Monoclonal antibody mapping of the envelope glycoprotein of the dengue 2 virus, Jamaica

Although dengue (DEN) virus is the etiologic agent of dengue fever, the most prevalent vector-borne viral disease in the world, precise information on the antigenic structure of the dengue virion is limited. We have prepared a set of murine monoclonal antibodies (Mabs) specific for the envelope (E) glycoprotein of DEN 2 virus and used these antibodies in a comprehensive biological and biochemical analysis to identify 16 epitopes. Following domain nomenclature developed for the related flavivirus, tick-bourne encephalitis, three functional domains were identified. Five epitopes associated with domain A were arranged in three spatially independently regions. These A-domain epitopes were destroyed by reduction, and antibodies reactive with these epitopes were able to block virus hemagglutination, neutralize virus infectivity, and block virus haemagglutination, neutralize virus infectivity, and block virus-mediated cell membrane fusion. Domain-A epitopes were present on the full-length E glycoprotein, a 45-kDa tryptic peptide representing its first 400 amino acids (aa) and a 22-kDA tryptic peptide representing at least aa 1-120. Four epitopes mapped into domain B, as determined by their partial resistance to reduction and the localization of these epitopes on a 9-kDa tryptic or chymotryptic peptide fragment (aa 300-400). One domain-B-reactive MAb was also capable of binding to a DEN 2 synthetic peptide corresponding to aa 333-351 of the E glycoprotein, confirming the location of this domain. Domain-B epitopes elicited MAbs that were potent neutralizers of virus infectivity and blocked hemagglutination, but they did not block virus-mediated cell-membrane fusion. Domains A and B were spatially associated. As with tick-bourne encephalitis virus, determination of domain C was more problematic: however, at least four epitopes and biochemical characteristics consistent with C-domain epitopes(AU)

Cell surface phenotype and human T lymphotropic virus type 1 antigen expression in 12 T cell lines derived from peripheral blood and cerebrospinal fluid of West Indian, Guyanese and African patients with tropical spastic paraparesis

Twelve long term cell lines were established from peripheral blood mononuclear cells (PBMC) or cerebrospinal fluid cells of patients with human T lymphotropic virus type I (HTLV-I) seropositive tropical spastic paraparesis (TSP) originating from the French West Indies, French Guyana or the Central African Republic. Most of these long term interlukin-2-dependent cell lines exhibited a pattern characteristic of CD4+ -activated T cells with high expression of CD2, CD3 and CD4 antigens, associated with a strong density of TAC and DR molecules. Nevertheless, in five cases CD8 expression was present at a significant level. HTLV-I antigens were expressed in a few cells after short-term culture and after 4 months the majority of the cells were HTLV-I positive, as demonstrated by indirect immunofluorescence (IF) using polyclonal or monoclonal anti-p19 and anti-p24 antibodies. Low and variable levels of reverse transcriptase activity were detected in supernatant fluids of these cell lines only after 4 months of culture, when at least 50 percent of the cells exhibited HTLV-I antigens by IF. However numerous type C HTLV-I-like viral particles were detected, mostly in the extracellular spaces, with rare budding particles. Similar findings were found in three T cell lines derived from West Indian and African patients with adult T-cell leukaemia/lymphoma (ATLL). Differences in high M-r polypeptides were detected by Western blot in cell lysates when comparing TSP-or ATLL-derived T cell lines. Thus a signal of 62K was easily detectable in all the TSP lines, but not in the ATLL lines. In all cell lines bands corresponding to p53, p24 and p19 viral core polypeptides were present, as was the env gene-coded protein p46. (AU)

Dengue in the Caribbean: virus isolation in a mosquito (Aedes pseudoscutellaris) cell line

During outbreaks of dengue fever in the Caribbean in 1977 and 1978 a continuous cell line derived from Aedes pseudoscutellaris was successfully used for the isolation of dengue virus strains from acute human sera, 238 strains were isolated and culture fluid was successfully used as antigen for the identification of several strains. The isolates all produced a marked syncytial cytopathic effect often visible as early as four days after inoculation. The method was successfully employed in the field where, because of their low optimal incubation temperature, the cells suffered no ill effects under ambient conditions. The isolation method was found to be much more sensitive than conventional mouse inoculation (AU)

Modification of diamine oxidase activity in vitro by metabolites of asparagine and differences in asparagine decarboxylation in normal and virus-transformed baby hamster kidney cells

The oxidation of putrescine in vitro by pig kidney diamine oxidase (EC 1.4.3.6) was increased in the presence of 2-oxosuccinamic acid and malonamic acid. It was inhibited by 3-aminopropionamide, oxaloacetate and pyruvate. 2-Oxosuccinamate was derived from asparagine in virus-transformed baby hamster kidney (BHK) cells growing in tissue culture. Asparagine was decarboxylated more efficiently by transformed than by normal BHK cells. In BHK cells transformed by polyoma virus (Py BHK), 2-oxosuccinamate is the most likely immediate precursor of the 14 CO2 arising from [U-14C] asparagine, and there was some evidence for its formation in an asparagine-dependent clone of BHK cells before and after their transformation by hamster sarcoma virus (respectivey Asn- and HSV Asn-). The relationship between 2-oxosuccinamate and pyruvate and the possible roles of these two substances in controlling cellular diamine oxidase activity are discussed (AU)

The anti-growth properties of extracts from momordica charantia L

Crude and purified extracts from M. charantia plants were tested for their anti-growth properties on a variety of biological materials. These extracts inhibited the germination of maize, cotton and broad bean seeds, as well as the formation of adventitious roots on Bryophyllum leaves. The neutralized acidic fraction also inhibited the division of sea urchin eggs and foetal development in rats, caused a slight increase of the life expectancy of mice bearing tumours of Sarcoma 180, and suppressed the growth of Her2 cells in tissue culture. Oral administration of the crude whole plant extract to a lymphatic leukaemic patient caused a marked increase in the haemoglobin content of teh blood and a noticeable decrease in the white bloob cells. When the crude extract was fractionated on resin columns and then on chromatographic paper, a yellow material was separated and analysed for its elemental constituents. Where tested, it proved to be a more potent growth inhibitor than the whole plant extract or other fractions thereof (AU)

Recovery of dengue-2 and dengue-3 viruses from man in Jamaica

Dengue-like illness has been reported in Jamaica since 1824, although the viruses concerned were never isolated. The emphasis of this work was isolating and typing the etiologic agents involved; 679 cases were reported to the Microbiology Department, University of the West Indies, during 1968 and 1969. Primary serum samples were tested; 112 of 175 indicated recent arbovirus group B infections. Primary infections and reinfections with dengue viruses were indicated by hemagglutination-inhibition and complement-fixation tests. Challenge-virus resistance technique was used to isolate eight agents from human serum. Six of these strains have been typed as dengue-3 and two as dengue-2 viruses.(AU)