Effect of thermo therapy on protein profiles of haemolymph of silkworm infected with infectious flacherie virus.

摘要

BmlFV is a non-occluded virus that causes infectious flacherie in silkworm. It is a chronic disease and mortality occurs mainly while spinning the cocoons. Different methods like disinfection of rearing house, development of specific disease tolerant races and thermo therapy have been studied. Earlier, different temperature (25, 27, 30, 32, 35, 37 and 40 degrees C) treatments were utilized as thermo-therapy against infectious flacherie virus and lowest mortality of 21.00-34.67% was observed in high temperature treatment of 37 degrees C compared to inoculated control (65.00%) and other temperature treatments (23.00-46.00%). In the present study, the effect of thermo therapy on total protein content was studied by keeping second instar silkworm larvae at different temperatures for different durations (6 h, 6 h+, 12 h, 12 h+, 24 h and 24 h+) after inoculations with BmlFV. The total protein content was less in the haemolymph of silkworm inoculated with BmlFV and it was 4.45 mg/ml compared to normal control (7.56 mg/ml) and other different temperature treatments (4.52 mg/ml to 7.51 mg/ml). Among the different temperature treatments, high total protein content of 7.05-7.51 mg/ml was observed in the high temperature treatment of 37 degrees C compared to other temperature treatments of 25-35 degrees C (6.06-7.10 mg/ml). The protein profiles of haemolymph of silkworm under different periods of 37 degrees C temperature treatment as thermo therapy against infectious flacherie virus was analysed through SDS-PAGE. The haemolymph of all the silkworms of all the batches had 68 and 29.0 kD protein bands. The haemolymph of healthy silkworms had another two distinct protein bands viz., 16.01 and 17.44 kD between 14.3-20.0 kD protein bands. These bands were not observed in inoculated control and 6 h temperature treatment. However, these bands were appeared in the treatment of 6 h in every instar (6 h+) and in all other treatments (12 h, 12 h+, 24 h and 24 h+) with increased intensity. The intensity of protein bands between 29 to 43 kD in all the treated batches was high when compared to inoculated control. This study suggests that BmlFV infected silkworm larvae can be reared at high temperature treatment of 37 degrees C in each instar for 6 to 12 h for suppression of infectious flacherie as thermal treatment.