Dissemination barriers for western equine encephalomyelitis virus in Culex tarsalis infected after ingestion of low viral doses.
01 Jan 1981-American Journal of Tropical Medicine and Hygiene (The American Society of Tropical Medicine and Hygiene)-Vol. 30, Iss: 1, pp 190-197
TL;DR: There are two dose-dependent barriers to the transmission of western equine encephalomyelitis virus in infected female Culex tarsalis and the distribution of virus in the tissues of nontransmitting females with either of these barriers is described.
Abstract: There are two dose-dependent barriers to the transmission of western equine encephalomyelitis virus in infected female Culex tarsalis. In the first, virus multiplies in the mesenteron, but does not invade other tissues regardless of the length of extrinsic incubation. We call this the "mesenteronal escape" barrier. In some mosquitoes virus escapes from the infected mesenteron but a second barrier prevents infection of the salivary glands and perhaps neural tissues. We designate this the "salivary gland infection" barrier. The effectiveness of the second barrier decreases with time but still is evident after 21 days of extrinsic incubation. The distribution of virus in the tissues of nontransmitting females with either of these barriers is described.
Citations
More filters
Book•
16 May 1991
TL;DR: This chapter discusses the evolution of the blood-sucking habit, feeding preferences, host-insect interactions, and the transmission of parasites by blood-Sucking insects.
Abstract: Part 1 The importance of blood-sucking insects. Part 2 The evolution of the blood-sucking habit: prolonged close association with vertebrates morphological pre-adaptation for piercing. Part 3 Feeding preferences of blood-sucking insects: host choice host choice and species complexes. Part 4 Location of the host: the behavioural framework of host location appetitive searching activation and orientation attraction movement between hosts. Part 5 Ingestion of the blood meal: vertebrate haemostasis insect anti-haemostatic factors probing stimulants phagostimulants mouthparts blood intake. Part 6 Managing the blood meal: midgut anatomy the blood meal gonotrophic concordance nutrition host hormones in the blood meal partitioning of resources from the blood meal autogeny. Part 7 Host - insect interactions: insect distribution on the surface of the host morphological specializations for life on the host host immune responses to insect salivary secretions behavioural defences of the host density dependent effects on feeding success. Part 8 Transmission of parasites by blood-sucking insects: transmission routes specificity in vector-parasite relationships origin of vector parasite relationships.
772 citations
Cites background from "Dissemination barriers for western ..."
...Even after successful infection of the gut epithelium, the virus may be prevented from infecting the haemocoel by the ‘mesenteronal escape barrier’, and the salivary glands by the ‘salivary gland infection barrier’ (Kramer et al., 1981)....
[...]
TL;DR: In determining the potential for a mosquito species to become involved in transmitting WNV, it is necessary to consider not only its laboratory vector competence but also its abundance, host-feeding preference, involvement with other viruses with similar transmission cycles, and whether WNV has been isolated from this species under natural conditions.
Abstract: Since first discovered in the New York City area in 1999, West Nile virus (WNV) has become established over much of the continental United States and has been responsible for >10,000 cases of severe disease and 400 human fatalities, as well as thousands of fatal infections in horses. To develop appropriate surveillance and control strategies, the identification of which mosquito species are competent vectors and how various factors influence their ability to transmit this virus must be determined. Therefore, we evaluated numerous mosquito species for their ability to transmit WNV under laboratory conditions. This report contains data for several mosquito species not reported previously, as well as a summary of transmission data compiled from previously reported studies. Mosquitoes were allowed to feed on chickens infected with WNV isolated from a crow that died during the 1999 outbreak in New York City. These mosquitoes were tested approximately 2 wk later to determine infection, dissemination, and transmission rates. All Culex species tested were competent vectors in the laboratory and varied from highly efficient vectors (e.g., Culex tarsalis Coquillett) to moderately efficient ones (e.g., Culex nigripalpus Theobald). Nearly all of the Culex species tested could serve as efficient enzootic or amplifying vectors for WNV. Several container-breeding Aedes and Ochlerotatus species were highly efficient vectors under laboratory conditions, but because of their feeding preferences, would probably not be involved in the maintenance of WNV in nature. However, they would be potential bridge vectors between the avian-Culex cycle and mammalian hosts. In contrast, most of the surface pool-breeding Aedes and Ochlerotatus species tested were relatively inefficient vectors under laboratory conditions and would probably not play a significant role in transmitting WNV in nature. In determining the potential for a mosquito species to become involved in transmitting WNV, it is necessary to consider not only its laboratory vector competence but also its abundance, host-feeding preference, involvement with other viruses with similar transmission cycles, and whether WNV has been isolated from this species under natural conditions.
644 citations
Cites background from "Dissemination barriers for western ..."
...This indicated that midgut infection and escape barriers (Kramer et al. 1981) seem to be the principal factors controlling vector competence with WNV....
[...]
TL;DR: The potential for several North American mosquito species to transmit the newly introduced West Nile (WN) virus is evaluated, and laboratory vector competence, host-feeding preferences, relative abundance, and season of activity determine the role that these species could play in transmitting WN virus.
Abstract: We evaluated the potential for several North American mosquito species to transmit the newly introduced West Nile (WN) virus. Mosquitoes collected in the New York City metropolitan area during the recent WN virus outbreak, at the Assateague Island Wildlife Refuge, VA, or from established colonies were allowed to feed on chickens infected with WN virus isolated from a crow that died during the 1999 outbreak. These mosquitoes were tested ≈2 wk later to determine infection, dissemination, and transmission rates. Aedes albopictus (Skuse), Aedes atropalpus (Coquillett), and Aedes japonicus (Theobald) were highly susceptible to infection, and nearly all individuals with a disseminated infection transmitted virus by bite. Culex pipiens L. and Aedes sollicitans (Walker) were moderately susceptible. In contrast, Aedes vexans (Meigen), Aedes aegypti (L.), and Aedes taeniorhynchus (Wiedemann) were relatively refractory to infection, but individual mosquitoes inoculated with WN virus did transmit virus by bite. Infected female Cx. pipiens transmitted WN virus to one of 1,618 F1 progeny, indicating the potential for vertical transmission of this virus. In addition to laboratory vector competence, host-feeding preferences, relative abundance, and season of activity also determine the role that these species could play in transmitting WN virus.
616 citations
TL;DR: Of more than 500 arboviruses recognized worldwide, 5 were firstisolated in Canada and 58 were first isolated in the United States, and six of these viruses are human pathogens: western equine encephalitis and eastern equineencephalitis (WEE) viruses (family Togaviridae, genus Alphavirus), St. Louis encephalopathy (SLE) and Powassan (POW) viruses, LaCrosse (LAC) virus, La
Abstract: Of more than 500 arboviruses recognized worldwide, 5 were first isolated in Canada and 58 were first isolated in the United States. Six of these viruses are human pathogens: western equine encephalitis (WEE) and eastern equine encephalitis (EEE) viruses (family Togaviridae, genus Alphavirus), St. Louis encephalitis (SLE) and Powassan (POW) viruses (Flaviviridae, Flavivirus), LaCrosse (LAC) virus (Bunyaviridae, Bunyavirus), and Colorado tick fever (CTF) virus (Reoviridae, Coltivirus). Their scientific histories, geographic distributions, virology, epidemiology, vectors, vertebrate hosts, transmission, pathogenesis, clinical and differential diagnoses, control, treatment, and laboratory diagnosis are reviewed. In addition, mention is made of the Venezuelan equine encephalitis (VEE) complex viruses (family Togaviridae, genus Alphavirus), which periodically cause human and equine disease in North America. WEE, EEE, and SLE viruses are transmitted by mosquitoes between birds; POW and CTF viruses, between wild mammals by ticks; LAC virus, between small mammals by mosquitoes; and VEE viruses, between small or large mammals by mosquitoes. Human infections are tangential to the natural cycle. Such infections range from rare to focal but are relatively frequent where they occur. Epidemics of WEE, EEE, VEE, and SLE viruses have been recorded at periodic intervals, but prevalence of infections with LAC and CTF viruses typically are constant, related to the degree of exposure to infected vectors. Infections with POW virus appear to be rare. Adequate diagnostic tools are available, but treatment is mainly supportive, and greater efforts at educating the public and the medical community are suggested if infections are to be prevented.
388 citations
TL;DR: A population genetic model for vector competence is proposed and recent progress in testing this model is discussed and approaches being taken to identify the genes that may control flavivirus susceptibility in Ae.
336 citations