Indian Journal of Virology

Polyphenolics from plant tissues are implicated in the inhibition of viral nucleic acid release and reverse transcription polymerase chain reaction (RT-PCR). A protocol has been developed for the release of Banana bract mosaic virus from infected stem and bract which are rich in phenolics. The method enabled RNA extraction and RT-PCR to amplify the coat protein (CP) gene and 3’ untranslated region (UTR) of two Indian isolates of BBrMV, one from stem (Coimbatore isolate) and the other from bract (Dharwad isolate). The PCR products from Coimbatore isolate were cloned, sequenced and it had 1062 nucleotides including 900 coding for the CP gene and a 5’ 162 nucleotides of the 3’ UTR. The CP-coding region had a Hind III internal restriction site with which the orientation of the insert within the recombinant vector was identified that was further confirmed in sequencing. The nucleotide sequence of the CP-coding region of the isolate was compared with the other Indian isolates of Genbank and variability of 1.0% to 4.6% and 0.7% to 2.0% was noticed between the isolates at nucleic acid and amino acid levels respectively. Variability between our isolate and that from four other southeast Asian isolates ranged from 4.5% to 5.3% at nucleic acid and 1.4% to 3.0% at amino acid levels respectively. A set of primers has also been designed to amplify a smaller 699 bp product of the CP-coding region to identify the pathogen from infected tissues. This forms the first report of the molecular characterization of BBrMV from stem and bract of banana.