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Biomedical subjects

C Hannoun

Publications and source records attributed to C Hannoun.

At least 73 records · Page 4Linked to original sources
PubMed1988

Virus enhances histamine release from human basophils.

Histamine release from human basophil leukocytes was triggered by Staph. aureus or by complement activation caused by endotoxins isolated from E. coli or Salmonella bacteria. Influenza A virus was found to enhance the mediator release and the effect was caused by synergism, since the virus itself did not release histamine. The potentiating effect of the virus was abolished by a potent neuraminidase inhibitor. Furthermore, a purified neuraminidase preparation obtained from Vibrio cholerae caused a similar potentiating effect, which was also abolished by the neuraminidase inhibitor. These findings indicate that the neuraminidase on the surface of influenza A virus is responsible for the potentiating effect of the virus on basophil histamine release.

Basophils↗
PubMed1988

Influenza A virus potentiates basophil histamine release caused by endotoxin-induced complement activation. Examination of normal individuals and patients with intrinsic asthma.

Histamine release from human basophil leukocytes was triggered by complement activation by means of endotoxins isolated from E. coli and Salmonella bacteria. Influenza A virus was found to enhance the mediator release, and the effect was caused by synergism, since virus itself did not release histamine. The potentiating effect was similar in cells from normal individuals and from patients with intrinsic asthma. The involvement of viral neuraminidase was examined by a potent neuraminidase inhibitor and this inhibitor completely abolished the potentiating effect by virus. A purified neuraminidase preparation obtained from Vibrio cholerae caused a similar potentiating effect in mediator release and the effect was abolished by the neuraminidase inhibitor. These findings indicate that viral neuraminidase is responsible for the potentiating effect of virus on the histamine release. This effect might play a role in septic conditions and possibly contribute to asthmatic attacks by infections.

Aged↗
PubMed1987

[Human arbovirus infections in Burundi: results of a seroepidemiologic survey, 1980-1982].

A serological survey on 623 human sera was conducted in Burundi in 1980-1982, in order to evaluate the frequency of arboviral antibodies in the inhabitants of the three main areas: lowlands, central plateau and mountainous ridge. The results show a rather high activity of arboviruses, mainly in the lowlands (34.2% of inhabitants with antibodies). Chikungunya virus seems to be the most active arbovirus; the activity of Flavivirus is moderate; no trace of activity of yellow fever or West Nile viruses was found; Bunyavirus antibodies (particularly against Ilesha virus) were also detected.

Alphavirus↗
PubMed1987

[Response to influenza vaccine in uremic patients: relation to erythrocyte magnesium and the value of a second injection].

Humoral response to influenza vaccination being variable in uremic patients and being negatively correlated to red blood cell magnesium (RBC Mg) in non-uremic subjects, RBC Mg as well as plasma concentration of Mg were measured simultaneously with the antibodies titers after 1 and 2 injections of influenza vaccine in 21 non-uremic subjects and 47 patients on chronic hemodialysis. The RBC Mg and plasma Mg (MgP) were significantly higher in the dialysed patients (74 +/- 12 mg/l; 25 +/- 8 mg/l) than in the non-uremic subjects (54 +/- 5 mg/l; 19.4 +/- 1.5 mg/l). Furthermore, in the uremics RBC Mg was correlated to PMg whereas such a correlation was absent in the non-uremic patients. The humoral response of the uremic patients is depressed and becomes comparable to that of the non-uremic subjects after 1 injection only after 2 injections. In the uremic patients, the depressed humoral response is associated with higher RBC Mg (greater than 70 mg/l). The humoral response to influenza vaccine is depressed in uremic patients who have either the HBs antigen or no response to the hepatitis B vaccine but no link has been found between this immune status against the hepatitis B and RBC Mg. In conclusion, the humoral response of the uremic patients to influenza vaccine is depressed so that a second injection is necessary to give them sufficient protection.

Adult↗
PubMed1986

[Evaluation of thermostable yellow fever vaccine from the Pasteur Institute on international travellers].

The authors studied the tolerance and efficacy of the new stabilized 17D yellow fever vaccine produced by Pasteur Vaccins, on 50 international travellers at the University Hospital of Grenoble (France), comparing it with the standard 17D yellow fever vaccine. The short-term and long-term tolerance in all the travellers was excellent. The serological efficacy was estimated by seroneutralization assay with the vaccine virus Rockefeller 17D, which is the most sensitive and the most specific method. The seroconversion rate was 93.8%, the same as the rate obtained with the standard yellow fever vaccine in 50 other travellers. The authors studied also the serological response to the standard yellow fever vaccine associated with other vaccines (diphtheria, tetanus, oral or injectable poliomyelitis, and oral cholera): the seroconversion rates were similar to those obtained with the yellow fever vaccine alone, thus demonstrating that these associated vaccines do not interfere with immunization against yellow fever.

Drug Tolerance↗
PubMed1986

Comparative clinical study of a new 17D thermostable yellow fever vaccine.

The immunogenicity and the safety of a new heat-stable 17D yellow fever vaccine have been assessed in a randomized comparative study by reference to a non-stabilized vaccine preparation. Seronegative adults were used and 115 and 143 were given the heat-stable and the non-stabilized vaccine, respectively. Fifty two days after the immunization, haemagglutination inhibiting antibodies were found in 77.6 and 73.9% of the vaccinees, neutralizing antibodies in 99.3 and 100% of them. The percentage of seroconversion and the geometric mean of antibody titres were not significantly different. No complaints or adverse reactions in association with the vaccines were recorded. This study demonstrates the high immunogenicity of this new stabilized vaccine whose stability has already been proven.

Adult↗
PubMed1986

Adherence of type I Streptococcus pneumoniae to tracheal epithelium of mice infected with influenza A/PR8 virus.

Bacterial adherence to virus-infected respiratory tract cells may be one of the several mechanisms whereby virus predisposes to bacterial pneumonia. To evaluate the effect of influenza virus infection on pneumococcus adhesion, 39 mice were infected with PR8/A influenza virus. The adherence of radiolabeled pneumococcus to mice tracheal cells was determined 2, 4, and 6 days after viral inoculation. The pneumococcal adhesion to infected tracheas was significantly enhanced on Day 6 (p less than 0.001). Scanning and transmission electron microscopy revealed that by the fourth and sixth days after virus inoculation, the ciliated and the secretory cells of the tracheal epithelium had desquamated and the mucosa were coated with a continuous layer of basal cells. In a few cases, a desquamation of the basal layer was observed and the exposed basement membrane appeared as a pole of attraction for bacteria. Pneumococci were never seen attached to control tracheas. In contrast, they were observed adhered to the microvilli of the basal cells and, to a greater extent, to the exposed basement membrane.

Animals↗
PubMed1985

Fine specificity analysis of human influenza-specific cloned cell lines.

Influenza-specific human-T-cell clones, proliferating in the presence of virus-infected cells with restriction by class II molecules and displaying class II-restricted CTL activity or specific helper activity in antibody synthesis, have been analyzed for antigenic specificities. All of them were obtained by in vitro stimulation against influenza A/Texas virus. In all cases the virus specificity appeared identical in cytolytic and proliferative responses. Three of the clones were broadly cross-reactive, recognizing all or almost all type A influenza strains. The three remaining clones were subtype specific when tested with human strains and recognized the surface glycoproteins of influenza virus. One of these lines reacted with an epitope of the neuraminidase N2 while the other two recognized the hemagglutinin H3. By using a large panel of mammalian and avian influenza strains, it can be demonstrated that hemagglutinin-specific human T cells can recognize a cross-reacting determinant shared by H3 and H4 subtypes of hemagglutinin which has never been detected with antibodies.

Animals↗
PubMed1985

Relationship between postvaccinal anti-influenza antibodies, blood magnesium levels, and HLA antigens.

Seventy-eight healthy subjects belonging to 16 different families were submitted to an anti-influenza vaccination. The antibody titers and the red blood cell and plasma Mg concentrations were determined before and 30 days after vaccination. The population study performed on 32 subjects showed the occurrence of a higher antibody response (P less than 0.01) and a lower red blood cell Mg level, among the Bw35 individuals. These findings are confirmed by family studies: HLA identical sibs have values much closer to those of the propositi than to those of the HLA different sibs. The relationships between HLA, immune response, and Mg revealed by the present investigation are discussed in light of the literature together with the known associations between HLA Bw35 antigen and diseases.

Adult↗
PubMed1985

Arboviruses and lemurs in Madagascar: experimental infection of Lemur fulvus with yellow fever and West Nile viruses.

In previous serological surveys of lemurs in Madagascar, antibodies against flaviviruses were frequently detected. To examine the epidemiological role of Lemur fulvus, experimental infections with yellow fever (YF) virus and West Nile (WN) virus were performed. YF and WN infections were clinically unapparent. A 3 to 4-day-long viremia, with moderate levels was observed with YF virus. WN virus, especially the strain isolated in Madagascar, provoked a 4 to 6-day-long viremia sufficient to infect Aedes aegypti. In all experiments, the antibody response was studied during the following weeks by 3 methods. The results led to the conclusion that Malagasy lemurs could act as amplifying hosts for WN virus present in Madagascar, and as hosts for YF virus if it were introduced on the island. The epidemiological role of these primates is discussed according to their ecology and their contact with potential mosquito vectors in forest areas of Madagascar.

Aedes↗
PubMed1984

Influenza A hemagglutinin-specific T cell clones strictly restricted by HLA-DR1 or HLA-DR7 molecules.

The antigenic specificities, major histocompatibility complex restrictions and functional properties of influenza virus-specific proliferative cloned cell lines have been studied. These lines were specific for the H3 hemagglutinin subtype of influenza A viruses. By using a large panel of HLA-phenotyped antigen-presenting cells, it was found that the polymorphic structures, defined as DR1 and DR7 molecules, or closely associated structures, function as the restricting elements. We excluded for these lines a possible restricting role of supertypic specificities, known cross-reacting elements on DR molecules, or products of other loci in known linkage disequilibrium with the HLA-DR molecules. Such exquisitely restricted clones might be of great help in the class II typing of antigen-presenting cells. Their specific activity was stable for several months. This has allowed the study of some functional properties of these long-term-cultured cloned cell lines: interleukin 2 sensitivity and production, helper function in specific antibody synthesis and ability to stimulate in mixed leukocyte reactions.

Adult↗
PubMed1984

Antigenic comparisons of swine-influenza-like H1N1 isolates from pigs, birds and humans: an international collaborative study.

The objective of this international collaborative study was to compare recent swine isolates of influenza viruses and determine whether significant antigenic differences among isolates from different areas of the world could be detected. H1N1 viruses isolated from pigs, birds and humans in 12 different countries were compared in haemagglutination-inhibition assays with post-infection ferret sera and monoclonal antibodies to H1N1 strains. Using A/NJ/8/76 as the reference strain, we found that recent swine isolates from Hong Kong, Italy, Japan, and the USA possess a haemagglutinin virtually indistinguishable from that of viruses typically associated with pigs, i.e., A/NJ/8/76. In contrast, recent swine isolates from several European countries (Belgium, Denmark, France, Federal Republic of Germany, and Spain) were distinguishable from A/NJ/8/76, as demonstrated by tests in the various laboratories. These studies suggest that the H1N1 viruses in pigs are antigenically heterogeneous and that the circulation of particular variants is associated with the geographical location of the animals. These results raise the question of whether these viruses originated from the same source, i.e., pigs, and have undergone antigenic drift or, alternatively, were introduced from other hosts, such as birds.

Animals↗
PubMed1983

Unusual restriction of a proliferative line reacting with influenza A and B viruses.

A human T-cell line, B3, has been obtained by cloning spleen cells at limiting dilutions in the presence of influenza-A-virus-infected autologous cells. B3 cells were OKT 3+4+8-, E rosetting+, Sig- and were HLA-DR (+) after stimulation and HLA-DR (-) when resting. They proliferate specifically in the presence of influenza-virus-infected cells. Remarkable is that (a) the proliferation was obtained with viruses of both A and B types and (b) only autologous cells seem to be able to present the viral antigen to B3 cells.

Antibodies, Monoclonal↗
PubMed1983

A fluorometric procedure for measuring the neuraminidase activity: its application to the determination of this activity in influenza and parainfluenza viruses.

A fluorometric procedure for quantitating the amount of N-acetylneuraminic acid enzymatically released by the neuraminidase activity from N-acetylneuraminyl-lactose (sialyl-lactose) has been developed. The liberated lactose is hydrolyzed with beta-galactosidase, and the released galactose is oxidized with galactose dehydrogenase and NAD+; finally, the NADH produced is measured by fluorometry (excitation at 340 nm and analysis of emitted light at 465 nm). The fluorometric assay is about 10-fold more sensitive than the spectrophotometric procedure that measures NADH at 340 nm. It readily measures amounts as little as 2 nmol of sialic acid, and does not require the use of radioactive isotopes. Interferences due to sucrose or other substances, which cause errors in some cases with the use of the periodate-thiobarbiturate method for neuraminidase activity determination, are avoided. The procedure reported here provides a sensitive, rapid, and relatively simple method (feasible with commercialized reagents) for measuring the neuraminidase activity not only in purified samples from different sources but also directly in biological materials such as viruses. The technique has been tested with some viruses recently isolated belonging to Orthomyxoviridae or Paramyxoviridae families, known to be rich in neuraminidase. Reciprocally, this method can also be employed for determining the sialic acid concentration in acylneuraminyl-lactose-containing compounds when using purified neuraminidase for hydrolysis.

Chemical Phenomena↗
PubMed1983

Genetic relatedness of hemagglutinins of the H1 subtype of influenza A viruses isolated from swine and birds.

The hemagglutinin (HA) gene of the influenza virus subtype H1N1 isolated from pigs and birds has been analyzed by the hybridization technique. According to the RNase protection data the HA genes of recent isolates from pigs in Northern Europe are genetically more closely related to those of isolates from birds in Europe and North America than to those of isolates from pigs in the United States, Taiwan, and Italy. Thus, two different H1N1 subtypes are circulating in the pig population. The results are consistent with the view that H1N1 viruses can be transmitted from birds to pigs and/or vice versa.

Animals↗
PubMed1983

[Blockade of the anti-influenza specific proliferative response of cloned cell lines restricted either by HLA-DR7 or HLA-DR1 molecules or by a still-unknown molecule].

Four different continuous cell lines of T lymphocytes are described, three of them were obtained by cloning. Their activity is restricted in three cases by a histocompatibility antigen undistinguishable from HLA-DR. The last one is restricted by an autologous unidentified structure. The first three lines are specific for a viral antigen corresponding to a subtype of the H3 hemagglutinin. The fourth line seems to react with an hitherto undescribed antigen shared by type A and type B influenza viruses.

Antibodies, Monoclonal↗
PubMed1983

Anti-influenza human T killer cells present an intertypic activity anti-A and -B type viruses in a secondary reaction in vitro.

In man influenza viruses induce a cytolytic T lymphocyte (CTL) activity directed against autologous or HLA-A or -B compatible target cells infected with the immunizing virus. While only type specific CTL are characterized in man, we report here experiments showing intertypic activities of human CTL from donors vaccinated with both A and B type influenza viruses. Their peripheral blood leucocytes (PBL) restimulated in vitro with live influenza virus of one type gave rise to both anti-A and -B activities, when non-infected or Sendaï infected target cells were not lysed. These intertypic activities were restricted by HLA-A or -B antigens and were inhibited by OKT3 antibody. When u.v.-inactivated viruses were used as restimulating antigen, no intertypic CTL were obtained. The results of competition experiments with cold targets show that no common antigens were recognized by anti-A and anti-B CTL. Moreover the restricting HLA-A or -B molecules seen in association with A or B types viruses appeared different in the same experiment, confirming that different antigens were probably involved for the agents of A and B subgroups. This influenza specific intertypic activity was therefore probably due to an intertypic stimulation of type specific CTL activities, possibly arising at the level of T helper cells.

Antigens, Viral↗