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Saint Louis encephalitis virus belongs to Flavivirus genus; Flaviviridae family jointly with other medically important flaviviruses including dengue virus and West Nile virus. The biological properties and functions of prM flavivirus protein are under investigation due to its importance in the generation of infectious virion and host interactions. Monoclonal antibodies have become powerful tools in this approach. Also the use of monoclonal antibodies has been successfully applied for antigenic analysis, clinical diagnosis and treatments. Here, using an immunofluorescence assay we describe a monoclonal antibody (mAb 3D2) that uniquely recognizes native prM Saint Louis encephalitis virus protein expressed in either C6/36-HT or Vero cells. In conclusion, mAb3D2 has significant potential for use in (a) the diagnosis of infections caused by this virus and (b) therapeutic use to treat patients infected by this virus and fundamental research to understand the role of the prM in the Saint Louis encephalitis virus infectious process.

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Dengue virus is the most significant virus transmitted by arthropods worldwide and may cause a potentially fatal systemic disease named dengue hemorrhagic fever. In this work, dengue virus serotype 4 was detected in the tissues of one fatal dengue hemorrhagic fever case using electron immunomicroscopy and molecular methods. This is the first report of dengue virus polypeptides findings by electron immunomicroscopy in human samples. In addition, not-previously-documented virus-like particles visualized in spleen, hepatic, brain, and pulmonary tissues from a dengue case are discussed.

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Dengue fever (DF) and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) are considered the most important arthropod-borne viral diseases in terms of morbidity and mortality. The emergency and severity of dengue (Den) infections increase the necessity of an early, quick and effective dengue laboratory diagnostic. Viral isolation is considered a gold standard for diagnosis of dengue infection using monoclonal antibodies (mAbs) as a tool for determining serotype specificity. Alternatives have been used to improve sensitivity and time to dengue diagnosis. Based on the early expression of dengue C protein in the life cycle, we focused our study on the application of an anti-dengue 2 virus capsid protein mAb in dengue diagnosis. The kinetic expression of dengue-2 capsid in mosquito cells and its immuno-localization in experimentally infected suckling albin Swiss (OF-1) mice brain tissues was established. The results demonstrate the possible utility of this mAb in early dengue diagnosis versus traditional isolation. In addition, a preliminary study of an enzyme immunoassay method using 8H8 mAb for specific detection of dengue C protein antigen was performed, making possible recombinant C protein quantification. The results suggest that detection of dengue capsid protein could be useful in the diagnosis of early dengue infection.

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The objective of this study is to identify the attitude toward the homosexuals and lesbians among graduate students of General Public Health and Health Education Program at School of Public Health, Medical Sciences Campus of the University of Puerto Rico. A descriptive-92 graduate students of the correlational design was used to carry out the study participated in the study General Public Health and Health Education programs. The data collection was collected through a self-administered questionnaire. Descriptive and inferential statistics (Chi-square and t-test student) were used to data analysis. The 82.6% of the participants had a prejudiced attitude toward the homosexuals and the lesbians. The 79.3% presented a low distance level. There is a significant association among the social distance, homosexual and lesbian educational exposure and the years of studies. To develop appropriate strategies to foment the acceptance and eliminate the prejudice toward the homosexuals and lesbians in the participants, what will impact in a better way of providing quality health services.

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OBJECTIVES: The kinetics of three serological markers (IgM, IgA, and IgG) in serum, saliva, and urine samples from adult patients with primary or secondary dengue infection were studied. DESIGN: Serum, saliva, and urine samples were collected from 22 patients with clinical and confirmed dengue 3 virus infection during the outbreak in Havana City in 2001. They were tested by capture IgM (MAC-ELISA), IgA (AAC-ELISA), and IgE (EAC-ELISA) and IgG ELISA inhibition method (EIM) to detect specific dengue antibodies. RESULTS: Similar kinetics were observed in IgM, IgA, and IgG antibodies in saliva and IgA and IgG in urine samples from secondary cases compared with kinetics in serum samples, although the values were lower. No IgG antibody was detected in saliva and urine samples in primary cases and IgM antibody was not detected in urine samples from either primary or secondary infection. All secondary cases were positive for IgG in saliva and urine samples at day 7. The kinetics of specific IgE antibodies in primary and secondary cases were different. CONCLUSIONS: The kinetics of three serological markers (IgM, IgA, and IgG) in serum, saliva, and urine samples from adult patients with primary or secondary dengue 3 virus infection were studied for the first time, showing its behavior and usefulness in dengue virus diagnosis. The specific IgE could play a role as a serological marker in secondary infections.

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Cuban DHF/DSS outbreaks have provided evidence of a reduced risk of people of Negroid race for DHF/DSS compared to those of Caucasoid race. These observations from Cuban dengue outbreaks have significant epidemiological interest, as the differences in susceptibility to DHF/DSS among racial groups in Cuba coincide with that reported in African and Black Caribbean populations. In this article, we review the literature on race as a risk factor for DHF/DSS and discuss recent results from ongoing studies. Taking into consideration the origins of contemporary Cuban inhabitants, we propose that the Cuban, Caribbean Black and African populations share a common gene pool that could explain, at least partially, the low incidence of dengue hemorrhagic fever in Cuba and Caribbean and African countries. The central role played by immunological mechanisms in the pathogenesis of DHF/DSS has led us to consider that the polymorphic genes associated with the immune response must be carefully considered among those human genes regulating dengue disease severity that might be distributed unequally in Blacks and Whites.

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OBJECTIVE: Differential diagnosis of infections that cause similar diseases and may be active simultaneously in the same geographical areas is greatly needed. Dengue and yellow fever viruses (DENV and YFV) are transmitted by the same species of mosquito and both can cause haemorrhagic fever symptoms. These viruses are active mainly in regions where expensive and sophisticated technologies are not available. Our objective was to develop a simple, reliable and easy-to-perform method to detect and identify these viruses. METHODS: We slightly modified a generic RT-PCR able to detect the mentioned viruses and other members of this genus: specific primers for each one of these viruses were designed and included in the nested reaction instead of one of the generic ones. The reaction was optimized and viruses are amplified giving rise to bands of different sizes distinguishable in agarose gels. RESULTS: This test is able to detect and identify the four DENVs and YFV to a high level of sensitivity and specificity and can be used with clinical samples. This simple, reliable and easy-to-perform method able to detect and identify dengue 1-4 and YFV can be used in poor endemic countries.

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Acute and late convalescent sera (collected at day 5 of disease onset and 1 year later) from dengue fever (DF) and dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) laboratory confirmed cases, were tested for antibody-dependent cell-mediated cytotoxicity (ADCC) activity using dengue 1 (DENV-1) or dengue 2 (DENV-2) infected cells as target. All patients experienced their first dengue virus (DENV) infection 20 years before. ADCC activity was detected in acute sera from DHF/DSS but not in sera from DF patients. However, 1 year after illness, ADCC activity was observed in all cases. This preliminary report represents one of the few studies of ADCC in dengue patients and suggests that ADCC could be implicated in dengue pathogenesis.

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BACKGROUND: The detection of the IgM antibody for the dengue virus in serum by ELISA has become one of the most important and useful methods for diagnosis of dengue using a single acute-phase serum sample. Currently, this system is an invaluable tool for the surveillance of dengue fever (DF) and dengue hemorrhagic fever (DHF). The usefulness of other serological markers such as IgA and IgE have been less studied. OBJECTIVE: To study the IgM, IgA and IgE specific antibody response in dengue 3 infected patients with different clinical picture and type of infection. STUDY DESIGN: One hundred and twenty-seven serum samples collected on days 5-7 at the onset of fever from clinically and serologically confirmed dengue cases were studied. Forty-two were classified as primary dengue fever cases, 48 as secondary dengue fever cases and 37 as secondary dengue hemorrhagic fever cases. All samples were tested by capture ELISA in order to detect dengue IgM, IgA and IgE antibodies. RESULTS AND CONCLUSIONS: In this study, significant differences were observed in the IgM, IgA and IgE response between the study groups. High IgA and IgE OD ratios in secondary dengue cases were found. The usefulness of serotype specific IgM antibody detection is also analyzed and discussed. A priority for future dengue research in terms of protection, recovery of infection and immunopathogenesis is to elucidate the role of these immunoglobulins. The cross reactivity response to IgM between dengue virus serotypes in primary and secondary cases should also be more studied.

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Flaviviruses are a widespread and numerous group of arboviruses that can cause serious illness in humans. The continuous and slow spread of certain flaviviruses, such as Dengue viruses, and the recent entry and spread of West Nile virus to the American continent, point to the need to control these infections. This control requires the use of suitable techniques for diagnostic and surveillance programmes. A generic RT-nested-PCR that is, theoretically, able to detect each member of the group has been designed. The identification of the detected virus is carried out by sequencing. The introduction of an internal control would reduce the number of false negative results and could be used to quantify the viral load in clinical samples where the method works well.

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It was recently reported that disease severity increased during the 1997 Cuban dengue 2 virus epidemic and it was suggested that this might be explained by the appearance of neutralization resistant escape mutants. We investigated these observations and ideas by sequencing 20 dengue 2 virus isolates obtained during the early (low case fatality rate) and the late (high case fatality rate) phases of the outbreak. Our results showed total conservation of the E gene sequence for these isolates suggesting that the selection of envelope gene escape mutants was not the determinant of increased disease severity. Alignment of these sequences with those available in GenBank, followed by Maximum likelihood phylogenetic analysis generated a tree, which indicated that our isolates are closely related to the virus that circulated in Venezuela in 1997/98 and subsequently in Martinique in 1998. This "American/Asian" genotype has therefore gradually dispersed across the Caribbean region during the past 5 years.

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We have expressed a recombinant Dengue 4 virus envelope glycoprotein (E4rec), truncated at its C-terminus by 53 amino acids, in Pichia pastoris. The presence of E4rec was confirmed by Western-blot using anti-DEN 4 hyper immune mouse ascitic fluid. E4rec migrated during SDS-PAGE as a 64 kDa protein. Treatment with endoglycosidases showed that the E protein was modified by the addition of short mannose chains and the absence of hyperglycosylation. When administered to BALB-C mice, E4rec elicited a DEN 4 neutralizing antibody response haemagglutination inhibition antibodies and specific memory T cell response. Mice immunized were also significantly protected against lethal DEN 4 virus challenge (86.6%, p < 0.001).

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Different combinations of pHs (2 to 12) and temperatures (25, 30 and 35 degrees C) were tested to obtain a protein isolate from ebony (Pithecellobium flexicaule, Benth) seeds. Seed proteins contained 54.6 per cent albumins, 32 per cent globulins, 5.7 per cent glutelins and 1.3 per cent prolamins. The isoelectric points for albumins, globulins and glutelins were in the pH range of 2.3-2.7. The average molecular weight of albumins ranged from 92 to 100 kDa and for the four globulin subunits in the range of 28.4 to 57.3 kDa. For isolate production, proteins were sequentially extracted with distilled water and a 5 per cent NaCl solution. The resulting supernatants were mixed. The best extraction was achieved at pH 11 and 25 degrees C. 45.6 per cent of the total seed protein was precipitated at pH 2.6 yielding an isolate with 90 per cent protein (N x 6.25). The isolate contained high quantities of lysine, leucine, threonine and phenylalanine but were low in sulfur containing amino acids methionine and cysteine. The extraction process reduced tannins, phytates and trypsin inhibitor in 53, 70 and 70 per cent, respectively. In vivo protein digestibility of the protein isolate was 85.4 per cent and the corrected digestibility essential amino acid score was of 44 per cent due to the lack of sulfur containing amino acids. In order to upgrade the protein quality of ebony isolate it is recommend to supplement with methionine or sulfur containing rich foods.

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During the epidemic of optic and peripheral neuropathy which occurred in Cuba in 1992-1993, viruses antigenically related to the Coxsackie viruses were isolated from cerebrospinal fluid of patients. Concurrently with the virologic studies, epidemiologic, toxicologic, nutritional, immunologic, and histopathologic investigations were also carried out. Although it was demonstrated that the illness was associated with toxic and nutritional risk factors, it has not been possible to identify a specific etiology for the symptoms observed. Taking into consideration the results obtained in all of the various investigations, we have formulated an integral, multifactorial hypothesis which attempts to explain a pathophysiologic mechanism by which the viruses isolated could participate in the pathogenesis of the illness. We propose that the viral agents produce a persistent infection, and the possibility that they may act as mediator of an autoimmune pathogenic process.

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OBJECTIVE: The serial passage of dengue viruses in primary dog kidney (PDK) cells has resulted in selection of attenuated viruses. However, the molecular changes responsible for loss of virulence are not well characterized. This article describes the isolation and biologic attributes of one dengue 2 virulent strain as a first step to allow the study of determinants of virulence at the molecular level. METHODS: A15 dengue 2 Cuban strain was isolated from the viremic plasma of a patient with uncomplicated dengue fever during the 1981 epidemic. This was then subjected to serial passage in PDK cells. Viruses resulting from several PDK passages were compared to the parent strain for plaque size and temperature sensitivity, neurovirulence in newborn mice, and cytopathogenic effects on LLC-MK(2) and C6/36-HT cell lines. RESULTS: A15 dengue 2 Cuban strain was successfully propagated in PDK cells. Primary dog kidney 52 to 53 viruses exhibited several biologic attributes, such as small plaques, temperature sensitivity, reduced mouse neurovirulence, and cytopathic effect in permissive cell lines. CONCLUSIONS: These results represent the first step to allow attenuation of this strain of dengue 2 virus.

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In the last few years an increasing rise of new infectious diseases or of other diseases considered to be under control has been observed. The so called emerging and reemerging diseases are those new infections that have come up in a population or those existing diseases which incidence and geographic extension are on a rapid increase. Factors such as social and economic situations, medical assistance, food production, changes in human behaviours, environmental changes, health systems deterioration, and adaptation and changes of microorganisms are related with the emergence or reemergence of a number of entities. This paper sets forth an analysis of the emergence and reemergence of viral diseases and of those factors that have had an impact on this situation.

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