Transcriptome of Bombyx mori (2nd Instar) transovarial infected with Nosema bombycis

Nosema bombycis infection causes a devastating ailment known as pebrine disease in silkworms. Majority of the infection is through feeding of N. bombycis contaminated leaves and can also be vertically transmitted to the next generation through eggs laid by an infected female moths, which is known as transovarial infection. Infection results in sluggish movement and developmental defects as the larvae finally succumbs to secondary bacterial infection. Microscopic examination of body fluids reveals the presence of oval spores at an advanced stage of infection. However, diagnosis of transovarial infection at an early stage is quite challenging as the larvae appears healthy and similar to uninfected larvae. Usage of present diagnostic techniques in detection of infection like Polymerase Chain Reaction (PCR) demands technical expertise and knowledge which is lacking in the socio-economic group of farmers. To mitigate this issue a simple diagnostic technology with easy usability and adequate affordability needs to be designed which is only possible through the identification of biomarkers for early detection of pebrine disease. To identify these biomarkers we did transcriptome sequencing and analysis of Nosema infected 2nd instar larvae of Bombyx mori and observed that infection caused activation of IMD pathway which shows a potential immune defense response against pebrine infection as well as suppression of melanin synthesis pathway due to lower expression of PPAE converting enzyme. Moreover, through differential expression analysis of the transcriptome data we found that antigen LPMC-61, Yellow-y, Gasp and Osiris 9 can be utilized as a potential marker for early diagnosis of transovarial pebrine infection in Bombyx mori.