Search results for "multiplicity of infection"
showing 10 items of 14 documents
Infection of murine hepatocyte cultures by herpes simplex virus (HSV) 1 and 2
1984
A study was undertaken of the interaction between liver cells and Herpes Simplex Virus (HSV) in vitro. Hepatocytes were obtained from HSV-resistant (C57/B16) and from HSV-susceptible (BALB/c, A/J, C3H) mouse strains and cultured according to standard methods. Each culture was infected with several strains of HSV-type 1 or of HSV-type 2, respectively. The multiplicity of infection was 5. The cytopathic effect was evaluated by light- and electron-microscopy. The number of infectious particles was determined using rabbit kidney or Vero cell cultures. All evaluations were made at different time intervals after infection. No difference concerning the replication rate of HSV-1 and 2 in isolated h…
Modeling multipartite virus evolution: the genome formula facilitates rapid adaptation to heterogeneous environments
2020
Multipartite viruses have two or more genome segments, and package different segments into different particle types. Although multipartition is thought to have a cost for virus transmission, its benefits are not clear. Recent experimental work has shown that the equilibrium frequency of viral genome segments, the setpoint genome formula (SGF), can be unbalanced and host-species dependent. These observations have reinvigorated the hypothesis that changes in genome-segment frequencies can lead to changes in virus-gene expression that might be adaptive. Here we explore this hypothesis by developing models of bipartite virus infection, leading to a threefold contribution. First, we show that th…
Why viruses sometimes disperse in groups?
2019
AbstractMany organisms disperse in groups, yet this process is understudied in viruses. Recent work, however, has uncovered different types of collective infectious units, all of which lead to the joint delivery of multiple viral genome copies to target cells, favoring co-infections. Collective spread of viruses can occur through widely different mechanisms, including virion aggregation driven by specific extracellular components, cloaking inside lipid vesicles, encasement in protein matrices, or binding to cell surfaces. Cell-to-cell viral spread, which allows the transmission of individual virions in a confined environment, is yet another mode of clustered virus dissemination. Nevertheles…
Autophagy interferes with human cytomegalovirus genome replication, morphogenesis, and progeny release.
2020
Viral infections are often accompanied by the induction of autophagy as an intrinsic cellular defense mechanism. Herpesviruses have developed strategies to evade autophagic degradation and to manipulate autophagy of the host cells to their benefit. Here we addressed the role of macroautophagy/autophagy in human cytomegalovirus replication and for particle morphogenesis. We found that proteins of the autophagy machinery localize to cytoplasmic viral assembly compartments and enveloped virions in the cytoplasm. Surprisingly, the autophagy receptor SQSTM1/p62 was also found to colocalize with HCMV capsids in the nucleus of infected cells. This finding indicates that the autophagy machinery int…
Lack of evidence of mimivirus replication in human PBMCs
2018
The Acanthamoeba polyphaga mimivirus (APMV) was first isolated during a pneumonia outbreak in Bradford, England, and since its discovery many research groups devoted efforts to understand whether this virus could be associated to human diseases, in particular clinical signs and symptoms of pneumonia. In 2013, we observed cytopathic effect in amoebas (rounding and lysis) inoculated with APMV inoculated PBMCs (peripheral blood mononuclear cell) extracts, and at that point we interpreted those results as mimivirus replication in human PBMCs. Based on these results we decided to further investigate APMV replication in human PBMCs, by transmission electron microscopy (TEM) and qPCR. No viral fac…
Collective Infectious Units in Viruses
2017
Increasing evidence indicates that viruses do not simply propagate as independent virions among cells, organs, and hosts. Instead, viral spread is often mediated by structures that simultaneously transport groups of viral genomes, such as polyploid virions, aggregates of virions, virion-containing proteinaceous structures, secreted lipid vesicles, and virus-induced cell-cell contacts. These structures increase the multiplicity of infection, independently of viral population density and transmission bottlenecks. Collective infectious units may contribute to the maintenance of viral genetic diversity, and could have implications for the evolution of social-like virus-virus interactions. These…
Collective Viral Spread Mediated by Virion Aggregates Promotes the Evolution of Defective Interfering Particles
2020
Recent insights have revealed that viruses use a highly diverse set of strategies to release multiple viral genomes into the same target cells, allowing the emergence of beneficial, but also detrimental, interactions among viruses inside infected cells. This has prompted interest among microbial ecologists and evolutionary biologists in studying how collective dispersal impacts the outcome of viral infections. Here, we have used vesicular stomatitis virus as a model system to study the evolutionary implications of collective dissemination mediated by viral aggregates, since this virus can spontaneously aggregate in the presence of saliva. We find that saliva-driven aggregation has a dual ef…
Collective properties of viral infectivity
2018
Individual virions typically fail to infect cells. Such decoupling between virions and infectious units is most evident in multicomponent and other segmented viruses, but is also frequent in non-segmented viruses. Despite being a well-known observation, the causes and implications of low single-virion infectivity often remain unclear. In principle, this can originate from intrinsic genetic and/or structural virion defects, but also from host infection barriers that limit early viral proliferation. Hence, viruses may have evolved strategies to increase the per-virion likelihood of establishing successful infections. This can be achieved by adopting spread modes that elevate the multiplicity …
Apoptotic-like Leishmania exploit the host´s autophagy machinery to reduce T-cell-mediated parasite elimination
2015
Apoptosis is a well-defined cellular process in which a cell dies, characterized by cell shrinkage and DNA fragmentation. In parasites like Leishmania, the process of apoptosis-like cell death has been described. Moreover upon infection, the apoptotic-like population is essential for disease development, in part by silencing host phagocytes. Nevertheless, the exact mechanism of how apoptosis in unicellular organisms may support infectivity remains unclear. Therefore we investigated the fate of apoptotic-like Leishmania parasites in human host macrophages. Our data showed--in contrast to viable parasites--that apoptotic-like parasites enter an LC3(+), autophagy-like compartment. The compartm…
Optimized production and purification of Coxsackievirus B1 vaccine and its preclinical evaluation in a mouse model.
2017
Coxsackie B viruses are among the most common enteroviruses, causing a wide range of diseases. Recent studies have also suggested that they may contribute to the development of type 1 diabetes. Vaccination would provide an effective way to prevent CVB infections, and the objective of this study was to develop an efficient vaccine production protocol for the generation of novel CVB vaccines. Various steps in the production of a formalin-inactivated Coxsackievirus B1 (CVB1) vaccine were optimized including the Multiplicity Of Infection (MOI) used for virus amplification, virus cultivation time, type of cell growth medium, virus purification method and formulation of the purified virus. Safety…