Fluorescent Antibody Test For Rabies Research Articles

Severe Neurologic Disease in a Horse Caused by Tick-Borne Encephalitis Virus, Austria, 2021.

As evidenced by sero-epidemiological studies, infections of horses with the tick-borne encephalitis virus (TBEV) occur frequently in TBEV-endemic areas. However, there are only very few reports of clinical cases. A possible underreporting may be due to a variety of diagnostic challenges. In this study, ELISA and neutralization tests were applied to serum samples. Brain tissue samples were investigated for the presence of nucleic acids of TBEV, Equid alphaherpesvirus 1, Borna disease virus 1, West Nile and Usutu viruses, rustrela virus, as well as Eastern, Western, and Venezuelan equine encephalitis viruses with RT-qPCR, RT-PCR, and qPCR, respectively. TBEV-specific amplification products were subjected to Sanger sequencing. In addition, a direct fluorescent antibody test for rabies was performed. Clinical and patho-histological findings are reported. Using specific RT-qPCR and RT-PCR assays, TBEV nucleic acids were demonstrated in brain tissue samples. Sequencing revealed the Western (formerly Central) European subtype of TBEV as the etiological agent. A high titer of TBEV-specific neutralizing antibodies was found in the serum. RNAscope in situ hybridization revealed TBEV RNA confined to neuronal cell bodies and processes. No other pathogens or nucleic acids thereof could be detected. Diagnostic procedures need to be carried out early after the onset of neurological signs to allow for a final etiological diagnosis of acute TBEV infections in horses.

Sero-diagnostic studies on the occurrence and prevalence of bovine spongiform encephalopathies in Nasarawa state, Nigeria

The study was conducted to determine the occurrence and the prevalence of bovine spongiform encephalopathy among cattle herds in Nasarawa State, Nigeria using targeted sampling approach. The procedure of sampling adapted was a “double” targeted method for survey. First, a BSE risk group was targeted ‘emergency or casualty slaughter’ and within this Group, animals with signs indicative for BSE were sub-targeted. Two sampling locations were chosen; Akwanga central abattoir and Lafia central abattoir, both located in Nasarawa North and Nasarawa south senatorial district. Immediately the suspected animals were slaughtered, the caudal brain stem was harvested and examined for the disease specific form of the prion protein, PrPSc, using Western Blot technique after proteinase K digestion. A total of 2000 cattle of local breeds, aged ≥ 24 months and above were clinically examined. A total of 147 (7.4 %) of the cattle sampled were clinically suspicious for BSE. No sample was positive for BSE. Fluorescent antibody test for rabies and H&E staining on samples were carried out to observe for differential diagnosis. These showed no pathological lesions indicative for neurological disease. While our findings do not exclude the presence of BSE in Nasarawa State, we demonstrate that targeted sampling of ruminants for neuroinfectious disease is possible in developing countries, pointing to the possibility of implementing such a monitoring scheme in Nigeria to prevent economic losses in ruminant livestock as BSE caveats from endemic countries have shown.

A Targeted Survey for Scrapie in Jos Plateau State, Nigeria.

Scrapie, a disease of sheep and goats with a progressive course and fatal outcome, has not been identified in Nigeria. Anecdotal scrapie reports by livestock workers abound. Livestock diseases like scrapie form huddles in livestock economics of countries. For 8 months we surveyed for scrapie targeting emergency/casualty slaughter sheep and goats in Jos, Nigeria. We clinically examined 510 sheep and 608 goats of local breeds, aged from 12 months to 5 years. In total 31 (5.10%) goats and no sheep were clinically suspicious for scrapie. Caudal brainstem tissues of suspect animals collected postmortem were analyzed for the disease specific form of the prion protein, PrPSc, using Bio-Rad's TeSeE ELISA rapid test kit. No sample was positive for scrapie. Fluorescent antibody test for rabies and H&E staining on samples were carried out for differential diagnosis. These showed no pathological lesions indicative for neurological disease. While our findings do not exclude the presence of scrapie in Jos, we demonstrate that targeted sampling of small ruminants for neuroinfectious disease is feasible in developing countries, pointing to the possibility of implementing such a monitoring scheme in Nigeria to prevent economic losses in small ruminant livestock as scrapie caveats from endemic countries have shown.

Aspectos clínico-patológicos e imuno-histoquímicos de equídeos infectados pelo vírus da raiva

Foram analisados 14 equídeos (13 equinos e 1 muar) com diagnóstico clínico e histológico de raiva provenientes de quatro regiões do Brasil. O curso clínico médio foi de quatro dias de evolução, incluindo incoordenação motora, paralisia dos membros pélvicos, paresia dos membros torácicos e decúbito. Os achados histopatológicos caracterizaram-se por meningoencefalite e meningomielite não supurativa com infiltrado perivascular linfoplasmocitário. Corpúsculos de Negri foram observados em 64,28% (9/14) dos casos, principalmente na medula espinhal cervical e nos neurônios de Purkinje do cerebelo. Em 55,55% (5/9) dos equídeos analisados tiveram resultado positivo pela técnica de imunofluorescência direta para raiva. Todos os casos foram positivos na imuno-histoquímica para raiva, cujas reações foram mais evidentes no córtex temporal, córtex occipital e medula espinhal cervical. A técnica de imuno-histoquímica foi essencial para confirmar todos os casos de raiva nos equídeos.

Imported Human Rabies, the Philippines and Finland, 2007

Imported Human Rabies, the Philippines and Finland, 2007

Fluorescent antibody test for rabies: prospective study of 8,987 brains.

A prospective study of 8,987 canine, feline, human, and other mammalian brains (and one avian brain) was undertaken. The brains were analyzed for rabies antigens; two samples were obtained from each brainstem, and one sample was obtained from each hippocampus. The samples were stained with rabies conjugate and examined by use of fluorescence microscopy. There were no false-negative results. We conclude, therefore, that postexposure rabies treatment is not requisite in all cases, provided that the fluorescent antibody test is performed without delay in a laboratory experienced with the procedure and microscopy results are fluorescent negative.

Morphologic and immunoperoxidase study of neurologic lesions in naturally acquired rabies of raccoons.

Histopathologic (hematoxylin and eosin [HE]) and immunoperoxidase (streptavidin-biotin complex) methods were used for examination of formalin-fixed tissues of rabid raccoons from an enzootic area of Pennsylvania. Extensive morphologic lesions of rabies encephalitis were present in the cerebrum and the brain stem regions. Negri bodies were detected by both methods and were present in the brain (cerebral cortex, hippocampus, brain stem, cerebellum, and cervical spinal cord) and in the ganglia of the trigeminal nerves. The viral inclusions were also seen in ganglion cells in the tongue, parotid salivary glands, pancreas, intestines, and adrenal glands. These sites were not associated with any inflammatory cellular infiltrate. The immunoperoxidase method was superior to HE for the detection of Negri bodies. Because lesions of rabies encephalitis were consistently observed in the cerebrum, brain stem, and cervical spinal cord regions, these areas of the brain should be included when raccoons are examined by the fluorescent antibody test for rabies.

RABIES IN A PRONGHORN ANTELOPE, Antilocapra americana

A ten week old antelope died from rabies 35 days after being bitten on the left hock by a skunk. The result of the direct fluorescent antibody test for rabies was positive.

Diagnosis of human rabies by the cornea test.

The second death due to rabies encephalitis occurring among American servicemen stationed in the Republic of Vietnam is reported. The clinical diagnosis was confirmed by performing the direct fluorescent antibody test for rabies on smears of corneal epithelial cells obtained on the second day of hospitalization. The reliability of various laboratory procedures in confirming the diagnosis of human rabies early in the course of clinical illness is discussed. The cornea test is a useful and rapid method of diagnosing human rabies prior to the development of significant serum antibody titers.

Standardization and quantitation of immunofluorescence in the rabies fluorescent-antibody test.

The standardization and quantitation of immunofluorescence with a Farrand microphotometer in the rabies fluorescent-antibody technique were determined. The system is useful in maintaining the quality of examinations for rabies in a public health laboratory since quantitation of reagent, equipment performance, and specificity of reaction can be evaluated. An analysis of the results demonstrates the high degree of reproducibility and the accuracy of the techniques described.

Standardization and Quantitation of Immunofluorescence in the Rabies Fluorescent-Antibody Test

The standardization and quantitation of immunofluorescence with a Farrand microphotometer in the rabies fluorescent-antibody technique were determined. The system is useful in maintaining the quality of examinations for rabies in a public health laboratory since quantitation of reagent, equipment performance, and specificity of reaction can be evaluated. An analysis of the results demonstrates the high degree of reproducibility and the accuracy of the techniques described.

Some aspects of fixation in the fluorescent antibody test for rabies.

Smears of rabid murine brain were fixed in acetone, ethanol or methanol, subject to variations in time or temperature, before being submitted to the fluorescent antibody test for rabies. Other smears were heat fixed or nor fixed at all. Only acetone fixation, either at room temperature or −20°C, for as short a time as 15 minutes or as long as 20 hours, gave consistently satisfactory results in staining.

The storage life of biological reagents used in the fluorescent antibody test for rabies

Three systems of storing fluorescein-conjugated antirabies globulin and mouse brain suspensions were investigated to find their effect on the reliability of the fluorescent antibody test for rabies. Premixed conjugate and mouse brain suspension, dispensed in test aliquots and maintained at −20°C until required, gave the most consistent results. After 9 months' storage the reagents gave a satisfactory test with known positive smears.

Inactivation of the mouse brain suspension used in the fluorescent antibody test for rabies.

An attempt was made to inactivate rabies virus in the rabid mouse brain suspension used in the fluorescent antibody test for rabies, by incubation with beta-propiolactone, at a dilution of 1 in 100 or 1 in 1000, or formaldehyde at a dilution of 1 in 200 or 1 in 1000. Each reagent at each dilution inactivated the suspension; but only beta-propiolactone diluted 1 in 1000 had no adverse effect on the working of the test.