Search PubMed⌕ Search

Biomedical subjects

V Deubel

Publications and source records attributed to V Deubel.

90 records · Page 5Linked to original sources
PubMed1985

Homogeneity among Senegalese strains of yellow fever virus.

A series of 16 yellow fever (YF) viruses isolated from mosquitoes, monkeys and humans in different epidemiological contexts in Senegal and The Gambia between 1976 and 1983, was analyzed by T1 RNase oligonucleotide fingerprints of the genomic 32P-labeled RNA, by SDS-polyacrylamide gel electrophoresis of the intracellular virus-specified polypeptides, by peptide mapping of the envelope E glycoprotein and by immunological reactivities with monoclonal antibody fluids (MAF's) against the E glycoprotein. These strains had not been passed in suckling mice and were isolated in Aedes pseudoscutellaris Mos 61 cultured cells. These strains showed no virulence in three-week-old Swiss mice when injected intraperitoneally. Direct comparison of the large T1 RNase-resistant oligonucleotide maps indicated a relative genetic stability (92%-100%). A greater change was observed when these strains were compared with an epidemic YF strain isolated in 1965 with an oligonucleotide fingerprint map sharing 82%-88% similarity. The YF-specified proteins were identical in their molecular weight, and the fragments obtained after limited proteolysis of the envelope protein using protease V8 or alphachymotrypsine indicated that the strains were chemically similar. Only a few differences were observed when the strains were seroneutralized with MAF's, but no relation could be made with genetic or biological data. This suggested that the YF virus strains isolated from the same geographic area and during a short period of time had evolved slowly. Moreover, all the viruses were closely related and no correlation could be established with the apparent variations in virulence in nature.

Aedes↗
PubMed1983

Comparison of the enzyme-linked immunosorbent assay (ELISA) with standard tests used to detect yellow fever virus antibodies.

The enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies to yellow fever virus in 110 sera from patients living in an epidemic yellow fever area. The results were then compared with those obtained with the hemagglutination-inhibition (HI), complement-fixation (CF), neutralization (NT), and indirect immunofluorescence (IFA) tests. This ELISA, which used a type-specific antigen, showed the same results as the NT test and was found to be more sensitive and more specific than the HI and CF tests.

Antibodies, Viral↗
PubMed1981

Morphogenesis of yellow fever virus in Aedes aegypti cultured cells. I. Isolation of different cellular clones and the study of their susceptibility to infection with the virus.

We report the isolation of 19 cellular clones of Aedes aegypti and analyze their susceptibility to infection with yellow fever virus, in comparison with the uncloned cells. Four types of clones were found, different in their morphology, their metabolism and their virus production. The C 17 clone produces the most virus, not only with respect to the other Aedes aegypti clones, but also to other uncloned arthropod cells published in the literature. A cytopathic effect exists in the virus infected cells. Cloned and uncloned cells do not seem to produce any antiviral substance which transfers to other cells an immunity against the virus. An immunological study with immunoperoxidase enabled us to follow the appearance of viral antigens and to locate them in the cell. At the beginning we observed a perinuclear coloration diffusing further into the whole cytoplasm. The present report represents an introduction to a structural study on the morphogenesis of yellow fever virus within the cells of Aedes aegypti.

Aedes↗
PubMed1981

Morphogenesis of yellow fever virus in Aedes aegypti cultured cells. II. An ultrastructural study.

The growth and intracytoplasmic development of two yellow fever virus strains (wild and French neurotropic) were studied in Aedes aegypti cells (clone C 17). Despite a longer period of latency for the vaccine virus, infected cells appeared similar. The cisternae of the rough endoplasmic reticulum (RER) were swollen and formed vesicles which contained the virus. This RER appeared to be the predominant locus of viral synthesis and maturation. Cytopathic effect appeared when the cells were filled with vesicles, and it was characterized by cell degeneration and lysis.

Aedes↗
PubMed1977

[Irradiated cell cultures applied to group A "chlamydiae" isolation (author's transl)].

The irradiated Mc Coy cell cultures method modified by Darougar et al. has been used to investigate the frequency of Chlamydiae in non-specific genital tract disease, in Reiter's disease and in patients suffering from conjonctivits associated with non-specific urethritis. Isolates were obtained from 104 men of the 660 suffering from acute urethritis, and from 18 men of the 67 suffering from conjonctivitis associated with urethritis. Fourteen female sexual contacts of these men were tested: Chlamydiae was isolated from 9. Seven patients suffering from acute Reiter's disease were tested: Chlamydiae was isolated from 4. These patients were tested by complement fixation and titers of 1/8 or more were only obtained in the 4 isolated positive cases, the three other cases remaining negative. Isolates of Chlamydiae were obtained from 10 women of the 67 women suffering from exocervicitis. No isolate was obtained, from 27 control patients.

Arthritis, Reactive↗
PubMedDate not supplied

Comparative analysis of West Nile virus strains isolated from human and animal hosts using monoclonal antibodies and cDNA restriction digest profiles.

Three West Nile (WN) virus strains isolated in Bangui, Central African Republic (CAR), from patients with hepatitis were analysed comparatively with the prototype WN virus strain and 7 WN strains previously isolated from birds (2 strains), mosquitoes (3 strains) and ticks (2 strains) in CAR. The comparison was based on two techniques: an epitopic analysis by indirect immunofluorescence assay using a panel of 9 monoclonal antibodies to WN virus, and an analysis of HaeIII and TaqI restriction digest profiles of cDNA to infected cell RNA. Similar results were obtained with both techniques: the 3 human strains were found to be identical to each other and identical or very close to mosquito and tick strains, whereas prototype WN virus and bird strains were significantly different from the human strains. As "classical" infections due to WN virus without hepatic involvement were also reported during the period of isolation of the arthropod strains, we concluded that the same virus subtype may have been the cause of different infection patterns. A new definition of the disease spectrum of WN virus, including the possibility of liver involvement, should be established. Clearly, the Egyptian prototype WN virus represents a different topotype. Bird strains also appear to be different from human and arthropod strains, raising the question of their transmissibility and pathogenicity for man, and of the role of birds in the natural cycle of WN virus.

Animals↗
PubMedDate not supplied

Identification of mosquito-borne flavivirus sequences using universal primers and reverse transcription/polymerase chain reaction.

A reverse transcription/polymerase chain reaction (RT/PCR) protocol for the rapid detection and identification of flaviviruses was developed using a set of universal oligonucleotide primers. These primers correspond to sequences in the 3' non-coding region and in the NS5 gene which are highly conserved among the mosquito-borne flaviviruses. The sequences of the resulting amplified products were analysed for dengue 1, dengue 2, dengue 3, dengue 4, Japanese encephalitis, West Nile, yellow fever and Zika viruses, and compared with the published sequences of other flaviviruses. The 291-297 nucleotides corresponding to the C-terminus of NS5 gene showed 56 to 76% similarity, whereas the 3' non-coding region (190 to 421 nucleotides) showed only 20 to 36% similarity. Genetic classification of the Zika virus supported its traditional serological grouping. Recombinant plasmids containing the flavivirus sequences were used in a nucleic acid hybridization test to identify the RT/PCR products derived from viral RNA extracted from experimentally infected mosquitoes. The plasmids were dotted on a strip of nitrocellulose membrane and incubated with the RT/PCR product labelled with digoxigenin during the PCR step. This is a valuable method for the rapid and specific identification of mosquito-borne flaviviruses in biological specimens and for subsequent sequence analysis.

Animals↗
PubMedDate not supplied

Dengue encephalitis in French Guiana.

Thousands of cases of dengue fever (DF) and several cases of dengue haemorrhagic fever were recorded in French Guiana during the recent outbreak of dengue-2 virus (1991-1992) and in subsequent years. One case with clinical signs typical of classical DF with neurological complications is reported in this study. The neurological features (encephalitis) appeared during the acute phase, 2 days after the onset of fever. Dengue-2 virus was detected in both the cerebrospinal fluid and blood sample. This case was fatal. This first reported case of classical DF with encephalitis in French Guiana is a new demonstration of the potential neurovirulence of dengue viruses.

Aedes↗
PubMedDate not supplied

First case of yellow fever in French Guiana since 1902.

The first case of yellow fever in French Guiana since 1902 was reported in March 1998. The yellow fever virus genome was detected in postmortem liver biopsies by seminested polymerase chain reaction. Sequence analysis showed that this strain was most closely related to strains from Brazil and Ecuador.

DNA, Viral↗
PubMedDate not supplied

The relationships between West Nile and Kunjin viruses.

Until recently, West Nile (WN) and Kunjin (KUN) viruses were classified as distinct types in the Flavivirus genus. However, genetic and antigenic studies on isolates of these two viruses indicate that the relationship between them is more complex. To better define this relationship, we performed sequence analyses on 32 isolates of KUN virus and 28 isolates of WN virus from different geographic areas, including a WN isolate from the recent outbreak in New York. Sequence comparisons showed that the KUN virus isolates from Australia were tightly grouped but that the WN virus isolates exhibited substantial divergence and could be differentiated into four distinct groups. KUN virus isolates from Australia were antigenically homologous and distinct from the WN isolates and a Malaysian KUN virus. Our results suggest that KUN and WN viruses comprise a group of closely related viruses that can be differentiated into subgroups on the basis of genetic and antigenic analyses.

Aedes↗
PubMedDate not supplied

[Sylvatic yellow fever in Africa recent advances and present approach (author's transl)].

Recent works carried out in west and central Africa resulted in numerous yellow fever virus isolations from sylvatic mosquitoes in the forest-savanna transitional zone. This virus was also obtained from monkeys, whereas studies on sequence and duration of the observed epizootics permitted a previsional approach of the yellow fever mechanisms in the same belt, the epidemiological importance of which was stressed ("emergence zone"). In the same course of research and publications, the prevalent part of the involved mosquitoes as virus-reservoirs was constantly emphasized ("reservoir-vector"). Recent investigations on transovarial transmission and yellow fever isolations from male mosquitoes caught in the field, provide decisive support to such a conception. It can explain that epizootics may be locally observed several years in succession, despite the fact that yellow fever virus circulation seems to be fundamentally of a dynamic character. Yellow fever virus was recently obtained from ticks and tick-eggs.

Africa↗
PubMedDate not supplied

[Apoptotic cell death in response to dengue virus infection: what are the consequences of viral pathogenesis?].

Dengue is a human disease of viral etiology which may be fatal in its hemorragic form. It is widely spread in the tropical areas of the different continents and has been dramatically expanding over the past 30 years. Although an immunological disorder is thought to be involved in dengue physiological symptoms, the pathogenesis of dengue hemorragic fever has not yet been elucidated. Whether the immune response is deleterious or beneficial to the host remains a matter of debate. Other factors, related to virus replication in specific host cells, could also contribute to the severity of the disease. Apoptotic cell death is one of the important consequences of dengue virus infection both in vitro and in vivo. Dengue replication triggers apoptotic signals in neurons and hepatocytes although the original effectors and kinetics differ. Implications of the ongoing apoptotic processes in viral pathogenesis will be further discussed.

Animals↗