[Monoclonal antibodies to dengue virus 4: the spectrum of the reactivity to 4 serotypes of dengue]. / Anticuerpos monoclonales al virus dengue 4: espectro de reactividad a los 4 serotipos del dengue.

These types of monoclonal antibodies 8E8, 3F7 and 1E9 to dengue 4 virus H-241 strain. These monoclonal antibodies show various patterns of reactivity to the four dengue serotypes and different antigen preparations of serotype 4 when they were tested in various serological methods. The monoclonal antibody 8E8 exhibited a specificity of serotype (D-2; by hemagglutination inhibition); subcomplex (D-2 and D-4 by immunofluorescence) and complex (by immunoperoxidase technique). It was able to neutralize by 80% homologous virus and it turned out to be the only reactive monoclonal antibody in the complement fixation test. The monoclonal 3F7 did not react to by hemagglutination inhibition, recognized serotypes D-1, D-2, D-3 and D-4 by immunofluorescence and only serotypes D1 and D4 by immunoperoxidase technique but it was unable to neutralize the homologous virus. The 1E9 antibody was reactive to serotypes D1, D-2, D-3 and D-4 only by hemagglutination inhibition and neutralized serotype D-4. All the monoclonal antibodies were able to react to various dengue antigens through an ELISA of double antibody and showed fluorescent activity against 38th pass in Beagle dog kidney culture; however, they could not react to a D-4 recombinant antigen.

[Dengue virus-specific antigen lymphoproliferation assay with human T cells]. / Ensayo de linfoproliferación antígeno específico al virus dengue con células T humanas.

Papers dealing with the study of the immune response to dengue virus infection and with the role it may play in the pathogenesis of dengue hemorrhaghic fever are increasingly important. The memory human T cell response in individuals with history of dengue infection during the Cuban epidemic was studied in this paper for a further evaluation of the antigenicity of viral proteins. To this end, mononuclear cells of peripheral blood from individuals immune to dengue and from a group of control subjects with viral antigens were incubated. It was obtained a significant proliferative response of lymphocytes from individuals with history of infection against dengue virus type 2 compared with control subjects. It was proved this way the dengue virus-specific memory T CD4+ cell response in the individuals under study.

[Emergence of dengue hemorrhagic fever in the Americas. Reemergence of dengue]. / La emergencia de la fiebre hemorrágica del dengue en las Américas. Reemergencia del dengue.

Dengue is at present the most important human arbovirosis. It is the main cause of hospitalization and death among children from southeast Asia. Two fifth of the world population live in dengue risk areas. In 1997, over 100 countries reported epidemic and more than 50,000,000 cases and 25,000 deaths were estomated. Nowadays, the Americas is passing through the same situation Asia faced years ago. In 1997, 27 countries reported cases of dengue, and in 14 of them cases of dengue hemorrhagic fever were documented. In all, 387,459 cases of classic dengue and 11,645 of dengue hemorrhagic fever were registered. During the last 2 decades dengue has increased significantly in our region with ups and downs in the annual incidence since 1981. It should be remarked that every 3 or 4 years there is a cyclic decrease and a further increase of the incidence, though it trends to rise. As regards dengue hemorrhagic fever, the situation is not more favorable. The Cuban epidemic that appeared in 1981 was completely untimely in the region. In 1989, 8 years later, the second important dengue hemorrhagic fever epidemic emerged in Venezuela, and from that moment on there has been an increasing tendency of this clinical form of the disease. The factors of the emergence and reemergence are present and rise year after year. The neoliberal policies and the consequent privatization of the health services in most of the countries allow us to watch a gloomy future in relation to the development of dengue and its severe form, the dengue hemorrhagic fever/dengue shock syndrome.

[Assessment of the cellular immune response induced in Balb/C mice with dengue virus 2 envelope protein]. / Evaluación de la respuesta inmune celular inducida en ratones Balb/C por la proteína de envoltura del virus dengue 2.

The cellular immune response to dengue type 2 virus envelope protein was studied. To this end, the lympho-proliferative capacity of T-lymphocytes obtained from splenocytes of animals immunized with the protein when they were stimulated by such protein and dengue 2 virus. It was realized that splenocytes proliferated significantly in response to both types of viral antigens and that the values of stimulation indexes were higher in response to the whole virus than to the protein alone. Based on the above-mentioned, it was concludes that purified dengue 2 virus envelope protein was capable of generating specific and memory responses of antigen T-cell to dengue 2 type virus.

[The standardization of the plaque reduction technic for differentiating a dengue infection from a yellow fever infection]. / Normalización de la técnica de reducción de placas para diferenciar una infección por dengue de una infección por fiebre amarilla.

The plaque reduction neutralization assay was standardized to differentiate an infection caused by dengue from another infection produced by yellow fever. Serum samples from Cuban donors were used to this end. Information on previous vaccination against yellow fever was available. Samples from Costa Rican patients with a clinical picture of dengue and with no antecedents of vaccination against yellow fever were also utilized. The optimal plaque staining day was the fifth day and the smallest serum dilution capable of differentiating an infection resulting from dengue from another infection caused by yellow fever was of 1/5. According to the high specificity of the standardized technique, risk factor studies of dengue hemorrhagic fever could be made among individuals vaccinated against yellow fever, which is a present and important topic.

[New evidence of the antigenic relation between the viruses of epidemic neuropathy and the human nervous system. A study of the immune cellular response in patients with epidemic neuropathy and controls. A review of the topic]. / Nuevas evidencias de la relación antigénica entre los virus de la neuropatía epidémica y el sistema nervioso humano. Estudio de la respuesta inmune celular en pacientes con neuropatía epidémica y controles. Revisión del tema.

A series of experiments was made at the Virology Department of the "Pedro Kourí" Institute of Tropical Medicine aimed at obtaining new evidences on the possible antigenic relations existing between the viruses isolated from patients with epidemic neuropathy and the structures of the human nervous system. According to the results it may be finally inferred that the persistence and/or autoimmunity may be considered as mechanisms through which the studied viruses participate in the etiopathogenesis of the epidemic neuropathy in Cuba. For future experiments it is very important to identify the possible viral epitopes involved in the molecular mimicry that are responsible for the probable autoimmune mechanisms or for the viral persistence.

[The genomic characterization of the Cuban strain with a light cytopathic effect]. / Caracterización genómica de la cepa cubana de efecto citopático ligero.

The genomic characterization of the strain of light cytopathic effect by nucleotide sequence is presented. It was possible to sequence 90% of the strain of light cytopathic effect. A close relationship with Coxsackie A9 was observed. The greatest mutations occurred in the region of the genome that codifies for the structural proteins. Therefore, it may be considered as a variant of Coxsackie A9 never reported before.

[The rapid identification of dengue virus serotypes by the polymerase chain reaction]. / Identificación rápida de los serotipos del virus del dengue mediante la reacción en cadena de la polimerasa.

4 primer sets, were used to allow the amplification of a nucleotide sequence with unique size for each of the dengue virus serotypes by polymerase chain reaction (PRC). The method consisted in the extraction of ribonucleic acid from supernatant of infected cell cultures, reverse transcription-polymerase chain reaction (RT-PCR). This was completed in approximately 7 hours in a simple tube. The size of the amplified sequence was evidenced by electrophoresis in Agarose gel stained with ethidium. The method showed a sensitivity of at least 2.5 plate forming units (pfu) per tube of reaction. It es useful for the detection and simultaneous identification of the 4 serotypes, starting from supernatants of infected strains cultures from different countries of the Caribbean, Central America, and South America.

[Inhibition of the multiplication of a Coxsackie A9 strain isolated from a patient with epidemic neuropathy by the interferons alfa and gamma]. / Inhibición de la multiplicación de la cepa de Coxsackie A9 aislada de un paciente con neuropatía epidémica frente a los interferones alfa y gamma.

We present the results of the in vitro action of alpha and gamma interferons and of Intacglobin and Igegam against the 47/93/IPK (Coxsackie A9) strain isolated from the cerebrospinal fluid of a patient with epidemic neuropathy. The in vitro studies showed that the two interferons inhibited the replication of this agent; they also showed the presence of antibodies to it in the Intacglobin and Igegam. The results attained demonstrated that the use of these compounds could be effective for the treatment of this entity.

[Use of a dengue anti-complex monoclonal antibody in viral purification]. / Empleo de un anticuerpo monoclonal anticomplejo dengue en la purificación viral.

The purification of different serotypes of dengue virus from a monoclonal antibody which recognizes an epitope present in the four serotypes bond to a Sepharose 4B matrix activated with cyanogen bromide, is reported. Results evidence that the method employed makes quicker the process of purification with a high degree of purity.

[Standardization of an indirect ultramicro ELISA for the determination of total antibodies against the measles virus]. / Estandarización de un sistema ultramicroELISA indirecto para la determinación de anticuerpos totales al virus del sarampión.

An indirect ultramicro ELISA system (UME) for the determination of antibodies to measles virus by the cuban technology of Ultramicro Analytical Systems (SUMA) was developed. A number of 448 serum samples from the National System of Seroepidemiological Surveillance of Measles were simultaneously processed by the Ultramicro ELISA system and by the haemagglutination inhibition technique. Results were compared in both assays. Afterwards; 120 serum pairs obtained from the same source were studies and processed in a similar way. Results evidenced the usefulness of such immunoenzymatic system for the serological diagnosis and the positive validation of replacing conventional techniques by this novel technology.

[Evaluation of an ultramicroELISA system for the diagnosis of rubella]. / Evaluación de un sistema ultramicroELISA para el diagnóstico de la rubéola.

An indirect Ultramicro ELISA assay, previously standardized in our laboratory, for detecting antibodies IgG to the rubella virus was assessed in comparison to the hemagglutination inhibition technique. This assessment allowed to determine its efficacy in the National System for Epidemiological Surveillance of this entity. One hundred and ninety serum pairs of clinically suspected cases of rubella were studied and a high percent of coincidence (99.4%), specificity (99.4%), and sensitivity (100%) was found between both techniques. In addition, 73 serum samples of blood donors were processed using an indirect microELISA system (Berhing) which was compared to the Ultramicro ELISA technique for rubella and it showed a 100% of sensitivity, specificity, and coincidence.

[Comparison of latex agglutination technics and polyacrylamide gel electrophoresis for the rotavirus diagnosis. Habana City, 1986]. / Comparación de las técnicas de aglutinación por latex y la electroforesis en gel de poliacrilamida para el diagnóstico de rotavirus. Ciudad de la Habana, 1986.

Two methods for the diagnosis of rotavirus are compared with 120 stool samples from children under two years of age who had been hospitalized in Centro Habana Children's Hospital with a clinical diagnosis of acute diarrheal disease and 30 samples of healthy children of the same age group who served as controls. The methods used were latex agglutination (Rotalex, commercially-available kit from ORION DIAGNOSTIC ESPOO, Finland) and polyacrylamide gel electrophoresis. Electronic microscopy was used to define those cases whose results did not coincide with the previous techniques. Comparison was made based on the sensitivity and specificity, cost and easiness of performance. Rotalex was less specific but more sensitive than electrophoresis in polyacrylamide gel. The latter is less expensive, since reactants are available at a lower price in dollars and have no expiration date, is very useful in epidemiologic and outbreak studies, since it detects subgroups of circulating rotavirus and it is a painstaking technique (1-20 samples in 10 hours). Rotalex is simple, rapid (1-20 samples in 30 minutes) and allows individual determinations; therefore, we consider its application in hospitals is feasible.

[Rotavirus infection in children with acute diarrhea in Habana City]. / Infección por rotavirus en niños con diarrea aguda en ciudad de la Habana.

This paper shows the incidence of rotavirus and other pathogenic agents in 256 children under three years of age with a diagnosis of acute diarrhea. This study included the months of December 1983 through May 1984. Rotavirus was found in 27.7% of patients, followed by enteropathogenic E. coli (17%). No positive cases were found in the control group. The highest incidence of rotavirus infection coincided with the coldest months where the lowest volumes of rains were reported.

[Serologic study of arbovirus in 2 localities of the Juventud island]. / Estudio serológico de arbovirus en 2 localidades de la Isla de la Juventud.

A serologic study is made in two population groups in the Isle of Youth. A total 268 blood samples in blotting paper are subjected to the hemagglutination inhibition technique, using the Eastern equine encephalomyelitis, Western equine encephalomyelitis, Saint Louis encephalitis, and dengue 2 viruses; 16% positivity to flavivirus was found. A second serum sample was taken in people positive by the hemagglutination inhibition technique in order to carry out the techniques of complement fixation and plate reduction neutralization. Nine cases showed complement-fixating antibodies, which is indicative of recent infection and in 29 cases neutralizing antibodies to SLE virus were found.

[Retrospective sero-epidemiologic survey on dengue virus in the municipalities of Cienfuegos and Palmira]. / Encuesta seroepidemiológica retrospectiva a virus dengue en los municipios Cienfuegos y Palmira.

A retrospective seroepidemiologic survey is made in the municipalities of Cienfuegos and Palmira to determine the presence of neutralizing antibodies to Den-1 and -2 virus in the population. It was found that 21.4% of the population studied had antibodies to Den-1, 12.3% to Den-2, and that 5.5% had been infected by the two serotypes (secondary infection). It became apparent that in the Palmira municipality the percentage of infection due to Den-1 was higher and it was found that in 1980-1981 there was a late dengue (Den-1) outbreak. Therefore, this municipality was probably the only in the country with 2 epidemic outbreaks due to two dengue serotypes (1 and 2) in a 6 month interval. The potential relationship between this fact and the high lethality of hemorrhagic dengue fever in this municipality is established. The influence of environmental, social, and sanitary factors on the risk of infection is suggested. It was found that Whites and Blacks are equally infected and that infection is not a random phenomenon, instead it is favored by the presence of vectors in and around the housing.