One example is the leaky cell membrane that appears after infection with picornaviruses or Sindbis virus; the change in intracellular ion concentrations that results from the leaky membrane may favor translation of the more salt-stable e.
In poliovirus or herpes simplex infections, for example, selective inhibition of host protein synthesis occurs prior to Cytopathic effect essay maximal synthesis of viral proteins. Inclusion bodies vary with viral strain.
To observe this process, cells are seeded on a glass surface and a confluent monolayer of host cell is formed. The spread of infection is limited by host factors such as humoral and cell-mediated immune responses, interferons and other nonspecific inhibitors. Examples include the association of early virus gene products e.
Cell DNA synthesis is inhibited in most cytolytic virus infections. Inoculations always occur at low multiplicity of infection because at high multiplicity of infection, all CPEs occur rapidly.
Once enlarged, the cells clump together in clusters. Reoviruses and some herpesviruses may be exceptions in that they cause a decrease in cell DNA synthesis before a substantial decline in cellular protein synthesis occurs.
Relation of Cellular Effects to Viral Pathogenesis Although most of the events that damage or modify the host cell during lytic infection are difficult to separate from viral replication, the effects are not always linked directly to the production of progeny virions.
Transforming Infections The term oncogenic transformation refers to the process through which control of cell proliferation is genetically modified, so that the cell becomes cancerous see Ch.
Although large cell fusions are sometimes visible without staining, this type of CPE is typically detected after host cell fixation and staining. Eventually, the host cells detach from the surface. Rubella virus infections are associated with demyelination without neural degeneration.
Biologic Effects The biologic consequences of virus infection results from the aforementioned biochemical, physiological, structural, morphological and genetic changes. Many CPEs can be seen in unfixed, unstained cells under the low power of an optical microscopewith the condenser down and the iris diaphragm partly closed.
This different mode of transfer differentiates it from total and subtotal destruction and causes the characteristic localized effects. When the cell survives, the virus genome may persist within the cell, possibly leading to continued instability of cellular genomic material or to altered expression of cellular genes e.
For example, in influenza virus and herpes simplex virus infections, cellular mRNA stops binding with ribosomes to form polyribosomes; only virus-specific mRNA is bound, giving viral mRNAs a selective advantage.
They may be single or multiple, small or large, and round or irregularly shaped. Focal degeneration is due to direct cell-to-cell transfer of the virus rather than diffusion through the extracellular medium.Virus Titration Essay.
When detecting the virus, the cytopathic effect is looked at, whether there is lysis of the cells, vacuolation, formation of syncytia and the presence of inclusion bodies. TCID50, is the measure of the infectious titre. Read this essay on Virus. Come browse our large digital warehouse of free sample essays.
Get the knowledge you need in order to pass your classes and more. Only at billsimas.com". Cytopathic effect or cytopathogenic effect (abbreviated CPE) refers to structural changes in host cells that are caused by viral invasion. The infecting virus causes lysis of the host cell or when the cell dies without lysis due to an inability to reproduce.
Both of these effects occur due to CPEs. An alternative system has been developed using the microtitre well tray format!'2 that automatically performs replicate assays, reads cytopathic effect and calculates the titre.
The findings employing the system for titrating measles, rubella and mumps viruses are reported here.
A particularly striking cytopathic effect of some viral infections is the formation of syncytia, or polykaryocytes, which are large cytoplasmic masses that contain many nuclei (poly, many; karyon, nucleus) and are usually produced by fusion of infected cells.
The mechanism of cell fusion during viral infection probably results from the interaction between viral gene products and host cell membranes. When detecting the virus, the cytopathic effect is looked at, whether there is lysis of the cells, vacuolation, formation of syncytia and the presence of inclusion Read More Words: - Pages: 4.Download