Optical brighteners do not influence covert baculovirus infection of Spodoptera frugiperda

Abstract

Covert infection with Spodoptera frugiperda multiple nucleopolyhedrovirus, detected by reverse transcription-PCR of virus gene transcripts (ie-0 and polh), was not significantly affected by the presence of an optical brightener (Tinopal UNPA-GX), indicating no change in virus virulence. Detection of the covert infection was dependent on insect life stage and the viral mRNA used for diagnosis.

FIG. 1.

(A) RT-PCR fragments amplified with SfMNPV-specific primers for ie-0 from fifth-instar S. frugiperda that survived inoculation with SfMNPV alone (lane 3) or with SfMNPV and Tinopal UNPA-GX (lane 5) in the second instar. (B) RT-PCR fragments amplified with SfMNPV polh primers from fifth-instar S. frugiperda that survived inoculation with SfMNPV alone (lane 3) or with SfMNPV and Tinopal UNPA-GX (lane 5) in the second instar. (C) RT-PCR fragments amplified with SfMNPV polh primers from adults of S. frugiperda that survived inoculation with SfMNPV alone (lane 3) or with SfMNPV and Tinopal UNPA-GX (lane 5) in the second instar. Positive controls (lethally infected larvae) for ie-0 (A, lane 1) and polh (B and C, lanes 1), negative controls (uninfected larvae) for ie-0 (A, lane 2) and polh (B and C, lanes 2), and RNA controls (PCR on total RNA) (A to C, lanes 4 and 6) are shown. Southern blot analyses of the agarose gels shown in panels A to C used labeled SfMNPV ie-0 (D) or polh (E and F) genes as probes. The molecular marker used was 12-kb DNA ladder (Stratagene); fragment sizes are given on the left.