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Evolution
Published in Paul Pumpens, Single-Stranded RNA Phages, 2020
Much later, the evolution of tertiary structure of a long list of the viral RNA-dependent polymerases including the Qβ replicase was studied by Černý et al. (2014). The authors stated that the sequence similarity of the enzymes was too low for the phylogenetic studies, although general protein structures were remarkably conserved. The major strength of this work consisted of the unification of the sequence and structural data into a single quantitative phylogenetic analysis, using the powerful Bayesian approach. The resulting phylogram of the enzymes demonstrated that the RNA-dependent DNA polymerases of viruses within the Retroviridae family clustered in a clearly separated group, while the RNA-dependent RNA polymerases of double-stranded and single-stranded RNA viruses were mixed together. This evidence supported the hypothesis that the enzymes replicating the single-stranded RNA viruses evolved multiple times from the enzymes replicating the double-stranded RNA viruses, and vice versa. The authors recommended their phylogram as a scheme for the general RNA virus evolution. This phylogenetic tree of the evolution of the RNA-dependent polymerases and possibly of the RNA viruses is shown in Figure 18.6.
Classes of Compounds with GI Tract Toxicity
Published in Shayne C. Gad, Toxicology of the Gastrointestinal Tract, 2018
Amy L. Mihalchik, Erica N. Rogers
In 1998, the United States Food and Drug Administration (FDA) licensed vaccine known Rotashield® which was marketed to prevent rotavirus in infants and young children. Rotavirus is the leading cause of viral gastroenteritis (severe vomiting and diarrhea) in children between the ages of 3 months and 5 years worldwide. The exact mechanism of action exerted by natural rotavirus infection is incompletely understood. However, this virus is suggested to be primarily transmitted by the fecal-oral route, and can last on human hands for hours, days on inanimate surfaces, and resist common disinfectants (Bernstein, 2009). This infection is characterized as a collection of non-enveloped segmented double-stranded RNA viruses from the Reoviridae family. Most of the human rotavirus infections are the result of exposure to group A viruses (Pasetti et al., 2011). The outermost layer of the viral nucleocapsid of rotaviruses is composed of two viral surface proteins, VP4 (protease sensitive, P serotypes) and VP7 (glycoprotein G serotypes). Administration of the rotavirus vaccine, Rotashield™, induces antibodies which target the neutralization of these serotypes in rotavirus strains (Payne et al., 2016). In addition, use of Rotashield® was advantageous based on its capability to replicate less efficiently in the human intestines when compared to natural human rotaviruses and protect against the challenge, controlled strain.
Spontaneous Insulin-Dependent Diabetes Mellitus (IDDM) in Nonobese Diabetic (NOD) Mice: Comparisons with Experimentally Induced IDDM
Published in John H. McNeill, Experimental Models of Diabetes, 2018
Edward H. Leiter, Ivan C. Gerling, Jeffrey C. Flynn
Among the various human viruses adapted for growth in mouse cells are the RNA-containing picornaviruses Coxsackie B4 (CB4), encephalomyocarditis (EMC-D and M variants), and Mengo-2T, as well as two other double-stranded RNA viruses, reovirus and lymphocytic choriomeningitis virus (LMCV, Armstrong variant). Primary isolates of these human pathogenic agents are generally not pancreatotrophic or lytic to mouse β-cells and must be adapted for growth either by inoculation into suckling mice, or by passage in cultured mouse β-cells. The picornaviruses adapted for growth in mice are primarily tropic for pancreatic exocrine and myocardial tissues, but tropism of picornavirus and reovirus for β-cells can be increased by serial passage in primary cultures of mouse embryonic fibroblasts or islet cells.201
Oncolytic virus therapy for malignant gliomas: entering the new era
Published in Expert Opinion on Biological Therapy, 2023
Hirotaka Fudaba, Hiroaki Wakimoto
Poliovirus is a single-stranded RNA virus of the Piconaviridae family. CD155, a type 1 transmembrane glycoprotein and a member of the nectin-like family, serves as the cellular receptor for poliovirus. Reovirus is a double-stranded RNA virus of the Reoviridae family. Reolysin is a Dearing type 3 strain virus, which replicates in Ras mutant cells. Measles virus (MV) is a single-stranded, a negative-sense RNA virus of the Paramyxoviridae family. MV-CEA is an attenuated strain of measles virus (MV), derived from the Edmonston vaccine lineage, genetically engineered to produce carcinoembryonic antigen (CEA), which has demonstrated efficacy against GBM in preclinical studies [8–10]. Newcastle disease virus, a negative-sense, single-stranded RNA virus, was previously studied clinically in GBM, sarcoma, and neuroblastoma, but no clinical trial has been active since 2015.
Oncolytic viruses: how “lytic” must they be for therapeutic efficacy?
Published in OncoImmunology, 2019
Maria Eugenia Davola, Karen Louise Mossman
Reovirus is a naturally occurring, non-pathogenic double-stranded RNA virus, with selective toxicity toward cells with an activated Ras pathway.67,68 Reovirus is under investigation in phase I and II clinical trials and is considered a potential candidate for phase III trials.69 Although viral life cycles of RNA viruses differ significantly with those of DNA viruses, antitumor activity of reovirus type 3 in vivo was also independent of virus replication in a B16 murine melanoma model.70In vitro, mouse melanoma cells were resistant to direct oncolysis and failed to support reovirus replication. Limited reovirus replication was also observed in vivo. However, reovirus was able to induce an antitumor immune response and purged lymph node and splenic metastasis in immunocompetent mice, while it failed to reduce tumor burden in immunodeficient mice. Using human cells in vitro, Prestwich et al. also showed that direct reovirus oncolysis is not required to prime antitumor immunity, with UV-inactivated reovirus being similarly immunogenic, suggesting that only the initial stages of reovirus infection play an essential role in antitumor immunity activation (Figure 2).70
Association between the infections of Trichomonas vaginalis and uterine cervical human papillomavirus: a meta-analysis
Published in Journal of Obstetrics and Gynaecology, 2023
Xuefang Mei, Rui Zhang, Dongxian Li, Xianghuan Xie, Yi Yao, Minghui Gao, Linfei Zhao, Shengyun Zhu, Xiaowei Tian, Zhenke Yang, Shuai Wang, Zhenchao Zhang
Several hypotheses have been postulated, supporting this association. One theory is that parasites can be potential catalysts for the development of secondary infections, including HPV, through the production of a variety of enzymes associated with cytotoxicity and degradation of basement membrane components, such as cysteine proteases (Rodriguez-Cerdeira et al. 2012). In addition, some studies have shown that 82% of TV carry double-stranded RNA viruses, which may be associated with different expressions of enzymes that influence parasite virulence (Wang et al. 1987, Arroyo and Alderete 1995, Rughooputh and Greenwell 2005). Thus, TV also has the potential to alter the transmission of various sexually transmitted diseases, particularly HPV, by increasing virulence.