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)

Detection of early human T-cell lymphotropic virus type I antibody patterns during seroconversion among transfusion recipients

From a cohort of human T-cell lymphotropic virus type I (HTLV-I) exposed transfusion recipients (N=71) enrolled in the Jamaican Transfusion Study, 11 were selected for detailed laboratory evaluation. All recipients were followed at monthly intervals for 6 months and then bimonthly up to 1 year for evidence of HTLV-I seroconversion. Without regard to results on screening assays, pretransfusion and posttransfusion samples were tested with two licensed HTLV-I whole-virus screening enzyme immunoassays (EIAs), recombinant EIAs for antibody against tax (p40x) and p21e envelope, standard whole virus Western blot (WB), WB enhanced with recombinant p21e, and radioimmunoprecipitation assay (RIPA). In the early period post transfusion, antibody to gag core protein was predominant with anti-p24 generally appearing before anti-p19. Recombinant anti-p21e envelope protein, in EIA and WB format, was frequently the earliest envelope reactively detected, while anti-gp46 in WB and anti-gp61/68 in RIPA system appeared later. Anti-tax antibodies appeared later in the time course of seroconersion. The whole-virus EIAs were less sensitive than the confirmatory assays. The combination of WB and RIPA or WB enhanced with recombinant p21e appeared equally effective in confirming samples as positive by the Public Health Service two gene group confirmatory algorithm. However specificity of this assay approach could not be addressed in this study.(AU)

Acute respiratory infections in ambulatory malnourished children: a serological study

We studied the aetiological agents of acute respiratory infections occuring in an ambulatory population of 83 malnourished Jamaican-born children aged 6 to 32 months using serological methods for diagnosis. In 60 percent (38/63) of symptomatic children and in 25 percent (5/20) those without reported disease the following microorganisms were observed: parainfluenza viruses in 15 children, influenza viruses in 12, adenovirus in 10, respiratory syncitial virus in 7 and Mycoplasma pneumoniae in 7 children. The prevalence of the viral infections apparently increased with the severity of malnutrition. (AU)

Retroviruses in the Caribbean

Transmission of HIV in many Caribbean countries has followed the pattern of initial predominance among homosexual and bisexual male, with the infection subsequently spreading into the heterosexual community. However, on Saint Lucia the epidemic began among heterosexual contacts of Saint Lucia labourers from Florida; in Bermuda 58 percent of AIDS cases have been in interavenous drug abusers; and in the infected via the perinanatal route. Seroprevalence of the human T-lymphotropic virus, type 1 (HTLV-), whose modes of transmission resemble those of HIV, has been found to range from 2.3 percent in Trinidad and Tobago to 5.4 percent in Jamaica. In a study of HIV and HTLV-1 infection patterns in homosexuals males in Trinidad and Tobago, the cohort was too small for confirmation that coinfection with these two viruses hastended progression to AIDS, but further investigation is warranted. (AU)

Gastroenteritis outbreaks on two Caribbean cruise ships

Outbreaks of gastrointestinal illness on cruise vessels have been caused in the past by contaminated water and by food consumed on the ships or on shore visits. Person-to person transmission has also been strongly suspected on some occasions-in one case, in the setting of repeated outbreaks on consecutive cruises. Laboratory findings implicated Norwalk virus as the pathogenic agent on the first of the Holiday outbreaks. However, all three outbreaks had epidemiologic features characteristic of epidemics of Norwalk virus gastroenteritis. These include: (1) a high attack rate in adults; (2) a high frequency of vomiting; (3) short duration of illness; and (4) absence of identified bacterial pathogens. It is not yet clear whether food or water were vehicles of infection in these outbreaks or whether sanitary deficiencies contributed to the risk of outbreaks of viral enteric disease on these cruise ships. (AU)

Identification of an antigenic and genetic variant of dengue-4 virus from the Caribbean

Twenty-one dengue (DEN) viruses isolated from the Caribbean (Dominica and Jamaica) during the 1981-1982 epidemic year were distinct serological and genetic variants of DEN-4 virus. These isolates were clearly identified as DEN-4 viruses using type-specific monoclonal antibodies in indirect immunofluorescence assays. However, they either were not neutralized, or were neutralized poorly using hyperimmune mouse ascitic fluids (HMAF) or rhesus monkey serum directed against the H-241 prototype strain of DEN-4 virus isolated in the Philippines in 1956. HMAF prepared against a representative Caribbean isolate, however, neutralized with similar effectiveness the homologoous virus, the H-241 prototype strain, and virus strains isolated from the Pacific and Southeast Asian areas from 1973 to 1984. The Caribbean isolate exhibited no more than 30 percent and 16 percent oligonucleotide spot homology with the H-241 and Bankok viruses, respectively, by RNA fingerprint analysis, while demonstrating 82 percent and 89 percent homology with the Gilbert and Niue Island isolates, respectively. The isolation of dengue viruses which are serologically and genetically distinct from the prototype virus emphasizes the need for continued dengue virus surveillance. The recognition of unique dengue isolates should allow the selection of reference strains and vaccine candidate strains which will induce antibodies that are equally effective in neutralizing virus from all geographic areas. (AU)

The human type-C retrovirus, in Blacks from the Caribbean region, and relationship to adult T-cell leukemia/lymphoma

Type-C RNA tumour viruses have been implicated in the etiology of naturally occurring leukemias and lymphomas of animals. Human T-cell leukimia/lymphoma virus (HTLV) is the first human virus of this class consistently identified in association with a specific type of human leukemia/lymphoma. The isolation of HTLV was made possible by the ability to grow mature T-cell in tissue culture usually with T-cell growth factor (TCGF). We now report a cluster usually with T-cell leukemia/lymphoma among Blacks from the Caribbean in which all eight cases are positive for HLV virus and/or antibody. These patients have diseases that appears indistinguisable from Japanese adult T-cell leukemia/lymphoma which, as we have also reported, is associated with HTLV in over 90 percent of cases. The finding of HTLV antibodies in some of the normal population in the Caribbean and Japan, and the clustering of a specific form of T-cell leukemia/lyphoma in these virus-endemic areas, suggest that HTLV infection may be associated with the occurrence of a distinctive clinico-pathologic entity (Summary)

Search for subtype I strains of Venezuelan encephalitis virus among isolates from Trinidad, W.I., during 1960-1972

Twenty-one strains of Venezuelan encephalitis (VE) virus isolated from three habitats in Trinidad, W. I. during 1960 to 1972, were subtype III (Mucambo) VE cirus by plaque-reduction neutralization tests. Like prototype Mucambo virus, each strain killed 8- to 15-week-old mice inoculated intraperitoneally. If the subtype I strain of VE virus that caused a major outbreak in Trinidad during 1943 to 1944 persisted on the island into the 1960s and early 1970s, it did not become the dominant VE virus in these three enzootic foci (AU)

First isolation of Catu virus from a human in Trinidad

The first isolation of Catu virus from a human in Trinidad is reported. It is also the first human isolate outside of Brazil. A convalescent serum neutralized 5.0 logs of the homologous virus.(AU)