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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.

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.

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.

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.

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.

By combining a tissue culture method with the detection of antibody-producing cells by local hemolysis in gum it has been possible to follow the immunological activity of cells from tissue fragments for long period of time. These fragments were obtained from lymph nodes or spleens of rabbits immunized by sheep erythrocytes. It was found that, while the immunological activity of the free cells in suspensions decreased fast and disappeared in a few days, the cells attaching on glass could express their activity for at least 3 wk. It is assumed that these cells are the daughters of cells from the fragments which were not active antibody producers at the beginning, but differentiated, during the culture, into cells endowed with two capacities: glass adherence and antibody synthesis. One can further admit that the type of culture employed exerts a selective pressure favoring formation of antibody-producing cells.