TWiV 395: The cancer thief

Vincent, Rich and Kathy speak with Stephen Russell about his career and his work on oncolytic virotherapy – using viruses to treat cancers. Recorded before an audience at ASV 2016 at Virginia Tech in Blacksburg, Virginia.

You can find TWiV #395 at microbe.tv/twiv, or listen/view below.

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TWiV 374: Discordance in B

TWiVOn episode #374 of the science show This Week in Virology, the TWiVniks consider the role of a cell enzyme that removes a protein linked to the 5′-end of the picornavirus genome, and the connection between malaria, Epstein-Barr virus, and endemic Burkitt’s lymphoma.

You can find TWiV #374 at microbe.tv/twiv.

TWiV 359: A Blossom by any other name

On episode #359 of the science show This Week in Virology, Vincent speaks with Blossom about her laboratory’s research on Kaposi’s sarcoma-associated herpesvirus, including how it transforms cells, the switch between lytic and latent replication, and its interaction with the innate immune system of the host.

You can find TWiV #359 at www.microbe.tv/twiv.

TWiV 339: Herpes and the sashimi plot

On episode #339 of the science show This Week in Virology, tre TWiV amici present three snippets and a side of sashimi: how herpesvirus inhibits host cell gene expression by disrupting transcription termination.

You can find TWiV #339 at www.microbe.tv/twiv.

A transmissible cancer of soft-shell clams

Mya_arenariaA leukemia-like cancer is killing soft-shell clams along the east coast of North America. The cancer is transmitted between animals in the ocean, and appears to have originated in a single clam as recently as 40 years ago.

Hemic neoplasm is a disease of marine bivalves that is characterized by proliferation of morphologically and functionally aberrant hemocytes, the cells that circulate in the circulatory fluid of mollusks. A newly identified LTR retrotransposon called Steamer correlates with neoplastic disease in clams. LTR retrotransposons are DNA sequences in the genome that are thought to be precursors to retroviruses. The normal clam genome contains 10-20 copies of Steamer, compared with 150-300 copies in neoplastic hemocytes.

Integration of retroviruses into the genome is a known mechanism for disrupting cellular growth control, leading to uncontrolled proliferation and ultimately development of cancer. Whether Steamer causes neoplasia, by integrating near an oncogene, can be determined based on where this retroelement has inserted in the clam genome.

Analysis of 12 Steamer integration sites revealed that 7 were present in neoplastic samples from clams collected at sites in New York, Maine, and Prince Edward Island, Canada. Examination of nuclear and mitochondrial DNA revealed that cancerous hemocytes collected from clams at all three sites contain similar mutations that are not present in normal tissues. These observations indicate that these neoplasms  are nearly genetically identical and could not have arisen from the hosts. The cancer probably originated in a single clam and was then transmitted to other animals.

Cells from different vertebrates are usually rejected by the host immune system, which recognizes foreign cells by the major histocompatibility (MHC) system. However, mollusks do not have MHC, which may explain why tumor cells can be transmitted among clams. Two other transmissible tumors have been described: the canine venereal tumor, which is sexually passed among dogs, and Tasmanian devil facial tumor disease, transmitted by biting. In both cases MHC molecules are low in tumor cells, explaining why they are not rejected by the recipient animal.

How cancer could spread among clams hundreds of miles apart is not known. Clams are filter feeders, which may lead to uptake of neoplastic cells released into the water by diseased animals. Movement of clams by humans might also have played a role in dissemination of disease along the northeastern US seaboard.

There are no known contagious human cancers, and it is unlikely that the steamer clam neoplasia could be transmitted to humans. It is not known how extensively hemic neoplasia will spread among soft-shell clams, or whether the disease could spread to other bivalves.

TWiV 320: Retroviruses and cranberries

On episode #320 of the science show This Week in Virology, Vincent speaks with John Coffin about his career studying retroviruses, including working with Howard Temin, endogenous retroviruses, XMRV, chronic fatigue syndrome and prostate cancer, HIV/AIDS, and his interest in growing cranberries.

You can find TWiV #320 at www.microbe.tv/twiv.

TWiV 290: Baylor goes viral

On episode #290 of the science show This Week  in VirologyVincent meets up with Janet Butel and Rick Lloyd at Baylor College of Medicine to talk about their work on polyomaviruses and virus induced stress.

You can find TWiV #290 at www.microbe.tv/twiv.

TWiV 264: We should do an all-email show some day

On episode #264 of the science show This Week in Virology, the TWiVites read listener questions and comments about public engagement in science, vaccines, RNAi, reprogramming CD8 cells to treat cancer, rabies, and much more.

You can find TWiV #264 at www.microbe.tv/twiv.

TWiV 218: Monkeys turning valves and pushing buttons

On episode #218 of the science show This Week in Virology, Vincent, Alan, and Welkin discuss how endogenous retroviruses in mice are held in check by the immune response.

You can find TWiV #218 at www.microbe.tv/twiv.

TWiV 163: What Rous wrought

fungal christmas treeHosts: Vincent Racaniello, Dickson DespommierRich Condit, and Alan Dove

Vincent, Dickson, Rich, and Alan review the 100 year old finding by Peyton Rous of a transmissible sarcoma of chickens, a discovery that ushered in the era of tumor virology.

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