Introduction to Viruses

Flashcards covering key concepts related to viruses, including their classification, structure, origin hypotheses, infection patterns, and vaccines.

What are viruses classified as?

Acellular, parasitic entities that are not classified within any kingdom.

What is the progressive hypothesis regarding the origin of viruses?

It suggests that viruses originated from RNA and DNA molecules that escaped from a host cell.

What does the regressive hypothesis propose about viral evolution?

It suggests that viruses evolved from free-living cells or from intracellular prokaryotic parasites.

What is the virus-first hypothesis?

It proposes that viruses may have been the first self-replicating entities before the first cells.

What are the main viral structural types discussed?

Helical, Icosahedral, and Complex.

What is an example of a naked icosahedral virus?

Hepatitis A virus or polioviruses.

What are the steps of viral infections in order?

1) Attachment, 2) Entry, 3) Replication, 4) Assembly, 5) Release.

What characterizes an acute viral infection?

Symptoms increase for a short period followed by virus elimination and recovery.

What are asymptomatic infections?

Infections where viruses force cells to produce virions without causing symptoms in the host.

What type of vaccine is created using a killed version of the germ?

Inactivated vaccine.

What is a live attenuated vaccine?

A weakened form of the germ that creates a strong and long-lasting immune response.

What do anti-viral drugs typically do?

They inhibit the virus by blocking the actions of one or more of its proteins.