Diagnóstico inmunohistoquímico del dengue en cortes de parafina

Abstract

In our country it is frequently necessary to confirm the presence of dengue viruses in tissue taken from patients suffering from hemorrhagic dengue and, particulay, in those cases where no other test is available to confirm viral etiology. Therefore, we are standardising an immunohistochemical technique to detect dengue antigens in paraffin fixed tissue. We used anti-flavivirus antibodies commonly used in serological diagnosis. The antigens used in this technique include: 1) rats' brains innoculated with different dengue serotypes and with yellow fever virus; 2) liver sections taken from patients diagnosed as suffering from hemorrhagic dengue, yellow fever or hepatitis delta; and, 3) C6136 single-layer cells also innoculated with different dengue serotypes. These antigens were confronted by anti-flavivirus antibodies (yellow fever ordengue) prepared from rats as immune ascitic liquids (IAL), :ollowing already established procedures. We used IAL prepared in the INS and, also, IAL supplied by PAHO. The ideal dilution in which it is possible to observe the antibodies' presence, in both the tissue as well as the cells, was obtained by titering the distinct IAL to confront the deparaffined tissue orto confront cells mounted on glass microscope sections, fixed in ethanol. With IALprepared in the INS weobserveacross-reaction amongsttheflavivirus, a result which was not observed in the liver sections from patients diagnosed as having hepatitis delta. Results obtained from the IAL provided by PAHO allowed clearerviewing of viral antigens and greater dilution without the cross-reaction between dengue and yellow fever. However, viewing the same using IAL form the INS is satisfactory and this source of IAL is permanently available. The cross- reaction between the dengue and the yellow fever virus is nota major problem in tissue because the histopathology of the two entities, in the liver, is vey different.