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At least 1,603 records · Page 89Linked to original sources
PubMed2006

Tsetse fly saliva biases the immune response to Th2 and induces anti-vector antibodies that are a useful tool for exposure assessment.

Tsetse flies (Glossina sp.) are blood-feeding dipteran insects that transmit African trypanosomes, parasites that are responsible for human sleeping sickness and veterinary infections. Increasing attention is being paid to the effects of tsetse fly saliva deposited at the feeding site, which enables the blood-feeding process and putatively promotes parasite transmission. Here we demonstrate that saliva induces strong humoral responses against the major 43-45 kDa protein fraction (tsetse salivary gland proteins 1 and 2 - Tsal1 and Tsal2) in mice and humans and suppresses murine T and B cell responses to heterologous antigen. The saliva-induced immune response is associated with a Th2-biased cytokine profile and the production of mainly IgG1 and IgE antibody isotypes. Functionally, the antibodies raised in mice exposed to tsetse fly bites or induced after experimental saliva immunisation do not affect the fly's blood-feeding efficiency nor its survival. We propose that anti-saliva as well as anti-Tsal1/2 antibody responses can be used in epidemiological studies as a tool to analyze human exposure to tsetse flies.

Animals↗
PubMed2003

Isolation and characterization of a novel insect defensin from Rhodnius prolixus, a vector of Chagas disease.

An antimicrobial peptide belonging to the defensin family of small cationic peptides associated with innate immunity in insects was isolated from the hemolymph of Rhodnius prolixus, a vector of Chagas disease. This peptide, designated R. prolixus defensin A, was purified and sequenced. The active peptide contains 43 residues and aligns well with other insect defensins. However the pre-pro region of the sequence has little shared identity with other insect defensins. We have identified 3 isoforms of R. prolixus defensin from cDNA clones obtained from RNA isolated from the whole bodies of immune activated insects. Northern analysis and Real-Time Quantitative PCR indicate that there is a very low baseline transcription of this peptide in naïve insects, and that transcription increases significantly in the fat body of immune activated insects. In addition there is a delayed induction of transcription of this peptide in the intestine 24 h post activation suggesting that the midgut/intestine of this species is active in the immune response against pathogens.

Amino Acid Sequence↗
PubMed2004

Evaluation of baculovirus expression vectors with enhanced stability in continuous cascaded insect-cell bioreactors.

Continuous protein production with baculovirus expression vectors in insect-cell bioreactors is characterized by a dramatic drop in heterologous protein production within a few weeks. This is mainly due to the spontaneous deletion of the heterologous gene(s) from the baculovirus genome and/or to the rapid accumulation of defective interfering baculoviruses (DIs). Cell culture experiments with bacmid-derived baculoviruses showed that spontaneous deletions in the foreign bacterial artificial chromosome (BAC) sequences readily occurred. These deletions correlated with a low density of baculovirus homologous (repeat) regions (hrs), which are located dispersed throughout the baculovirus genome and are believed to act as origins of viral DNA replication (oris). To test the hypothesis that deletions are more likely to occur in regions with a low ori density, the properties of bacmid-derived baculoviruses with an additional hr in the unstable BAC sequences were compared to the standard bacmid-derived baculovirus in a continuous cascaded insect-cell bioreactor configuration. All viruses were equipped with a green fluorescent protein (GFP) gene and a gene encoding the classical swine fever virus E2 glycoprotein (CSFV-E2). The insertion of an extra hr in the BAC vector led to improved genetic stability of adjacent sequences, resulting in prolonged protein expression. The maintenance of the BAC sequences appeared to be dependent on the orientation of the inserted hr. The advantages of the utilization of hrs to improve the stability of baculovirus expression vectors for the large-scale protein production in insect-cell bioreactors are discussed.

Animals↗
PubMed2004

The sandflies (Diptera: Psychodidae) in the Turkish province of Hatay: some possible vectors of the parasites causing human cutaneous leishmaniasis.

The province of Hatay, which lies on the Mediterranean coast in south-eastern Turkey, forms an important endemic area for human cutaneous leishmaniasis (HCL). Between the June and November of 2001, the sandflies in eight areas of the province, Erzin, Dortyol, Iskenderun, Kirikhan, Antakya, Samandag, Altinozu and Yayladagi, were surveyed, using sticky-paper traps placed in goat, sheep, cow or chicken sheds close to houses. Although 217 of the 998 sandflies caught belonged to the genus Sergentomyia, the rest were of Phlebotomus species, including some species that, elsewhere, are known to act as vectors of the parasites causing HCL. The Sergentomyia caught were either S. theodori (59.9%) or S. dentata (40.1%). Most of the Phlebotomus were P. sergenti (60.8%) but P. papatasi (18.8%), P. syriacus (9.3%), P. neglectus (5.1%), P. tobbi (2.7%), P. simici (2.2%), P. alexandri (0.9%) and P. kyreniae (0.1%) were also identified (the latter three species for the first time in Hatay province). The identification of the main vector species of sandfly in the province is complicated because it is still uncertain which Leishmania species cause(s) the local HCL. It seems likely, however, that P. sergenti is the main vector in Antakya, Iskenderun, Dortyol, Erzin and Kirikhan. In areas such as Altinozu and Yayladagi, where, although P. sergenti is very rare or absent, HCL cases still occur each year, other species, such as the relatively abundant P. papatasi and P. syriacus, may be the main vectors.

Animals↗
PubMed2005

Spectral sensitivity of the photonegative reaction of the blood-sucking bug Triatoma infestans (Heteroptera: Reduviidae).

We studied the spectral sensitivity of the visual system of the blood-sucking bug Triatoma infestans, one of the main vectors of Chagas Disease in South America. We quantified the photonegative reaction of this insect in a rectangular arena, half of which was kept dark and the other half illuminated with various intensities of different monochromatic lights (or broadband stimuli for lambda>665 nm). As a behavioral parameter of the photonegative response, we measured the time each insect spent in the dark half of the arena. We found that low intensity levels (under 0.06 microW/cm(2)) of monochromatic lights of 397, 458, 499, and 555 nm evoked a statistically significant (i.e., different from that of control groups) photonegative reaction. Insects were less sensitive to monochromatic lights of 357 nm (UV) and 621 nm (dark orange), and to broadband stimuli in the red part of the spectrum (665-695 nm). These findings indicate that the visual system of T. infestans is sensitive to broader regions of the spectrum than those previously reported.

Animals↗
PubMedDate not supplied

Estimation of malaria transmission from humans to mosquitoes in two neighbouring villages in south Cameroon: evaluation and comparison of several indices.

Malaria transmission from humans to mosquitoes was assessed in two neighbouring villages in a rural area near Yaoundé, Cameroon during high and low transmission seasons during 1998-2000, using several indices previously evaluated in different areas endemic for malaria but never directly compared. These indices were estimated from human parasitological data and mosquito infection rates and, for each individual, thick blood films were prepared at the same time as experimental infection of laboratory-bred mosquitoes. Among the 685 volunteers examined, the prevalence of Plasmodium falciparum gametocyte carriers was 16%, and 8% of individuals were able to infect mosquitoes. The percentage of mosquitoes that became infected by feeding on the infectious individuals was 21%. Children aged < 10 years contributed to about 75% of the infectious reservoir, although they constituted only 35% of the total population. Differences were found between the transmission seasons and the villages, and varied according to the index examined. Although there were more infectious individuals in one of the two villages, they were less infectious than those in the other village during the high transmission season. Comparative analysis of the transmission indices suggests the existence of functioning transmission-blocking immunity in one of the villages, which until now has been only hypothetically considered to play a role in malaria transmission in a natural setting. The epidemiological value of all the indices used and their accuracy in estimating the human infectious reservoir and its natural or induced variations are discussed.

Adolescent↗
PubMed1982

Antigenic relationships of flaviviruses with undetermined arthropod-borne status.

In contrast to most of the arthropod-borne flaviviruses, the flaviviruses with undetermined arthropod-borne status are probably disseminated only by direct contact with excreta (saliva, urine, feces, etc.); however, as yet undescribed arthropod transmission cycles may be found for some of them. Twenty-two of these flaviviruses, including prototype and recently isolated strains, were compared. Biologic properties were defined by infectivity titrations in suckling mice and Vero, LLC-MK2, and primary Pekin duck embryo cells, and antigenic relationships were defined by complement-fixation and plaque reduction neutralization tests. An antigenic classification scheme is proposed. Antigenic and biologic properties delimit two large clusters. The first, comprising a single antigenic complex, includes those which have yet to be isolated from arthropods, but are likely to be so (Israel turkey meningoencephalitis, Koutango, Negishi and Aroa viruses). The second, encompassing five antigenic complexes, is comprised of viruses which have been isolated exclusively from rodents or bats (Saboya, Carey Island, Dakar bat, Sokuluk, Bukalasa bat, Entebbe bat, Phnom Penh bat, Modoc, Sal Vieja, Jutiapa, San Perlita, Cowbone Ridge, Rio Bravo, Apoi, Tamana bat and Montana Myotis leucoencephalitis viruses) but includes three viruses (Saboya, Sokuluk and Entebbe bat viruses) which may be arthropod-borne, as indicated by replication in mosquito cells in vitro.

Aedes↗
PubMed1959

Aspects of black-fly control and entomology in the New World in relation to the Simulium problem in Nigeria.

A general account is given of insecticidal control of black-flies in North and Central America, and the problems are contrasted with those arising in the control of Simulium damnosum Theo. in Nigeria. Some recent biological observations on Canadian black-flies are described, and it is emphasized that these have materially contributed to successful control. It is pointed out that S. damnosum control is being practised in the absence of much fundamental biological knowledge of this pest. Entomological aspects of onchocerciasis in Mexico and Guatemala are discussed, and compared with S. damnosum and its relationship to onchocerciasis in Nigeria.

Animals↗
PubMed2003

Integrated vector management guidelines for adult mosquitoes.

A written document was developed to clarify the District's adult mosquito-management tactics to other interested individuals and agencies. The program described consists of 7 discrete components: 1) initiation criteria, 2) treatment area delineation, 3) agricultural and land-use practices, 4) meteorological conditions, 5) continuance criteria, 6) termination criteria, and 7) factors influencing implementation. The guidelines were adopted as policy by the District's Board of Trustees in 1998 and have been implemented in each of the last 5 years. The adult mosquito population is monitored with 6 Mosquito Magnets traps strategically located in the rice culture areas. Samples are collected daily and laboratory technicians notify the Adulticide/Airplane Coordinator of collection results before 1:00 p.m.

Agriculture↗
PubMed1991

[Experimental studies on the transmission of hemorrhagic fever with renal syndrome virus by gamasidea mites and fleas].

Hemorrhagic fever with renal syndrome (HFRS) virus was isolated from 3 species of gamasidea mites (Haemolaelaps glasgowi, Laelaps jettmari, Eulaelaps shanghaiensis), and 2 species of fleas (Monopsyllus anisus, Leptopsylla segnis) collected from nests of HFRS virus-infected Apodemus agrarius, whereas HFRS virus was not recovered from Gamasidea mites and fleas collected from nests of uninfected Apodemus agrarius. It was thus confirmed that HFRS is a disease of animal origin with natural foci of infection. Experimental studies demonstrated that positive results of virus isolation were obtained from originally healthy population of Monopsylla anisus, Leptopsylla segnis and Haemolaelaps glasgowi 24-48 hours after they had sucked HFRS virus suspension, while positive results of virus isolation were still obtained from Haemolaelaps glasgowi but not from 2 species of fleas 7 days after they had sucked HFRS sirus suspension. It was confirmed that Monopsylla anisus and Leptopsylla segnis cannot propagate HFRS, and therefore their transmission would be mechanical. On the contrary, Haemolaelaps glasgowi might play the role of biological vector.

Animals↗