[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.

[The characterization of influenza viruses by the immunoperoxidase method using monoclonal antibodies. Its setup and validation]. / Caracterización de los virus de influenza por el método de la inmunoperoxidasa utilizando anticuerpos monoclonales. Montaje y validación.

The immunoperoxidase method for the rapid classification of influenza viruses in type and subtype was applied and validated for the first time in Cuba. The method is based on a rapid culture in MDCK-L cells and on the use of monoclonal antibodies for the classification in type and subtype. A pool of antibodies against influenza A and another against influenza B and HA1-71 and HA2-76 monoclonal antibodies are used for the subtyping in H1 and H3. The validation was carried out by applying this method to 21 international reference strains and to 23 human influenza virus strains that were isolated and previously classified by hemagglutination inhibition. All the strains reacted to the monoclonal antibodies according to their hemagglutinin type and subtype. 6 reference strains and 9 isolations were characterized within the H1N1 subtype: 9 reference strains and 10 isolations in the H3N2 subtype; and 6 reference strains and 4 isolations in type B. There were neither unspecific nor crossed reactions among the controls established. There was 100% of sensitivity, specificity and coincidence. The technique used proved to be fast and convenient for the characterization in type and subtype of the isolated influenza virus strains. It may substitute the classic hemagglutination inhibition method when it is required the rapid characterization of outbreaks or epidemics of acute respiratory infections, which is very important due to the high morbidity they cause mainly in risk groups and to their economic repercussion.

[Standardization of an inhibition ELISA technique for the serologic diagnosis of coxsackie virus group B infections]. / Normalización de un ELISA de inhibición para el diagnóstico serológico de las infecciones por virus coxsackie del grupo B.

An inhibition ELISA technic to detect antibodies aimed at Coxsackie B viruses was standardized. The method was type-specific since it could detect antibodies to 4 Coxsackie B serotypes (it wasn't tried on serotypes B2 and B4 because the strains were not available). The comparison with the neutralization technic showed 85% coincidence, 91% sensitivity and 82% specificity. All the reactives used in the assay were produced in our laboratory.

[Normalization and application of an ELISA ultramicro for the detection of herpes simplex virus antibodies]. / Normalización y aplicación de un ultramicro ELISA para la detección de anticuerpos al virus herpes simple.

An ELISA ultramicro was normalized for detecting herpes simplex virus antibodies. A study was made on 145 samples from the Pedro Kourí Tropical Medicine Institute and the Blood Bank, both by ELISA ultramicro and immunofluorescence and ELISA, and 98% and 99% of coincidence was reached, respectively. It indicates good correspondence between these techniques.

[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.

[Serologic diagnosis of HIV (1988-1989)]. / Diagnóstico serológico del VIH (1988-1989).

Determination of antibodies to HIV virus by the ELISA technique was performed in 27,652 serum samples from January 1988 to November 1989. Samples which were positive twice underwent the Western Blot technique. A 0.41% of positiveness to the virus was found in 1988 and a 0.34% in 1989. Confirmation of positive cases by Western Blot was statistically significant in 1989.

[Comparative study of dengue 2 virus replication and isoenzymes in two strains of Aedes aegypti]. / Etude comparée de la réplication du virus de la dengue 2 et des isoenzymes chez deux souches d'Aedes aegypti.

This study, dealing with two strains of Aedes aegypti from Vietnam and French Guiana, shows the variability of the genes coding for 11 isoenzymatic systems and the replication of the dengue 2 virus in parenterally infected mosquitoes. Slight differences are observed in the characteristics of viral replication. No clear correlation is shown with enzymatic patterns which appear widely different from one strain to the other with four of the enzymes studied.

[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.

[Use of an inhibition method of ELISA in the serologic diagnosis of dengue. Preliminary report]. / Utilización de un método de inhibición de ELISA en el diagnóstico serológico del dengue. Reporte preliminar.

This paper reports the standardization of an ELISA (enzyme-linked immunosorbent assay) inhibition method for the serologic diagnosis of dengue, with the use of non-purified antigen. The conditions and criteria of the test for detection of antibodies for a group of 82 sera (12 monosera and 35 paired sera) are established. The results are compared with those obtained by hemagglutination inhibition and a good agreement between the two tests, as well as greater sensitivity of ELISA, is found. Some advantages of this technique in connection with hemagglutination inhibition are listed; they are: easy performance, rapidity, no need for serum treatment, and the use of viral suspensions without using any method of extraction.

Aislamiento del virus del dengue 2 en sueros de pacientes utilizando el raton lactante y cultivo de celulas LLCMK2. / Isolation of dengue virus type 2 in serum of patients using suckling mice and LLCMK2 cell cultures

El virus del dengue 2 fue aislado en 22 de 40 sueros de pacientes clinicamente diagnosticados como dengue durante la epidemia de dengue hemorragico de Cuba 1981.Se utilizaron como sistemas de aislamientos el raton lactante y las celulas LLCMK2 demostrandose la mayor sensibilidad de estas al obtener 13 aislamientos mas que en raton lactante. Todas las cepas fueron identificadas como dengue tipo 2