Virology Basics: Introduction to Viruses

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What is the main function of the viral genome in directing the synthesis of viral components?

Replication of the viral genome

Formation of infectious progeny virions (correct)

Synthesis of cellular components

Cellular energy generation

What distinguishes viroids from viruses based on the provided text?

Viroids have a DNA genome

Viroids contain a biosynthetic system

Viroids lack a protein coat (correct)

Viroids infect bacteria

What is a prion?

DNA segment

Single-celled organism

Single protein molecule (correct)

RNA molecule

Which ancient text mentions evidence of several viral diseases?

The Iliad by Homer Signup and view all the answers

What initiates the next infectious cycle in viruses?

Progeny virion disassembly Signup and view all the answers

How long have viruses been known as distinct biological entities?

Less than 100 years Signup and view all the answers

What did Beijerinck term the submicroscopic agent responsible for tobacco mosaic disease?

Contagium vivum fluidum Signup and view all the answers

Who identified viruses that cause leukemias or solid tumors in chickens in 1908 and 1911, respectively?

Vilhelm Ellerman and Olaf Bang Signup and view all the answers

Who first recognized that bacteria could be hosts to viruses?

Friedrick Twort Signup and view all the answers

What is the function of capsid in a virus?

Encloses the nucleic acid genome Signup and view all the answers

When was the term 'virus' eventually simplified from contagium vivum fluidum?

1898 Signup and view all the answers

What did Loeffler and Frosch deduce about infectious filterable agents in 1898?

Comprised small particles Signup and view all the answers

What was the practice called where healthy individuals were inoculated with material from smallpox pustules?

Variolation Signup and view all the answers

What did variolation involve?

Inoculating healthy individuals with smallpox material Signup and view all the answers

Who recognized the principle on which modern methods of viral immunization are based?

Edward Jenner Signup and view all the answers

What observation led Edward Jenner to his great insight regarding smallpox protection?

Milkmaids contracted cowpox Signup and view all the answers

What were the consequences of variolation according to the text?

Serious skin lesions at the site of inoculation and rash Signup and view all the answers

What event occurred in the 11th century in China and India related to smallpox?

Widespread practice of variolation Signup and view all the answers

What is a key difference between the nucleocapsids of viruses with helical symmetry and icosahedral structures?

Regular, periodic interaction between capsid protein and nucleic acid Signup and view all the answers

Which type of genome is typically found in animal viruses with helical symmetry?

RNA genomes Signup and view all the answers

What is a function of the structural proteins in viruses?

Facilitate transfer of viral nucleic acid Signup and view all the answers

Which statement about the structure of paxoviruses is true?

Brick-shaped with ridges on the external surface Signup and view all the answers

What determines the antigenic characteristics of a virus?

Structural proteins Signup and view all the answers

Why is it not possible for 'empty' helical particles to form?

Regular, periodic interaction between capsid protein and nucleic acid Signup and view all the answers

What is recommended if rubella is diagnosed in the first trimester of pregnancy?

Immediate pregnancy termination Signup and view all the answers

Why is accurate laboratory identification of the infecting virus necessary for the use of antiviral agents?

To ensure effectiveness of the antiviral agent Signup and view all the answers

In chronic diseases like HIV and hepatitis B virus, what is required to make decisions about therapy initiation?

Full understanding of laboratory findings Signup and view all the answers

How are drug combinations for patients with viral infections typically selected?

According to the drug resistance profile of the infecting virus strain Signup and view all the answers

What is the purpose of virus load testing in monitoring response to therapy?

To monitor the response and adjust therapy as needed Signup and view all the answers

Why might blood banks screen for viruses like HIV and hepatitis B and C?

To prevent spread through blood transfusions Signup and view all the answers