Sensibilidade da técnica de imuno-histoquímica em fragmentos de sistema nervoso central de bovinos e equinos naturalmente infectados pelo vírus da raiva

Abstract

Rabies is a viral zoonosis that causes disease in the central nervous system (CNS) of mammals and it is considered a serious problem of public health. Herbivorous (bovines and equines) are often infected after being attacked by vampire bats (Desmodus rotundus). The direct fluorescent antibody technique is used as a diagnostic test to detect viral antigens in fresh tissues and is recommended by the World Health Organization. The immunohistochemistry technique (IHC) is used to detect the viral antigen through the use of monoclonal/policlonal antibodies in formalin-fixed tissues. The aim of this work was to evaluate the sensitivity of the IHC in samples of CNS of herbivorous fixed in formol, analyzing the antigenic distribution in different fragments of the CNS. The results demonstrated good agreement between the two techniques for the rabies diagnosis. The IHC presented higher sensitivity in samples of cattle comparing to horse samples, especially in fragments of cerebellum and brain stem. These fragments demonstrated to be more suitable for antigen detection by both techniques in the two species. These data demonstrate that the IHC is suitable for rabies vigilance yet cautions should be taken in examining cattle and horses samples, when the submitted specimen is only the hippocampus.INDEX TERMS: Rabies, immunohistochemistry, direct fluorescent antibody test, sensitivity, herbivorous.

In situ histopathological and immunohistochemical characterization of rabies in the brains of naturally infected equines and bovines

“…This is a higher figure than in other studies, in which the corresponding figure was 47% (Green et al, 1992;Lima et al, 2005;Peixoto et al, 2000;Carrieri et al, 2006). The greatest amount of viral antigen was observed in the cerebellum and brainstem regardless of the technique used (FAT or IHC), agreeing with the findings of previous studies (Langohr et al, 2003;Pedroso et al, 2009, Achkar et al, 2010. For bovine brain samples in paraffin embedded tissue, IHC was more sensitive than FAT.…”

“…In the equine samples, the technique was more sensitive when used with cerebellum and brainstem samples. These findings confirm that IHC is a suitable alternative technique for laboratory diagnosis of rabies when FAT cannot be used and it is particularly useful for equine samples as FAT can yield many false negative results with this type of sample (Achkar et al, 2010).…”

“…Studies have shown that the incubation period of the virus from herbivore samples inoculated in mice varies from 7 to 13 days (Silva et al, 2010;Achkar et al, 2010). Here, the virus was isolated in 75% of the samples, and the incubation period varied from 7 to 14 days.…”

“…For the immunohistochemical analysis (IHC), peroxidase-labeled streptavidin/biotin-complex (SABC) and anti-rabies polyclonal antibody provided by the Evandro Chagas Institute, Belém, PA, were used (Bourgon & Charlton, 1987;Achkar et al, 2010;Fernandes et al, 2011). The IHC reaction was assessed using positive controls (brain fragments containing rabies virus antigen) and negative controls, which had all the reagents except the polyclonal antibody.…”

Doenças do sistema nervoso de bovinos no Mato Grosso do Sul: 1082 casos

“…Esses resultados corroboram com os relatos de outros autores que descrevem correlação entre a sensibilidade diagnóstica das diferentes técnicas (Pedroso et al 2009, Achkar et al 2010, Stein et al 2010, Marcolongo-Pereira et al 2011. Em outros quatro casos a IFD foi negativa e a IIC e IHQ positivas.…”