Immunity: larvae use virus for immunity (Introduction)

by David Turell , Friday, July 30, 2021, 16:00 (1213 days ago) @ David Turell

Larvae using virus genes for parasite protection:

https://www.sciencemag.org/news/2021/07/deadly-viruses-help-moths-and-butterflies-fight...

"Moths and butterflies have long fallen victim to two deadly threats: parasitic wasps and viruses, which battle each other over their lepidopteran hosts. Now, a new study shows some viruses transfer their weapons to infected moths and butterflies, arming them with the genes to make parasite-killing proteins.

"Many species of wasps and flies lay their eggs inside other insects, giving their young a source of food and a safe place to develop—and killing the host in the process. But even though moths and butterflies are favored hosts, some species, including armyworms, cutworms, and cabbage butterflies, have shown a strange resistance to a plethora of wasp parasites, such as Cotesia vanessae and C. kariyai.

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"To find out what was going on, entomologist Madoka Nakai and her team at the Tokyo University of Agriculture and Technology infected northern armyworm larvae with a common pox virus before introducing the immature insects to various parasitic wasp species. Whereas uninfected larvae succumbed to the parasites, the infected larvae—and their plasma—killed almost every parasite, aside from the basket-cocoon parasitoid Meteorus pulchricornis. Researchers then identified two proteins in the infected armyworms, which they called parasitoid killing factor (PKF), that they thought might be toxic to the parasites.

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“'We all arrived at these genes from slightly different directions. Putting our research together created this very interesting story about the biological arms race occurring on a very large scale between multiple pathogens, wasps, and hosts, which we now know are also fighting back,” Theilmann says.

"But the researchers also found an interesting twist—at least one of the PKF-harboring viruses is transmitted to moths and butterflies by the basket-cocoon parasitoid, protecting the very wasp whose larvae can survive its assaults. That suggests that even though PKFs can help the lepidopterans, they may also give an advantage to some parasitic wasps.

"The new work should help researchers understand why moths and butterflies often resist parasitoids used as pesticides for crops and forests, Herrero says. But when it comes to fully understanding the complexity of this evolutionary arms race, many questions are unanswered, Theilmann says. For example, his team still doesn’t know why some viruses have genes for PKF and others don’t. They also don’t know whether all PKFs function in the same manner."

Comment: horizontal gene transfer can come from being infected, which then provides protection in other ways!!! Work in progress. All part of protective designs.