China
Africa
Explore chapters and articles related to this topic
Recombinant DNA Technology and Gene Therapy Using Viruses
Published in Patricia G. Melloy, Viruses and Society, 2023
Many organisms have relationships with viruses. One of the best-understood examples of a mutualistic type of relationship is between the parasitoid wasp and a polydnavirus. The virus depends on the wasp for replication, and the virus expresses genes that allow wasp eggs laid in an insect larva to survive (Roossinck 2011). As mentioned briefly in Chapter 1, humans carry the remnants of retroviruses in their genome, and some of these integrated genes were thought to have a positive effect on evolution. For example, the syncytin genes, derived from ancient retroviruses that integrated into the genome, are expressed in a specialized cell type of the human placenta. Expression of these genes allows for cell fusion events that are critical to the structure of the placenta (Roossinck 2011; Roberts et al. 2021). Other scientists are studying what is known as the human virome, the portion of the human microbiome made up of viruses—all the viruses that inhabit the cells of the body. Although some viruses in our virome infect our cells, even without us knowing it, in most cases, most of the viruses in our virome are infecting the bacteria that inhabit our bodies. These viruses are known as bacteriophages or phages. More research still needs to be done as to how the kind and number of viruses in our virome affect our general health (Pride 2020; Liang and Bushman 2021). Given that viruses do many things and are all around us, some say that life on the planet would not work without viruses (Nuwer 2020). Now that we have recognized the importance of viruses, how are scientists exploiting the characteristics of viruses for our own medicinal purposes?
Predictive tools to determine risk of infection in kidney transplant recipients
Published in Expert Review of Anti-infective Therapy, 2020
Mario Fernández-Ruiz, Francisco López-Medrano, José María Aguado
The use of viral replication kinetics as a surrogate for immunosuppression is founded on a simple hypothesis. Human virome is composed of a staggering diversity of single- and double-stranded RNA and DNA viruses that infect the human being at multiple anatomical sites. These viral communities establish a complex, bidirectional interplay with components of host immunity that goes beyond the traditional paradigm of host-pathogen interaction [95]. Replication of commensal and opportunistic viruses exert a detrimental impact on the immune function leading to allograft rejection or predisposing to opportunistic infections, whereas no pathogenic effect has been demonstrated for the so-called ‘orphan viruses’. Moreover, some viruses may even have a beneficial immunomodulatory role [96]. The expansion of human virome is tightly controlled by the innate and, to a greater extent, adaptive arms of immune system. Plasma or blood loads of highly prevalent viruses reflect a dynamic steady state between virus replication and host’s response in non-immunocompromised individuals, often based on a high daily turnover rate. Immunosuppressive therapy may alter this balance, resulting in increasing or persistent replication, as also observed for other immunocompromised hosts. The net state of immunosuppression would be inferred from viral kinetics, with high and low viral loads suggesting an increased risk of post-transplant infection and graft rejection, respectively.
The triad: respiratory microbiome – virus – immune response in the pathophysiology of pulmonary viral infections
Published in Expert Review of Respiratory Medicine, 2021
Bárbara N. Porto, Theo J. Moraes
The respiratory virome is an integral part of the human microbiome and studies aiming at characterizing the composition of the respiratory virome have contributed to a better understanding of the role it plays during acute respiratory infections. The human virome is composed by eukaryotic viruses (viruses infecting eukaryotic cells), bacteriophages (viruses that infect human-hosted bacteria), archaeal viruses (viruses that infect archaea) and virus-derived elements integrated to host chromosomes that are able to change host gene expression and even give rise to infectious virus, such as prophages or endogenous retroviruses [154,155]. As with the mucosal bacterial inhabitants, the respiratory virome is categorized as commensals or opportunistic pathogens. The balance between being a commensal or becoming a pathogen is determined by several direct and indirect factors of the viral community itself or the host, such as genetic factors and the immune response [156]. Previous studies demonstrate that the lung virome plays a crucial role in modulating and priming the host immunity. The presence of multiple transitory viruses in asymptomatic individuals maintains a low-level immune response by activating several pattern-recognition receptors and ultimately leading to an antiviral immunity, which may confer an advantage to the host [154,157]; this paradigm has been coined the ‘old friends’ hypothesis [158]. However, an increased respiratory viral load has been shown to cause exacerbations of chronic pulmonary diseases, including COPD, cystic fibrosis, and asthma [159,160], which may contribute to the pathogenesis of such conditions.
Bugs in the system: bringing the human microbiome to bear in cancer immunotherapy
Published in Gut Microbes, 2019
Christopher Strouse, Ashutosh Mangalam, Jun Zhang
Finally, because 16S rRNA sequencing has been the primary tool for characterization of the microbiome, the presence of other microorganisms, such as viruses and fungi, have not been well captured or characterized. Understanding of the human virome, the collection of all viruses in a human, is in its nascency compared to our understanding of the bacterial microbiome, though it may have a significant effect on cytotoxic T-cell immunity.17 It is not known whether changes and diversity within these populations affect the host immune system, and whether they are adequately reflected in the analyses of the colonic bacterial microbial community.