Biology » Viruses » Virus Infections and Hosts

Summarizing Virus Infections and Hosts


Viral replication within a living cell always produces changes in the cell, sometimes resulting in cell death and sometimes slowly killing the infected cells. There are six basic stages in the virus replication cycle: attachment, penetration, uncoating, replication, assembly, and release. A viral infection may be productive, resulting in new virions, or nonproductive, which means that the virus remains inside the cell without producing new virions.

Bacteriophages are viruses that infect bacteria. They have two different modes of replication: the lytic cycle, where the virus replicates and bursts out of the bacteria, and the lysogenic cycle, which involves the incorporation of the viral genome into the bacterial host genome. Animal viruses cause a variety of infections, with some causing chronic symptoms (hepatitis C), some intermittent symptoms (latent viruses such a herpes simplex virus 1), and others that cause very few symptoms, if any (human herpesviruses 6 and 7). Oncogenic viruses in animals have the ability to cause cancer by interfering with the regulation of the host cell cycle. Viruses of plants are responsible for significant economic damage in both agriculture and plants used for ornamentation.


acute disease

disease where the symptoms rise and fall within a short period of time

asymptomatic disease

disease where there are no symptoms and the individual is unaware of being infected unless lab tests are performed


anti-HIV drug that inhibits the viral enzyme reverse transcriptase


virus that infects bacteria


method of exit from the cell used in certain animal viruses, where virions leave the cell individually by capturing a piece of the host plasma membrane

cell necrosis

cell death

chronic infection

describes when the virus persists in the body for a long period of time


causing cell damage


method of entry by some enveloped viruses, where the viral envelope fuses with the plasma membrane of the host cell


appearance of a plant tumor

horizontal transmission

transmission of a disease between unrelated individuals


abnormally high cell growth and division


abnormally low cell growth and division

intermittent symptom

symptom that occurs periodically


virus that remains in the body for a long period of time but only causes intermittent symptoms


bursting of a cell

lytic cycle

type of virus replication in which virions are released through lysis, or bursting, of the cell

lysogenic cycle

type of virus replication in which the viral genome is incorporated into the genome of the host cell

oncogenic virus

virus that has the ability to cause cancer


cell type that is able to support productive replication of a virus


viral infection that leads to the production of new virions


phage DNA that is incorporated into the host cell genome

vertical transmission

transmission of disease from parent to offspring

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