Intrinsic Factors Affecting Vector Competence of Mosquitoes for Arboviruses

Hardy, James L.; Houk, Edward J.; Kramer, Laura D.; Reeves, William C.

doi:10.1146/annurev.en.28.010183.001305

Cited by 464 publications

(433 citation statements)

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“…Titres ranged from 101 3A45 LD 50/ml, with the overall mean titres in newly emerged adults and fed male ticks being higher than those for engorged larvae and nymphae. DISCUSSION The concept of threshold levels of viraemia for arthropod infection was first established by Chamberlain and others in studies of mosquito transmission of Western and Eastern Equine Encephalitis viruses [16] and has since been extensively studied in several mosquito-virus systems [17]. In contrast to mosquitoes which feed and digest the bloodmeal rapidly, ticks feed over a period of several days during which there may be considerable change in the virus titre in the blood.…”

Section: Resultsmentioning

confidence: 99%

Viraemic transmission of Crimean-Congo haemorrhagic fever virus to ticks

et al. 1991

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SUMMARYIn order to determine the way in which vertebrates infected with CrimeanCongo haemorrhagic fever (CCHF) virus and potential ixodid tick vectors interact in nature, immature and adult ticks of several species were fed on viraemic mammals and then assayed for virus content at varying times after feeding. CCHF virus was not isolated from ticks of six species tested after feeding as adults and immature forms on sheep with viraemia of 102 -32 LD 50/ml, nor from larval ticks fed on guinea-pigs and white-tailed rats with viraemia of 1019-27 LD 50/ml. In contrast, virus was isolated from 10 of 152 pools of engorged adult ticks of 5 species that fed on cattle with viraemia of 101'-27 LD 50/ml and from 3 of 137 female ticks after oviposition. Infection was transmitted to larval and nymphal Hyalomma truncatum and H. marginatum rufipes, but not to Rhipicephalus evertsi evertsi, from a scrub hare with viraemia of 1042 LD 50/ml but only nymphal H. truncatum and H. m. rufipes became infected from scrub hares with viraemia of 102 6-2 7 LD 50/ml. Infection was transmitted trans-stadially in H. m. rufipes and H. truncatum infected as nymphae, and adult H. m. rufipes transmitted infection to a sheep. No evidence of transovarial transmission was found in larval progeny of ticks exposed to CCHF virus as adults on sheep and cattle or as immatures on scrub hares.

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Section: Resultsmentioning

confidence: 99%

Viraemic transmission of Crimean-Congo haemorrhagic fever virus to ticks

et al. 1991

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“…Many viruses infecting plants or vertebrates are transmitted by arthropod vectors in a circulative manner (Sylvester, 1980;Hardy et al, 1983;Ammar, 1993). This requires the virus to cross epithelial cells of the gut and salivary glands, and to resist the potentially hostile environment of the vector in which they may replicate.…”

Section: Discussionmentioning

confidence: 99%

Endosymbiotic bacteria associated with circulative transmission of potato leafroll virus by Myzus persicae

Heuvel¹,

Verbeek²,

Wilk³

1994

Journal of General Virology

201

118

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In order to understand the molecular mechanisms underlying circulative transmission of potato leafroll virus (PLRV) by aphids, we screened Myzus persicae proteins as putative PLRV binding molecules using a virus overlay assay of protein blots. In this way, we found that purified PLRV particles exhibited affinity for five aphid proteins. The one most readily detected has an M r of 63K, and was identified as symbionin. This is the predominant protein synthesized by the bacterial endosymbiont of the aphid and is released into the haemolymph. Since further studies clearly showed that PLRV particles also bind to native symbionin, it was envisaged that virus particles when acquired into the haemocoel of an aphid interact with symbionin. Inhibition of prokaryotic protein synthesis by feeding M.persicae nymphs on an antibiotic-containing artificial diet prior to PLRV acquisition reduced virus transmission by more than 70 %. The major coat protein of the virus was found to be degraded in the antibiotictreated aphids; this would obviously have resulted in an increased exposure of viral RNA to enzymic breakdown and concomitant loss of infectivity. For these reasons we conclude that endosymbiotic bacteria play a crucial role in determining the persistent nature of PLRV in the aphid haemolymph and that symbionin is probably the key protein in this interaction.

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“…Environmental temperature may have an effect on mosquito physiology and thus may also influence pathogen multiplication and transmission (9). Therefore, changes in environmental temperatures in the direction consistent with global warming trends may be expected to exacerbate the emergence or resurgence of a number of vector-borne diseases, such as malaria and dengue (8,10,11).…”

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confidence: 99%