The 9,213-nucleotide structure of the AIDS/lymphadenopathy virus has been determined from molecular clones representing the integrated provirus and viral RNA. The sequence reveals that the virus is highly polymorphic and lacks significant nucleotide homology with type C retroviruses characterized previously. Together with an analysis of the two major viral subgenomic RNAs, these studies establish the coding frames for the gag, pol and env genes and predict the expression of a novel gene at the 3' end of the genome unrelated to the X genes of HTLV-1 and -II.
A chemically-synthesized gene and natural complementary DNA coding for human lymphotoxin were isolated and engineered for expression in Escherichia coli. Purified recombinant lymphotoxin shows cytotoxic activity on murine and human tumour cell lines in vitro and causes necrosis of certain murine sarcomas in vivo.
An outbreak of waterborne cryptosporidiosis affecting 27 persons, diagnosed stool positive, occurred in Ayrshire in April 1988. Twenty-one in 27 confirmed cases required some form of fluid replacement therapy. Local general practitioners indicated a two- to fivefold increase in diarrhoeal disease during the outbreak, and following enquiries made by Environmental Health Officers it became apparent that many hundreds of people had suffered a diarrhoeal illness at that time. Cryptosporidium spp. oocysts were detected in the treated chlorinated water supply system, in the absence of faecal bacterial indicators. Oocyst contamination of a break-pressure tank containing final water for distribution was the cause of this waterborne outbreak. An irregular seepage of oocyst-containing water, which increased during heavy rains, was the cause of the break-pressure tank contamination, rather than a failure of the water-treatment processes. The waterborne route should be considered when clusters of cryptosporidiosis-associated with potable water occur. Waterborne cryptosporidiosis can occur in the absence of other faecal indicators of contamination.
The multiple biological activities present in semipurified lymphokine preparations have made it difficult to assign discrete biological functions to each lymphokine. As a result, the large number of identified lymphokine activities may actually reflect the manifestations of a few factors. While this research has also been hampered by the limited quantities of lymphokines available, hybridoma and recombinant DNA technologies have begun to help overcome these limitations.Macrophage activation has been intensively investigated because it is generally agreed that activated macrophages play an essential role in the defense against microorganisms and in the immune response against neoplasia (1). Macrophage activation mediated by macrophage activation factor (MAF) 1 and gamma interferon (IFN-'y) has been characterized by similar morphologic, metabolic, and functional changes (2-6) including stimulation of nonspecific tumoricidal activities (5), induction of Ia antigen expression (7, 8), increased Fc receptor expression (0, 10), production of plasminogen activator (I 1), and production of hydrogen peroxide (12). Several investigators (5,8,12,13) have postulated therefore that IFN-q~ and MAF may be identical. In support, Schreiber et al. (14) have recently demonstrated biosynthetic and biochemical similarities of IFN-'y and MAF produced by a murine T cell hybridoma (24/G1). Both the antiviral and MAF activities of 24/G1 cultured supernatants were neutralized by anti-IFN-% but not anti- . have demonstrated neutralization of MAF activity with polyclonal antMFN-7, definitive results could not be ascertained since these antisera were prepared from partially purified preparations and could contain antibodies that neutralize other lymphokine activities.In the present report, murine IFN-~ produced by recombinant DNA techniques (18) (>00% pure) was tested for MAF activity; special attention was given
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