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The Viruses
Published in Julius P. Kreier, Infection, Resistance, and Immunity, 2022
A filterable agent was demonstrated to transmit human warts in 1907. Occasionally warts may become malignant. In the 1930s Shope demonstrated that myxoma virus, a papilloma-inducing virus of rabbits, could cause malignant squamous cell carcinoma. He showed that domestic rabbits infected with myxoma virus developed malignancy more frequently than did wild cottontail rabbits and that topical application of certain chemicals increased the incidence of malignancy. Thus, both host genetic factors and environmental agents were shown to act as cofactors in the development of the virus induced malignancy.
Experimental Oral Carcinogenesis
Published in Samuel Dreizen, Barnet M. Levy, Handbook of Experimental Stomatology, 2020
Samuel Dreizen, Barnet M. Levy
The story of the virus etiology of malignant disease is an interesting and complex one. Shope68 of the Rockefeller Institute, who was a great hunter, shot a rabbit with tumors under the skin of the front and hind legs. He was able to transmit the tumor by the use of a cell-free extract, indicating a viral etiology. The tumor did not kill the animal and eventually regressed. The virus was later shown to be mosquito-transmitted and related to the myxoma virus. Later, Kilham69 showed that he could transform a rabbit fibroma virus into a myxoma virus by adding heated myxoma virus to live fibroma virus. The resulting lesion was a myxofibroma, a viral-induced tumor of rabbits still used in the study of viral oncogenesis. He also showed70 that a fibroma of the grey squirrel could be transmitted by a cell-free extract and that this virus-induced tumor also had a mosquito vector.
Fleas (order Siphonaptera)
Published in Eric S. Loker, Bruce V. Hofkin, Parasitology, 2015
Eric S. Loker, Bruce V. Hofkin
Hosts and transmission Although they often have preferred hosts, most fleas are not highly host specific, readily transferring between hosts of different species. For instance, the cat flea C. felis readily uses both cats and dogs, as well as humans and other mammals as hosts. Various flea species transmit a variety of viral, bacterial, and eukaryotic parasites. The most important flea-borne disease is bubonic plague, caused by the bacterium Yersinia pestis. The most important vector species is probably the oriental rat flea Xenopsylla cheopis, but other species, including Pulex irritans, the human flea, are capable of transmitting plague. Rickettsia typhi, the bacterium responsible for murine typhus, is transmitted by several flea species. Myxoma virus, a pathogen in rabbits, is transmitted by several arthropods including fleas. C. felis, C. canis, and P. irritans all serve as intermediate hosts of the tapeworm Dipylidium caninum (see page 459). Trypanosomes in the subgenus Herpetosoma, and tapeworms in the genus Hymenolepis may also be vectored by fleas.
Cross-testing of direct-action antivirals, universal vaccines, or search for host-level antivirals: what will sooner lead to a generic capability to combat the emerging viral pandemics?
Published in Expert Review of Anti-infective Therapy, 2022
This cross-testing would involve about 700–1000 DAA compounds that passed Phase I trials or higher in humans or domestic animals. This number follows the list of approved DAA antivirals for human and veterinary use, and accounts for both approved agents and precursors. These compounds need to be tested against each taxonomic family. For example, Poxiviridae includes smallpox virus, cowpox, myxoma virus, monkeypox, vaccinia virus. Choosing the safest member and testing the entire DAA panel will identify the best 3–4 hits that can be re-tested against more dangerous cousins in the same taxon. The screens can be prioritized to cover the families that are most likely – based on the historical record – to produce the next emergent pandemic. We argue (in Supplemental Material) that the diseases lightheartedly termed ‘common colds’ are caused by a diverse group of pathogens with a clear epidemic potential (due to air-born or effective fomite transmission), but that display abortive course, limited to the non-systemic symptoms – hence is the complacency [18–21]. The term ‘common colds’ is obsolete since it detracts from the urgency to address these pathogens. To emphasize the latter, both coronaviruses and influenza are classified in this group.
Advances in viral oncolytics for treatment of multiple myeloma – a focused review
Published in Expert Review of Hematology, 2021
Ayesha Sarwar, Laila Hashim, Muhammad Salman Faisal, Mobeen Zaka Haider, Zahoor Ahmed, Tehniat Faraz Ahmed, Moazzam Shahzad, Iqraa Ansar, Sundas Ali, Muhammad Muaaz Aslam, Faiz Anwer
Certain viruses have shown oncolytic properties, these viruses can be genetically engineered and directed to recognize tumor cells using various cell surface receptors and achieve tumor apoptosis. These include Bovine virus, Myxoma virus, Mengovirus, Adenovirus, Measles virus, Vaccinia virus, Reovirus, Vesicular-stomatitis virus, and Coxsackie viruses. Oncolytic viruses can be used in conjunction with pharmacological therapy to induce remission in multiple myeloma patients. These viruses have been studied in preclinical trials and have initial promising results except the Mengo virus, whose results are largely negatively affected by the toxicity profile. Measles virus, Vesicular-stomatitis Virus, and Reovirus are undergoing clinical trials with or without conventional pharmacological regimes. However, oncolytic viruses are still far from being introduced into standard clinical practice.
Platelets and extracellular traps in infections
Published in Platelets, 2021
Ricardo M Gómez, Aída O López Ortiz, Mirta Schattner
While several studies showed a role for platelets in bacteria-induced NETs, little information is available regarding the role of platelets in NETs formation triggered by viruses. Jenne et al., observed the presence of NETs in mice challenged with poly IC or the rabbit myxoma virus. However, they also found that platelet accumulation on the adherent neutrophils in the liver sinusoid were critical for NETs formation and for the host viral response, as they capture viruses, and thereby protecting host cells from further viral dissemination [113]. Interestingly, in vitro NETs induction with neutrophils and platelets from SIV-infected macaques resulted in a significant capture of platelets in the NETs, and it was suggested that this phenomenon could explain not only the thrombocytopenia but also the high risk of cardiovascular events observed in human/simian immunodeficiency virus (HIV/SIV)-infected subjects/non-human primates [112].