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    Laboratory Services Section
    MC 1947
    PO Box 149347 Austin, TX 78714-9347
    1100 W. 49th Street
    Austin, TX 78756-3199

    Phone: (512) 776-7318
    Fax: (512) 776-7294

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Rabies Diagnosis in Animals

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Fluorescent Antibody Test for Rabies

Touch impressions of brain material are prepared on microscope slides using three parts of the brain:  cerebellum, hippocampus, and brain stem. The slides are fixed in acetone for at least one hour. Next, the slides are stained using a fluorescein labeled antibody specific for rabies virus, which is diluted in a normal rabbit brain suspension, and incubated with the antibody for 30 minutes. They are then washed in PBS two times, for five minutes each, dipped in distilled water, and air-dried. The slides are mounted with buffered glycerol, pH 9.0, and examined using an epifluorescent microscope. Positive and negative control slides are included with each run.


Monoclonal Typing of Rabies Isolates

Rabies positive specimens are tested using an indirect fluorescent-antibody procedure with a panel of 19 monoclonal antibodies. Acetone fixed touch impressions of brain material or infected cell culture monolayers are stained with each of the monoclonal antibodies for 30 minutes at 37° C, washed to remove unbound antibody, and stained with fluorescein-conjugated goat antibody to mouse IgG. The slides are mounted with buffered glycerol, pH 9.0, and examined using an epifluorescent microscope. The rabies variants are characterized based on patterns of reaction with the panel of monoclonal antibodies.

Molecular Characterization of Rabies Isolates

Rabies Molecular Typing

Rabies molecular typing procedures (RNA Extraction, Reverse Transcription, Polymerase Chain Reaction, and Nucleotide Sequencing) are used to differentiate between rabies variants that are inconclusive or indistinguishable by monoclonal typing (e.g. Texas fox and domestic dog/coyote variants). Basic Local Alignment Search Tool (BLAST) is used to compare sequence data to sequences in GenBank to determine the closest matches (most closely related variants) and likely source of the rabies virus.

Monoclonal Typing Patterns of Terrestrial Rabies Strains Found in Texas

 

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South Central skunk

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Texas fox/Domestic dog/coyote, Sonora dog

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Hog-nose skunk

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Monoclonal Typing Patterns of Bat Rabies Strains

 

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Tadarida brasiliensis 

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Lasiurus borealis, Lasiurus seminolus 

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Nycticeius humeralis 

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Last updated October 17, 2014