Virology

Biography

Biography: Y.S.Ahlawat

Abstract

As the name indicates, Indian citrus ring spot disease was originally reported from India and so far it is restricted to India. Field affected trees show typical yellow rings in most of the leaves. The incidence of the disease ranged from 5-83.8% and a yield loss was estimated from 20.5 to 98.38%. Natural infection of Indian citrus ring spot virus (ICRSV) was observed in sweet oranges, mandarins, limes and lemons. ICRSV is transmitted by grafts and by mechanical inoculation from citrus to herbaceous hosts like Chenopodium amaranticolor, C. quinoa, French bean, soybean, cowpea and Vicia faba major. No vector is known but virus particles were observed in pollen grains. A filamentous virus of 650 x 13 nm with clearly visible cross banding was associated with the disease. Indian citrus ring spot virus is the only current member of the genus Mandrivirus in the family Flexiviridae. ICRSV genome is positive sense single stranded RNA of about 7.5 kb without poly-A tail and with a coat protein of 34kDa. ICRSV have 6% nucleic acid. The viral genome was fully sequenced which consists of 7560 nucleotides. It contains 6 open reading frames (ORFs) which encode putative proteins of 187.3, 25,12, 6.4, 34 kDa respectively. Function of ORF 6 is unknown which differentiate ICRSV from Potexviruses.. ICRSV was detected in ELISA, ISEM, DIBA, Nucleic acid hybridization, Western blotting and RT-PCR. The virus can be eliminated by shoot tip grafting and replacing infected trees with healthy plants.