae. campestris and Psorophora signipennis.

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