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baculovirus

TWiV 571: Piwi koalas

27 October 2019 by Vincent Racaniello

The League of Extraordinary Virologists celebrate the eradication of wild poliovirus type 3, and consider the effectiveness of an influenza vaccine produced in insect cells, and how small RNAs are protecting the Koala germline from retroviral invasion.

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Filed Under: This Week in Virology Tagged With: baculovirus, endogenous retrovirus, Flu, Flublock, Flucelvax, germline, HA, influenza, influenza vaccine, insect cell, Koala, koala retrovirus, piRNA, transposon, viral, virology, virus, viruses

TWiV 548: Mice, shrews, and caterpillars

19 May 2019 by Vincent Racaniello

Vincent travels to the European Congress of Virology in Rotterdam and with local co-host Marion Koopmans speaks with Martin Beer, Stephan Gunther, and Vera Ross about their careers and their work on Lassa virus, Borna virus, and insect viruses.

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Filed Under: This Week in Virology Tagged With: baculovirus, Borna virus, encaphalitis, European Congress of Virology, Lassa virus, metagenomics, nigeria, outbreak response, transplant recipient, viral, virology, virus, virus behavior modification, viruses, zombie caterpillar

TWiV #356: Got viruses?

27 September 2015 by Vincent Racaniello

On episode #356 of the science show This Week in Virology, Stephanie joins the super professors to discuss the gut virome of children with serious malnutrition, caterpillar genes acquired from parasitic wasps, and the effect of adding chemokines to a simian immunodeficiency virus DNA vaccine.

You can find TWiV #356 at www.microbe.tv/twiv.

Filed Under: This Week in Virology Tagged With: adjuvant, baculovirus, bracovirus, caterpillar, chemokine, Cortesia congregata, DNA, dna vaccine, gut virome, horizontal gene transfer, IgA, in vivo electroporation, kwashiorkor, lepidoptera, Malawi, malnutrition, marasmus, mucosal immunity, nudivirus, parasitic wasp, ready to use therapeutic food, rutf, simian immunodeficiency virus, siv, viral, virology, virus

Wasps do a gain-of-function experiment in caterpillars

24 September 2015 by Vincent Racaniello

parasitic waspParasitic wasps (in the order Hymenoptera) inject their eggs into lepidopteran hosts, where the eggs go through their developmental stages. Along with the eggs, the wasps also deliver viruses carrying genes encoding proteins that inhibit caterpillar immune defenses. Some of these genes are permanently transferred to the lepidopteran host where they have assumed new defensive functions against other viruses.

The viruses that parasitic wasps inject with their eggs, called Bracoviruses, are encoded in the wasp genome. About 100 million years ago a nudivirus genome integrated into the genome of a common wasp ancestor. With time the viral genes became dispersed in the wasp genome. The viruses produced by these wasps today no longer carry capsid coding genes – they are found only in the wasp genome – but only carry genes whose products can modulate lepidopteran defenses. Once in the lepidopteran host, these viruses deliver their genes but no longer form new particles.

An important question is whether wasp Bracoviruses can contribute genes to Lepidoptera – a process called horizontal gene transfer. This possibility would seem remote because the lepidopteran hosts for wasp larvae are dead ends – they die after serving as hosts for wasp development. However, it is possible that some hosts resist killing, or that wasps occasionally inject their eggs and viruses into the wrong host, one that can resist killing.

To answer this question, the genome sequence of Cotesia congregata bracovirus was compared with the genomes of a regular host as well as non-host Lepidoptera. Bracovirus DNA insertions were identified in genomes of the monarch, the silkworm, the beet armyworm and the fall armyworm, but not in the genome of the tobacco hornworm, the usual host of the wasp (C. congregata).

Not only were the Bracovirus sequences found in these varied Lepidoptera, but some appeared to be functional. Two such genes encode a protein that interferes with the replication of baculovirus, a known pathogen of Lepidoptera. This discovery was made in the process of producing the encoded proteins using baculovirus vectors! In other words, viral genes delivered by Hymenopteran wasps were appropriated by the Lepidoptera and used for their defense against a pathogen.

To put it another way, nature has carried out a gain-of-function experiment. Should we impose a moratorium?

The delivery of immunosuppressive viruses by wasps along with their eggs is by all accounts a remarkable story. The appropriation of some of these genes by the wrong hosts should not come as a surprise, yet the finding is nevertheless simply amazing. As long as we keep looking, we will find that the biological world is always full of new revelations.

Filed Under: Basic virology, Information Tagged With: baculovirus, bracovirus, butterfly, caterpillar, DNA, horizontal gene transfer, integration, lepidoptera, nudivirus, parasite, parasitic wasp, viral, virology, virus

TWiV 325: Wildcats go viral

22 February 2015 by Vincent Racaniello

On episode #325 of the science show This Week in Virology, Vincent visits the ‘Little Apple’ and speaks with Rollie and Lorena about their work on mosquito-born viruses and baculoviruses.

You can find TWiV #325 at www.microbe.tv/twiv.

Filed Under: This Week in Virology Tagged With: A. aegypti, apoptosis, arbovirus, baculovirus, caspase, caterpillar, insect, metalloproteinase, mosquito, Sindbis virus, transmission, viral, virology, virus

Influenza vaccines for individuals with egg allergy

27 June 2013 by Vincent Racaniello

baculovirusA CDC (US) advisory committee has recommended the use of FluBlok for individuals with egg allergy:

The Advisory Committee on Immunization Practices (ACIP) voted today, 13 to 0, in favor of recommending FluBlok during the 2013-2014 influenza season for vaccination of persons 18 through 49 years of age with egg allergy of any severity.

FluBlok is an influenza virus vaccine that is produced by expressing the influenza virus hemagglutinin (HA) protein in insect cells using a baculovirus vector. Baculoviruses are rod-shaped viruses (see photograph) that infect insects and other arthropods. The baculovirus virion contains a double-stranded DNA genome. To express the influenza virus HA proteins, recombinant baculoviruses are produced in which DNA encoding the HA protein is inserted into the baculovirus DNA genome. When insect cells are infected with the recombinant baculoviruses, the influenza HA protein is produced.

To manufacture FluBlok, three recombinant baculoviruses were isolated  that contain the HA gene from A/Panama/2007/99 (H3N2), A/New Caledonia/20/99 (H1N1), and B/Hong Kong/330/2001. After infection of insect cells with these recombinant baculoviruses, the HA proteins were purified to greater than 95% purity. In a randomized, placebo-controlled clinical trial, FluBlok was shown to be 44.6% effective in preventing culture-confirmed influenza. The low efficacy might in part be due to antigenic mismatch between the HA proteins used in the vaccine and circulating viruses.

Because FluBlok is not produced in eggs it may be used in individuals with egg allergies. Another alternative for such individuals is Flucelvax, an influenza vaccine produced in cell culture, which was approved by the Food and Drug Administration in November 2012.

Filed Under: Basic virology, Information Tagged With: baculovirus, FluBlok, Flucelvax, HA, influenza, insect cell, vaccine, viral, virology, virus

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by Vincent Racaniello

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