A radioimmunoprecipitation method in the serodiagnosis of HIV infection: the development of the optimal conditions for its performance and the evaluation of the possibilities for its use

The optimum conditions for using the method of radioimmunoprecipitation (RIP) for the detection of human immunodeficiency virus (HIV) in serum samples have been established. Out of several available cell lines persistently infected with HIV, specially selected line 17 has been chosen. The characteristic feature of this is the high and stable (under the conditions of prolonged cultivation) accumulation of virus-specific proteins in infected cells. The optimum conditions for making the test and its evaluation have also been established. The data of literature on the advantages of the method of RIP over such traditional methods as the enzyme immunoassay and immunoblotting have been confirmed. Thus, the presence of specific antibodies in several serum samples registered as false negative has been established. The intertypical reactivity of two serotypes of the virus, HIV-1 and HIV-2, has been studied. Cross reactivity of antibodies with respect to the HIV gene gag, but not with respect to viral glycoproteids, has been established. Ideas on the expediency and prospects of using RIP for the serological control of HIV infection are presented.     

H-2-linked genetic control of the plaque-forming cell response to sheep red blood cells

The role of genes linked to the H-2 locus in effecting an immune response to SRBC was examined using strains of mice which differ in the classes of antibodies produced following multiple injections with SRBC. While H-2-linked gene action appeared to be at the level of regulating the number of plaque-forming cells (PFC) present in the spleens of different strains following two injections with SRBC, non-H-2-linked immune response genes seemed to determine whether an IgM-IgG switch occurred as well as how much of each antibody class was produced by the number of PFC available as a result of H-2-linked gene intervention. Mapping studies showed that the H-2-linked genetic effects were due to either the requirement for two genes or the presence of genes located between I-B and H-2D.     

Evolution of asymbiotic nitrogen fixation

Recent observations on the nature of the enzyme complex, nitrogenase, prepared from a variety of nitrogen-fixing micro-organisms, on its substrate specificity, energy requirements, source of reducing power and sensitivity to O₂ now permit speculation on the evolution of biological nitrogen fixation in asymbiotic micro-organisms.Ability to fix N₂ is restricted to procaryotic organisms and is particularly widespread among those having characteristics (e.g. hydrogenase, ferredoxin) regarded as primitive. If the primitive environment was devoid of O₂, the earliest N₂-fixing prokaryote would have been a strict anaerobe, not unlike Clostridium pasteurianum. Yet N₂-fixation seems unnecessary in a primitive ammonia-containing environment, and ammonia represses this function in contemporary species. This apparent paradox, the development of the ability to fix N₂ in circumstances in which it was apparently unnecessary suggests that a substance other than N₂ might have been primary substrate of the primeval enzyme.Substances such as acetylene, cyanide, cyanogen, nitriles or isonitriles are all substrates for nitrogenase and are all probable components of the primitive terrestrial environment. Biologically useful functions which a nitrogenase-like reductase system might have served involving substrates other than N₂ include: (a) a detoxification reaction to nullify the effects of cyanide or cyanogen; (b) a means of generating ATP anaerobically; (c) a hydrogen “escape valve”.Functions (b) and (c) are improbable because they would be physiologically uneconomic; function (a) is plausible.With the emergence of an oxidizing atmosphere, facultative and aerobic N₂-fixing micro-organisms could only retain the nitrogenase system if the O₂-sensitive component was protected from inactivation. In the Azotobacteraceae this is achieved by “conformational protection” together with a high respiration rate; in blue-green algae, a structural compartmentation occurs in the more highly evolved species.