Histopathology of cotton bollworm midgut infected with Helicoverpa armigera cytoplasmic polyhedrosis virus

Abstract

This research was carried out to examine cytopathological effects of Helicoverpa armigera Cytoplasmic polyhedrosis virus (HaCPV) on infected midgut cotton bollworm (Helicoverpa armigera) using transmission and scanning electron microscope. The symptoms on infected host larvae of the host, compared with healthy ones, were getting swollen with milky-white and fragile Histopathological examinations showed infection with HaCPV small polyhedral inclusion bodies (PIB) after 1 or 2 days which were observed in columnar cells of midgut. Virions were partially or completely occupied in a polyhedral matrix to form polyhedral inclusion bodies (PIB) at periphery of virogenic stroma. PIBs were measured 0.5 to 3.5 μm and virions about 46 nm in diameter. Microvilli of infected columnar cells were affected and degenerated immediately prior to rupture of the cell. Some infected columnar cells ruptured to release PIB into the gut lumen 3 days after infection. In addition, PIB were found in goblet cells, 5 or 6 days after infection. Infected goblet cells degenerate to such an extent that only a few of the original microvillus-like cytoplasmic projections and cell organells were left. These cytopathic effects caused in the midgut by HaCPV on cotton bollworm larvae are essentially similar to those have been reported for lepidoperan and dipteran infection by CPV.

A new microbiological weapon against lepidopteran pests

“…The assessment of cumulative mortality of D. sibiricus larvae (main host) revealed that even at a dose as low as 0.5 polyhedrons per larva (i.e., only half of the individuals received a viral inoculum), the virus can kill half of the treated population. This high level of infectivity could be a sequence of high sensitivity of the main host or/and successful horizontal transmission of the virus between individuals owing to the presence of mature occlusion bodies in host feces, as we observed in this study and as reported earlier 21 . The virulence of the new strain, DsCPV1, is much higher than that of another closely related strain, CPV1 (derived from other hosts 7,22 ), and than the virulence of the CPV genus in general 22,23,24,25,26,27 .…”

A New Cypovirus-1 Strain as a Promising Agent for Lepidopteran Pest Control

“…The assessment of cumulative mortality of D. sibiricus larvae (main host) revealed that even at a dose as low as 0.5 polyhedra per larva (i.e., only half of the individuals received a viral inoculum), the virus can kill half of the treated population. This high level of infectivity could be a consequence of the high sensitivity of the main host or/and successful horizontal transmission of the virus between individuals owing to the presence of mature occlusion bodies in host feces, as we observed in this study and as reported earlier ( 23 ). The virulence of the new strain, DsCPV-1, is much higher than that of another closely related strain, CPV-1 (derived from other hosts [ 8 , 24 ]), and higher than the virulence of the CPV genus in general ( 24 – 29 ).…”

Insights into midgut cell types and their crucial role in antiviral immunity in the lepidopteran model Bombyx mori

“…When the larvae of H. armigera were subjected to an infection by the cytoplasmic polyhedrosis virus, a typical pathogen targeting the midgut, a visible deformation in the midgut’s structural architecture emerged. This perturbation was accompanied by the emergence of anomalous microvilli projections subsequent to the viral infection ( 96 ).The GCs, historically linked with mucin secretion and maintenance of epithelial barrier function, might possess a multifaceted role beyond these established functions. The emergence of analogous histological features across diverse taxa sparks the inquiry into the potential conservation of immune functionalities associated with GCs.…”