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Polydnaviruses of hymenopteran endoparasitoids knock out the host insect immune response

100%

Glinski Z., Jarosz J.

The insect immune system reacts against invading microorganisms and parasites with the recruitment of haemocytes and with humoral response. Cellular immune reactions involve phagocytosis, nodule formation and encapsulation by different types of haemocytes whereas insect cell-free antibacterial immunity depends on the production of a number of peptides and proteins, among which lysozyme, cecropins and attacins represent the major group of immune proteins. Polydnaviruses from certain hymenopterous parasitoids interfere with both host immunity and host development. These immunosuppressive viruses exhibit an intimate genetic relationship with the parasitoid since viral sequences are integrated within the parasitoid chromosomal DNA. The viral genes expression in parasitized host induces immunosuppression and alters development of the host insect. The parasitoids developing in the host body cavity knock out the insect immune system, inducing a decline in cellular and humoral components of the immune system so that parasitoid eggs are not recognized as foreign and thereby are not encapsulated. Polydnaviruses carrying parasitoids escape the host immune response and may develop within the insect host whereas other invaders are normally destroyed by defense factors of insect haemolymph.

Exoproteinases of the type A in pathogenesis of insect bacterial diseases

88%

Andrejko M.

Folia Biologica

1999

vol. 47

issue 3-4

135-141

Immune inhibitors produced in infected larvae of Galleria mellonella by such entomopathogens as Pseudomonas aeruginosa, Serratia marcescens and Heterorhabditis bacteriophora effectively blocked in vitro bactericidal activity of insect haemolymph against Escherichia coli D31, both in Galleria mellonella and Pieris brassicae pupae previously vaccinated with Enterobacter cloacae. Even at a trace concentration, the extracellular proteinases, by proteolytic degradation, totally destroyed the activity of cecropin peptides from Galleria and cecropin-like and attacin-family proteins from Pieris, but no ability to destroy antibacterial activity was shown by extracts obtained from Galleria larvae killed by massive doses of bacterial saprophytes. It is suggested that by blocking antibacterial immune response of the host, the proteinases help the bacteria to multiply in the haemolymph, thus they could be considered an important factor in the pathogenesis of bacterial diseases of insects.

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2 Folia Biologica

1 1999

1 1996

1 Andrejko M.

1 Glinski Z.

1 Jarosz J.

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Polydnaviruses of hymenopteran endoparasitoids knock out the host insect immune response

Exoproteinases of the type A in pathogenesis of insect bacterial diseases