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Biomedical subjects

C Hannoun

Publications and source records attributed to C Hannoun.

At least 109 records · Page 6Linked to original sources
PubMed1978

Biochemical evidence that "new" influenza virus strains in nature may arise by recombination (reassortment).

Oligonucleotide analysis of two avian influenza A viruses (Hav6N2 and Hav6Nav4) isolated in nature showed identical or almost identical patterns for the corresponding M and HA genes; 24 of 25 and 13 of 13 large oligonucleotides were indistinguishable by two-dimensional gel analysis. On the other hand, remarkable differences in the oligonucleotide patterns of the remaining genes were observed. Only 2 of 11 oligonucleotide spots of the NS gene, 10 of 27 spots of the NA/NP genes, and 22 of 49 spots of the P genes were indistinguishable between the two strains. On the basis of this observation that at least two genes of these viruses are virtually identical whereas others show easily detectable differences, we conclude that the two avian strains are related to each other by a recombinational event. In addition, it was found that animals in nature can be doubly infected with influenza viruses. Both lines of evidence strongly suggest that recombination is at least one mechanism by which "new" influenza virus strains emerge in nature.

Genes, Viral↗
PubMed1978

Togaviridae.

The family Togaviridae is described; it contains four genera--Alphavirus, Flavivirus, Pestivirus and Rubivirus--and additional members. The main characteristics of the family are as follows: single-stranded, linear RNA, molecular weight about 4 X 10(6). Virions have isometric nucleocapsids surrounded by a lipoprotein envelope containing host cell lipid and virus-specified polypeptides including one or more glycopeptides. Virions yield infectious RNA. There are at least 80 members; all the alphaviruses and most flaviviruses are arboviruses in the biological sense.

Arboviruses↗
PubMed1977

Immune responses to influenza virus in rabbits after local immunization. i.--Local and systemic humoral response.

IgA was found to be the predominant immunoglobulin in the bronchoalveolar secretions of rabbits. Significant quantities of IgG antibodies were also present in these secretions after intratracheal immunization with live influenza virus, but IgA/IgG ratios in the secretions were always higher than in corresponding sera, whether the rabbits were immunized or not. The relative excretion coefficients of IgA in these secretions were also found to be higher. In vitro culture of broncho-alveolar wash cells showed active synthesis of all the three major immunoglobulins with IgG as the predominant one. Immunization with live influenza virus induced a higher and more persistant antibody response in the respiratory secretions than the inactivated virus. A rapid and more intense production of IgA and IgG antibodies in these secretions after intratracheal booster antigen strongly suggests the presence of immunological memory in the secretory immune system of the respiratory tract. The role of secretory antiviral antibodies in protection against respiratory infections is also discussed.

Animals↗
PubMed1977

Potentiation of the immune response to influenza virus subunit vaccines.

Influenza subunit vaccines are poorly immunogenic in unprimed lower animals and man and methods were sought to potentiate the humoral response. Influenza B intact virus vaccines potentiated the antibody response of hamsters to purified vaccines containing influenza A hemagglutinin and neuraminidase subunits. The levels of anitbody induced were at least as high as those induced by equivalent doses of whole virus. Similarly, intact heterologous influenza A virus vaccine (A/Victoria/3/75 [H3N2]) potentiated the antibody response of hamsters to A/NJ/76 [Hswl NI] subunit vaccines but large doses of intact virus were required. Considerably lower doses of homologous intact A/NJ/76 [Hswl NI] potentiated the antibody response of hamsters and sero-negative people to subunit vaccines. This suggests that future influenza subunit vaccines for use in seronegative people should contain a minimal dose of whole virus vaccine sufficient to potentiate the immune response to the subunits but insufficient to be reactogenic. A synthetic water soluble adjuvant (N-acetyl-muramyl-L-alanyl-D-isoglutamine) was also shown to potentiate the immune response of hamsters to A/NJ/76 [Hswl NI] influenza virus subunit vaccines.

Adjuvants, Immunologic↗
PubMed1977

Immune responses to influenza virus in rabbits after local immunization. II. Local and systemic cell mediated response.

The development of local and systemic cell mediated immunity (CMI) was investigated in rabbits after intratracheal immunization with live or inactivated influenza A virus. Lymphocytes from bronchoalveolar washings and draining lymph nodes were used for the assay of local CMI response. Spleen cells were employed for determination of systemic responses. Since alveolar macrophages were found to be susceptible to the action of migration inhibiting factor, the development of CMI in lungs was assayed by macrophage migration inhibition test using bronchoalveolar was cells. Immunization with live virus induces beter local CMI response than inactivated virus. After primary immunization the peak responses were found between second and third week. The secondary response was detectable much earlier and peaked at one week after booster. Small amounts of inactivates virus, which was unsufficient to evoke a primary response, could elicit a strong secondary response. The development of rapid and accentuated secondary response in the local lymphoid tissues suggests the presence of memory in the local CMI response. The results also show a good correlation to exist between primary local CMI response and the skin reactivity to the immunizing antigen. However, lack of such correlation during the secondary response leaves the skin tests less reliable in the evaluation of CMI in viral infections. Some of the functions of alveolar macrophages in the local immune reponses are also discussed.

Animals↗
PubMed1976

[Influenza].

Explore the source record for details and available documents.

Humans↗
PubMed1976

Epidemiologic study of arboviruses in the Arba-Minch district of Ethiopia.

A yellow fever outbreak occurred in 1966 in Arba-Minch District, east of Abaya Lake, in Ethiopia. The present study was undertaken to assess the southern limits of that epidemic and to contribute to the inventory of arboviruses and potential vectors in that area. In the highlands 90 sera were collected, in the lowlands 140. With regard to Group B the sera reacted only with yellow fever, Wesselsbron and Spondweni antigens. In the highlands 17.8%, in the lowlands 22.2%, were positive for group B. In two sera only the titers against yellow fever were high. The absence of reactivity to West Nile virus was striking. A wide variety of Culicidae was present and differentiated. Potential or proven vectors were collected. At the time of the survey yellow fever was not active in the region. Because of an only partly immune human population, and of the presence of non-immune monkeys and some potential vectors, the area should, however, be considered to be receptive.

Animals↗
PubMed1975

[RNA polymerase activity associated with a bunya virus (Lumbo)].

RNA dependent RNA polymerase has been demonstrated in purified Lumbo virus (Bunyavirus) which contains a single stranded segmented RNA. Divalent cations (Mn++ and Mg++) are required for optimal in vitro activity. Reaction products can be specifically annealed with the viral genome.

Arboviruses↗
PubMed1975

Influenza virus and ciliary beating of the respiratory epithelium in sensitized animals.

Normally, under good survival conditions, the ciliary beating can be observed and recorded during hours after dissection of the respiratory epithelium. When laboratory animals have been immunized locally against influenza virus (under delayed type hypersensitivity conditions) the ciliary beating stops within 3 to 6 minutes when the same virus is put in contact with the sensitized mucosa. The specificity and the immunological conditions of this stopping have been analyed and the practical importance of this new test in cellular immunology is discussed.

Animals↗
PubMed1975

A sero-epidemiologic survey on arbovirus in Wuvulu Island.

The authors present here the results of a serological survey on arbovirus infections, which was conducted on 116 out of 505 inhibitants of Wuvulu island, the westernmost island of the Bismarck archipelago, located 260 km north of Wewak, Papua-New Guinea. The islanders are divided in two communities of unequal size: the Wuvulian themselves, who are Micronesians, and the coconut workers who are Melanesians coming from the Sepik district. In addition to the presence of a group A virus, this survey shows a recent infection in the Melanesians by Dengue type 2 virus, probably during the 1971-72 epidemic. The virus did not reach Wuvulu island, as shown by negative results observed in the micronesian sera. A better knowledge of the potential dengue mosquito vectors would be useful in order to define the risk of an eventual introduction of the virus on the remote island.

Arbovirus Infections↗
PubMed1975

An epidemiologic and serologic study of arboviruses in Lake Rudolf basin.

An epidemiologic and serologic study of arboviruses was done in 1972 in the basin of Lake Rudolf. The main object of this study was to demarcate the southern limit of the yellow fever epidemic which occurred from 1959 to 1962 in Southern Sudan and Ethiopia. Other purposes were to contribute to the inventory of arboviruses and their distribution in this region. The ethnic groups were studied: the Nyangatom and the Dassanetch in Ethiopia and the Turkana in northern Kenya. The results of tests on sera of the Nyangatom and the Dassanetch are practically identical: a high percentage of positive tests for group B. The Turkana on the other hand show a low percentage of positives. This is attributed to differences in the climatic characteristics of the two regions. The serological results suggest the presence of West Nile virus in the geographical areas inhabited by the three ethnic groups. The presence of Wesselsbron and probably Uganda S virus is suspected. Circulation of these viruses could be explained by the presence of Culex univittatus and other mosquitoes. As for yellow fever, the results suggest that the virus did not reach the areas studied, probably because of absence of efficient vectors.

Antibodies, Viral↗
PubMed1975

Cellular aspects of local antibody response in rabbits.

Live or inactivated influenza virus is inoculated intratracheally to rabbit. After 4 days or more, lungs are washed with 50 ml of saline and fluid is examined for immunoglobulin and antibody content as well as for type and properties of free cells. IgA and IgG are detectable in the fluid but not IgM. Specific antiviral activity is associated only with IgA at the earliest stages. Free cells are so called 'alveolar macrophages' as demonstrated by shape and phagocytic or enzymatic properties. Their total numbers vary according to type of immunization: non-immunized 5.10-5. inactivated virus 2.10-6. live virus 10.10-6. A high percentage (50 to 90 percent) are positive in IgA IF test, only 10 percent with IgG test. Peroxydase electron microscopy shows intracellular presence of IgA.

Acid Phosphatase↗