Detection of Mycobacterium bovis nucleotide sequences from nasal mucus of experimentally inoculated goats

Abstract

EXCRETION OF M. BOVIS THROUGH AEROSOLS AND THEIR INHALATION IS CONSIDERED THE MAIN ROUTE OF TRANSMISSION AND INFECTION IN CATTLE. THE TRADITIONAL METHODS USED FOR MONITORING THE ELIMINATION OF THE MICROORGANISM BY THE NASAL ROUTE ARE THE BACTERIOLOGICAL CULTURE AND THE RADIOMETRIC METHOD. RECENTLY DEVELOPED MOLECULAR BIOLOGY METHODS HAVE FAVORED THE FAST AND RELIABLE DIAGNOSIS OF MYCOBACTERIA IN THE FIELD. IN THE PRESENT WORK, THE M-PCR TECHNIQUE WAS USED TO DETERMINE THE TIME AT WHICH M. BOVIS’ DNA COULD BE DETECTED FROM THE NASAL MUCUS OF 14 EXPERIMENTALLY-INFECTED GOATS. SAMPLES WERE TAKEN FROM THE NASAL CAVITY AT DIFFERENT TIME INTERVALS AFTER THE CHALLENGE, AND BACTERIOLOGICAL CULTURE AND DNA AMPLIFICATION BY M-PCR WERE CARRIED OUT. SIXTY DAYS AFTER CHALLENGE, THE M-PCR TECHNIQUES DETECTED SIX OUT OF 14 ANIMALS AS POSITIVE AND AT DAY 90, THESE SAME SIX ANIMALS PLUS FOUR MORE WERE DETECTED AS POSITIVE. NO SAMPLE WAS POSITIVE TO THE BACTERIOLOGICAL CULTURE. IT IS KNOWN THAT THE BACTERIOLOGICAL ISOLATION OF MYCOBACTERIA IS DIFFICULT AND THAT THE REDUCED NUMBER OF VIABLE BACTERIA IN EACH SAMPLE INFLUENCES THE RESULT OF THE DIAGNOSIS. IN THIS WORK, THE ADVANTAGE OF USING THE M-PCR TECHNIQUE IN ORDER TO OBTAIN POSITIVE RESULTS IN JUST A SHORT TIME WAS DEMONSTRATED, WHICH FAVORS A QUICK AND TIMELY IDENTIFICATION OF THE ANIMALS THAT REPRESENT A RISK OF INFECTION IN THE HERD AND THAT COULD REPRESENT RESERVOIRS OF THE DISEASE.