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At least 1,657 records · Page 92Linked to original sources
PubMed1990

Co-expression of the human HLA-B27 class I antigen and the E3/19K protein of adenovirus-2 in insect cells using a baculovirus vector.

We have expressed the human MHC class I HLA-B27 antigen, human beta 2-microglobulin, and the E3/19K protein of adenovirus-2 in Spodoptera frugiperda insect cells (Sf9) by using the Autographa californica nuclear polyhedrosis virus. All genes were inserted under the strong polyhedrin promoter in the vector pVL941. The proteins were expressed at high levels, ranging from 1 to 8 mg protein per 3 x 10(9) cells. Both a full-length and a truncated form of HLA-B27 were expressed. The latter was terminated at the border of the membrane-spanning segment at the extracellular side of the membrane. The HLA-B27 antigens and the E3/19K protein showed considerable heterogeneity with respect to glycosylation. Only a small fraction of HLA-B27 was assembled (less than 5%) with beta 2-microglobulin. Nevertheless, we were able to find the heavy chain at the cell surface, and by co-infection with the recombinant virus for beta 2-microglobulin we observed an increase in cell surface expression. The E3/19K protein of adenovirus-2 blocks cell surface expression of HLA class I antigens in human cells and has a similar effect in insect cells. In contrast to beta 2-microglobulin it assembles efficiently to the heavy HLA-B27 chain, both the full-length and truncated forms. The E3/19K protein does not stimulate assembly of HLA-B27-beta 2-microglobulin. Due to these problems of assembly and the heterogeneity of glycosylation we predict that it will be difficult to use HLA antigens produced in insect cells for X-ray crystallographic studies.

Adenovirus E3 Proteins↗
PubMed1989

Synthesis of immunogenic, but non-infectious, poliovirus particles in insect cells by a baculovirus expression vector.

A baculovirus expression vector (AcLeon) derived from Autographa californica nuclear polyhedrosis virus (AcNPV) was prepared containing the complete 6.6 kb coding region of the P3/Leon/37 strain of poliovirus type 3 placed under the control of the AcNPV polyhedrin promoter. The recombinant virus was used to infect Spodoptera frugiperda insect cells. As demonstrated by use of the appropriate antibodies, infected insect cells made poliovirus proteins that included the structural proteins VP0, VP1 and VP3. Poliovirus particles were recovered from extracts of the infected cells and demonstrated to be free from detectable levels of RNA and to be non-infectious in tissue culture. After particle purification by CsCl gradient centrifugation and immunization of outbred mice, antibodies to the structural proteins, including neutralizing antibodies, were obtained. Other recombinant baculoviruses, containing the majority of the capsid coding region of P3/Leon/37 (e.g. AcCAP21, nucleotide residues 742 to 3318), made an unprocessed precursor to the poliovirus structural proteins. These data suggested that processing of the poliovirus gene product by the AcLeon construct was catalysed by the poliovirus-encoded proteases. The results demonstrated that antigenic and immunogenic poliovirus proteins and empty particles can be made in insect cells by recombinant baculoviruses.

Animals↗
PubMed1990

Identification of bluetongue virus VP6 protein as a nucleic acid-binding protein and the localization of VP6 in virus-infected vertebrate cells.

Recently the insect baculovirus Autographa californica nuclear polyhedrosis virus (AcNPV) has been effectively adapted as a highly efficient vector in insect cells for the expression of various genes. A cDNA sequence of RNA segment 9 of bluetongue virus serotype 10 (BTV-10, an orbivirus member of the Reoviridae family) encoding a minor core protein (VP6) has been inserted into the BamHI site of the pAcYM1 transfer vector derived from AcNPV. Spodoptera frugiperda cells were cotransfected with the derived vector in the presence of authentic AcNPV DNA to produce recombinant viruses. These synthesized significant amounts of a protein (representing ca. 50% of the stained cellular protein) similar in size and antigenicity to the authentic BTV VP6. The expressed protein was identified as a nucleic acid-binding protein by using an RNA overlay-protein blot assay. A polyclonal anti-VP6 serum prepared by using the expressed VP6 protein has been used in an immunogold procedure to locate VP6 in BTV-infected mammalian cells. Gold was found to be associated with the matrix of virus inclusion bodies (VIB), with viruslike particles in the VIB, as well as with mature virion particles that were in close proximity to the VIB or were released from cells and adsorbed to cell surfaces. The recombinant virus antigen has also been used to identify antibodies to different BTV serotypes in infected sheep sera, indicating the potential of the expressed protein as a group-reactive antigen for the diagnosis of BTV infections.

Animals↗
PubMed2006

Density-dependent host choice by disease vectors: epidemiological implications of the ideal free distribution.

The proportion of vector blood meals taken on humans (the human blood index, h) appears as a squared term in classical expressions of the basic reproduction ratio (R(0)) for vector-borne infections. Consequently, R(0) varies non-linearly with h. Estimates of h, however, constitute mere snapshots of a parameter that is predicted, from evolutionary theory, to vary with vector and host abundance. We test this prediction using a population dynamics model of river blindness assuming that, before initiation of vector control or chemotherapy, recorded measures of vector density and human infection accurately represent endemic equilibrium. We obtain values of h that satisfy the condition that the effective reproduction ratio (R(e)) must equal 1 at equilibrium. Values of h thus obtained decrease with vector density, decrease with the vector:human ratio and make R(0) respond non-linearly rather than increase linearly with vector density. We conclude that if vectors are less able to obtain human blood meals as their density increases, antivectorial measures may not lead to proportional reductions in R(0) until very low vector levels are achieved. Density dependence in the contact rate of infectious diseases transmitted by insects may be an important non-linear process with implications for their epidemiology and control.

Animals↗
PubMed1999

Insecticide resistance in malaria vectors: a new approach to an old subject.

The application of biochemical and molecular biological techniques to the study of insecticide resistance has revolutionized our understanding of the underlying genetic basis of resistance. Using the examples of glutathione S-transferase and esterase-based metabolic insecticide resistance, three different routes via which increased insecticide detoxication can be achieved are elucidated. An understanding of these molecular pathways opens up new avenues for manipulating mosquito populations to restore insecticide susceptibility to the vectors.

Animals↗
PubMed2000

Why aircraft disinsection?

A serious problem is posed by the inadvertent transport of live mosquitoes aboard aircraft arriving from tropical countries where vector-borne diseases are endemic. Surveys at international airports have found many instances of live insects, particularly mosquitoes, aboard aircraft arriving from countries where malaria and arboviruses are endemic. In some instances mosquito species have been established in countries in which they have not previously been reported. A serious consequence of the transport of infected mosquitoes aboard aircraft has been the numerous cases of "airport malaria" reported from Europe, North America and elsewhere. There is an important on-going need for the disinsection of aircraft coming from airports in tropical disease endemic areas into nonendemic areas. The methods and materials available for use in aircraft disinsection and the WHO recommendations for their use are described.

Aircraft↗
PubMed2001

Structural biology and its applications to the health sciences.

Part of the decipherment of genomic information lies in understanding the structure and function of the protein products of these genes. Protein structure is of further importance because of the molecular basis of many diseases. Structural biology is the field of research focusing on the experimental determination of the structure of biological molecules. We review the field of structural biology and its application to medical research and drug discovery, and describe the structural results recently obtained in our laboratory for the detoxifying enzyme glutathione S-transferase from the Asian mosquito Anopheles dirus species B, an important malaria vector. These enzymes have detoxifying activity toward pesticides and thus contribute to pesticide resistance in insects.

Amino Acid Sequence↗
PubMedDate not supplied

Male and mosquito larvae survey at the Arenal-Tempisque irrigation project, Guanacaste, Costa Rica.

A monitoring of male and larvae of mosquitoes was conducted during 1991-1994, at the Irrigation Project in Arenal-Tempisque, Guanacaste, Costa Rica. CDC CO2-baited traps were used to collect adults of mosquitoes and dips were used for immatures of culicids. A total of 1,480 larvae and 1,129 males of culicids were identified resulting in, Aedes with 6 species, Anopheles, Mansonia and Psorophora with 2 species, Culex with 21 species and Haemagogus, Limatus, Toxorhynchites and Uranotaenia with only one species each. The results indicate that, as occurred in other countries, irrigation projects must be under strict monitoring programs to prevent and control possible health problems in which mosquitoes act as vectors.

Animals↗
PubMedDate not supplied

[Vector control and malaria control].

Vector control is an integral part of malaria control. Limiting parasite transmission vector control must be considered as one of the main preventive measure. Indeed it prevents transmission of Plasmodium from man to vector and from vector to man. But vector control must be adapted to local situation to be efficient and feasible. Targets of vector control can be larval and/or adults stages. In both cases 3 main methods are currently available: physical (source reduction), chemical (insecticides) and biological tolls. Antilarval control is useful only in some particular circumstances (unstable malaria, island, oasis...) Antiadult control is mainly based upon house-spraying while pyrethroid treated bed nets is advocated regarding efficiency, simple technique and cheap price. Vector control measures could seem restricted but can be very efficient if political will is added to a right choice of adapted measures, a good training of involved personal and a large information of the population concerned with vector control.

Africa↗
PubMed1989

[To explore the principal vector of malaria by using vectorial capacity].

This paper reported the vectorial capacity of various anopheles in a tertian malaria infectious area for the period of 1980-1982. The ecological data of various anopheles, which used to take the account into vectorial capacity, were collected in the same manner. We consider that whatever species of anopheles possessing the biggest vectorial capacity, should also be probably the principal vector in that area. 13 species of anopheles had been found in the investigation region but only four species could provide enough data to be involved in the vectorial capacity. The A. sinensis became the highest. Reviewing the monthly distribution, this species as vectorial capacity showed a positive correlation with malaria incidence rate. Therefore this is regarded as the principal vector in that area.

Animals↗
PubMed1978

Distribution and density of mosquitoes in two endemic areas for bancroftian filariasis in Sorsogon, Philippines.

Mosquito density in Rangas where abaca is in abundance is much higher, almost twice, than that of Putiao where abaca is absent. The adult density of Aedes poecilus over Aedes ananae in the two areas combined is 3 to 4 times whereas the larval density of the former is much lower than Aedes ananae. The banana axils is a favorite breeding place for Aedes poecilus but may also utilize the abaca axils. This finding is very favorable in the transmission of bancroftian filariasis because this species of banana is planted around houses even closer to human dwelling than the abaca plants. Aedes poecilus being more anthropophylic than zoophylic can be domesticated as Culex quinquefasciatus and Aedes aegypti which again is a factor in favor of ideal transmission of the disease. The fact that bananas are planted around houses both in villages and towns, transmission of the disease could easily occur in both places, which should be borne in mind when planning a control program. The number of dissected mosquitoes is too small to be of significance in vector determination.

Animals↗
PubMed1979

Vectors of dengue fever/dengue haemorrhagic fever with advances in their control.

The most important vector of dengue in the Western Pacific Region is Ae. aegypti. On some occasions, Ae. albopictus, Ae. polynesiensis and several other species of the Ae. scutellaris complex have been suspected vectors in localities where Ae. aegypti was not found. Long-term vector control by the use of insecticides has been expensive and difficult to achieve. However, spray equipment and ULV insecticides have been obtained in many places for emergency use during outbreaks, and Abate larviciding also has been used in high-risk localities to help prevent outbreaks. Obtaining greater community participation supported by intensified health education and other acceptable measures is considered an important approach for achieving improved long-term control. Developing an acceptable and effective cover for domestic water storage containers is also recognized as a potentially important tool for suppressing vector populations.

Aedes↗
PubMed1975

[The mechanism controlling the crossing of the vector's stomach wall by microfilariae (Dipetalonema dessetae-Aedes aegypti)].

In some of the human filariasis, the number of microfiliariae which succeed in crossing the vector's stomach wall is smaller when the number of ingested microfilariae is larger (limitation). In the couple Dipetalonema dessetae-Aedes aegypti, this phenomenon appears to be due to a specific lysis of the stomach cells invaded by the microfilariae. This reaction is started when the microfilariae are very numberous. There is "information" transmitted to the whole of the vector's stomach.

Aedes↗
PubMed2004

[Expression of human follicle stimulating hormone in insect cells].

To study the expression of hFSH in insect cells, the cDNA encoding the hFSH beta chain was cloned by overlapping-PCR using human chromosome DNA extracted from placental tissue as template. Then we constructed expression vector pVL1393/hFSH beta using an unfused protein nuclear polyhedrosis virus (AcNPV) expression vector. The insect cells (SF9) were cotransfected with the expression vector and nuclear polyhedrosis linearized virus DNA, and recombinant viruses AcNPV-hFSH beta were collected. The beta subunit of hFSH expressed in plasma of the SF9 cells was detected by Western blot analysis, and showed apparent molecular masses of 21 kDa. After coinfecting SF9 cells with recombinant viruses AcNPV-hFSH beta and AcNPV-hCG alpha, secreted heterodimer of hFSH was detected by Western blot under non-reducing conditions. The apparent molecular weight of heterodimer was about 33 kDa.

Animals↗
PubMed1988

Horse-baited insect trap and mobile insect sorting table used in a disease vector identification study.

A horse-baited trap and a mobile insect sorting table were used to conduct an arthropod survey for potential vectors of Potomac Horse Fever in southern Maryland and northern Virginia. The trap and table worked effectively for the live collection and sorting of haemophagous Diptera such as: Simulium spp., Stomoxys calcitrans, Musca autumnalis, Tabanus spp. and Chrysops spp. during the diurnal collections periods, and Culicoides spp. during the crepuscular periods. The trap was not as convenient for live collection of mosquito species during the nocturnal period. Modifications to the trap design was suggested for mosquito live trapping.

Animals↗
PubMed1995

Expression of a recombinant derivative of human aromatase P450 in insect cells utilizing the baculovirus vector system.

Aromatase P450 (P450arom) is the enzyme responsible for estrogen biosynthesis. Studies of the relationship of the function of this enzyme to its structure have been hampered by lack of a suitable preparation. In the present report we describe the expression of a recombinant derivative of P450arom in insect cells by means of the baculovirus vector system. This protein, which lacks the first 41 amino acids from the N-terminus, and hence the membrane-spanning region, has spectral properties and activity similar to that of the wildtype protein. Moreover, the presence of a hexameric histidine tag at the C-terminus permits its facile purification by means of nickel-agarose affinity chromatography. This system permits the synthesis of quantities of a biologically active derivative of P450arom suitable for studies designed to explore the relationship of function to structure.

Androstenedione↗