Serological detection of close and distant relationships of an isolated Tobamovirus

Abstract

A virus causing mosaic and leaf yellowing symptoms on Mucuna pruriens was isolated and purified through its susceptible host Vigna unguiculata var. TVu 76. Yield of the purified virus obtained was 7.2 mg/kg. It had an ultraviolet (UV) absorption spectrum at 260 nm as 1.53±0.00 and at 280 nm as 1.45±0.00, which translated into nucleic acid content of 72.9 %. Determination of the molecular weight of the virus coat protein from a plotted graph gave 27 kiloDaltons. When the purified virus was electrophoresed in agarose gel, no secondary band was observed. Absorbance curve at 260 nm was obtained when the purified virus was measured spectrophotometrically. A volume of 16 000μL antiserum was obtained against the virus with concentration of 0.3 mg/ml. The titre value determined for the antiserum raised against the virus was 1:2000 as there was a wider difference between the readings obtained for the healthy and diseased controls. At this dilution, the titre value was two and a half times greater than that of the healthy control. The heterologous: homologous percentage (%) obtained for the isolated virus and TMV (Muguga strain) was 50.0 % when Protein-A sandwich enzyme linked immunosorbent assay (PAS ELISA) was used to determine its serological relationship with the virus and other Tobamovirus strains.

Keywords: PAS ELISA, Tobamovirus, coat protein, molecular weight