Plant Virus Laboratory, Floriculture Division, Institute of Himalayan Bioresource Technology, Palampur-176061, Himachal Pradesh.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Coat protein (CP) sequences from 31 geographical isolates of Chrysanthemum virus B (CVB) originating from varied agro-climatic zones of India were determined, analyzed and compared with other isolates from the world. The CP gene of these virus isolates from India showed considerable heterogeneity encoding proteins ranging in size from 306316 amino acid residues. The size of the protein was 315 amino acids except the isolates from Lucknow (Uttar Pradesh, UP), Chennai (Tamil Nadu, TN), Itanagar (Arunachal Pradesh, AR), Dehradun (Uttaranchal, UA) and Sangla (Himachal Pradesh, HP). In these isolates, the protein was variable (deletions) at the N- and C-terminal leading to small sized proteins of length 306 (UA1), 312 (TN, UP, AR), 313 (UA2, HP4) and 316 (HP3). The coat protein of the majority of CVB isolates is characterized by stretch of 6 prolines in the N-terminal. All the isolates had these stretches with the exception of UP isolate in which case the P's were replaced by T at 1–3, 5 and by S at position 6 and only the fourth P was conserved. Further, UP isolate was characterized by 9 unique amino acid residues (SSQQSEQCE) at the C-terminal, while UA1 isolate was having even larger stretch (25 residues, ITMIPSAISTRLSQGGGKDRPFTTI) at the C-terminal. CP showed level of homology ranging from 72–98%. Recombination analysis was carried out with the help of Recombination Detection Program (RDP) and programs therein. Coat protein gene of a number of isolates (namely CHH, HSR, JK3, JK2, UA1, MP, SK, PB, BR, and MH) showed the presence of 36 recombination events. Most of the recombination events (occurring throughout the gene but concentrating on the 5’ and 3’-end and determined by at least three programs) were identified in the UA1 isolate showing 13 events. To our knowledge this is the first report describing the occurrence of recombination in case of carlaviruses.
