Biological and molecular characterisation of coimbatore isolate of papaya ringspot virus

A detailed investigation was carried out on the Coimbatore isolate of Papaya ringspot virus (PRSV) with regard to its transmission, host range and physical properties.Molecular diagnostic tools were also used to detect the virus. Symptoms of papaya ringspot disease included mottling, chlorophyll lobing, filiformity and oily streaks on stem which appeared within 18-22 days of mechanical inoculation. The dilution end point (DEP) and thermal inactivation point (TIP) of the virus was 10^-4 and 45°C, respectively. Longevity of the virus in vitro was 12 h at room temperature (28 + 2°C). Besides papaya (Caricaceae), since the isolate of PRSV produced chlorotic lesions on Cucurbita pepo (Cucurbitaceae) and local lesions on Chenopodium amaranticolor (Chenopodiaceae) it was ascertained as PRSV-P type. Under immunosorbent electron microscopy the virions got decorated with the polyclonal antibodies specific to PRSV. Reverse transcription-polymerase chain reaction (RT-PCR) of symptomatic papaya leaves yielded an amplicon of ~ 850 base pair corresponding to the coat protein gene of the virus.