Genome organization of Papaya Ringspot Virus isolates from India

Genome of PRSV pathotypes P (10317 nt) and W (10335 nt) from India were completely sequenced. Their genome architecture was similar to other 15 isloates from the rest of the world. Comparative sequence analysis revealed that pathotypes P and W shared high degree of sequence identity both at nucleotide (89%) and aminoacid (94%) levels. Sequence comparison of individual cistrons (except P1) also revealed similar trend. The P1 region was most divergent (upto 33%) and this could be attributed to geographical and host adaptation of PRSV. Cistron by cistron sequence comparison of PRSV pathotypes P and W from India with available 15 sequences and phylogenetic analysis based on full genome polyprotein revealed two distinct groupings of Asian and American isolates, although PRSV India clustered along with the American isolates. Putative recombination sites (24) were available through out the genomes, except in small 6K2 region. Maximum numbers of recombination sites were seen in 5UTR and P1 region and has been speculated to be the most vulnerable region in shaping PRSV genome.