Microbiology Trans - Intro to Virology

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Questions and Answers

What type of genetic material does a Type VI retrovirus contain?

Single-stranded RNA (correct)

Double-stranded DNA

Double-stranded RNA

Single-stranded DNA

What is the family name of the virus that causes Hepatitis B?

Retroviridae

Picornaviridae

Hepadnaviridae (correct)

Orthomyxoviridae

Which of the following viruses replicates in the nucleus?

Hepatitis B (correct)

Influenza

Adinovirus

HIV

What does the attachment phase of viral replication involve?

Interaction with receptors on host cells Signup and view all the answers

Which viruses are noted for having a capsid or phospholipid envelope that interacts with host cell receptors?

SARS and HIV Signup and view all the answers

In which cellular location do RNA viruses typically replicate?

Cytoplasm Signup and view all the answers

What is the function of inserted viral proteins (peplomers)?

They help in attachment and immunity induction. Signup and view all the answers

Which type of virus can withstand gastric acidity?

Icosahedral naked virus Signup and view all the answers

What shape does a helical virus take?

Helical or spiral Signup and view all the answers

What type of symmetry does an icosahedral virus have?

Polyhedral with 20 flat sides Signup and view all the answers

Which mode of transmission does the Poliovirus utilize?

Feco-oral route Signup and view all the answers

What is the main component of a capsid?

Protein coat Signup and view all the answers

Which type of virus is exemplified by Rabies?

Complex virus Signup and view all the answers

What type of virus often has a lipid envelope?

Icosahedral enveloped virus Signup and view all the answers

Which viral structure does NOT usually have distinct symmetry features?

Complex virus Signup and view all the answers

What is a characteristic of viruses when they are outside of living cells?

They are unable to self-replicate. Signup and view all the answers

Which of the following groups of organisms are similar to viruses?

Rickettsia, Mycoplasma, and Chlamydia Signup and view all the answers

What role do interferons play in the immune response to viruses?

They signal neighboring cells to produce antiviral proteins. Signup and view all the answers

What happens to viruses when interferons are present?

Their ability to multiply is inhibited. Signup and view all the answers

Which of the following is NOT true about viruses?

Viruses can be replicated outside a host. Signup and view all the answers

What is the function of the IFN gene in relation to viruses?

To activate interferons. Signup and view all the answers

Which taxonomic order do Herpesvirales belong to?

Herpesvirales Signup and view all the answers

Which of the following species is a Betacoronavirus?

SARS CoV2 Signup and view all the answers

Why are viruses resistant to antibiotics?

They do not have a cellular structure. Signup and view all the answers

What action do interferons take when released outside a cell?

They signal neighboring host cells to produce antiviral proteins. Signup and view all the answers

What phenomenon describes the ability of infected cells to stick to red blood cells?

Hemadsorption Signup and view all the answers

Which type of viruses are associated with chronic infections and the formation of tumors?

Oncogenic viruses Signup and view all the answers

What is indicated by the term 'ballooning of cells' in viral infections?

Cells become round and enlarged Signup and view all the answers

Which viruses are known to cause syncytium formation?

Respiratory Syncytial Virus (RSV) and Measles Signup and view all the answers

What is the result of a successful hemagglutination test?

Agglutination of red blood cells Signup and view all the answers

During chronic infections caused by certain viruses, which of the following occurs?

Low level of viral production without immune clearance Signup and view all the answers

What characterizes the cellular morphology in infections like those caused by Enterovirus 71?

Cells lose their original shape and become ballooned Signup and view all the answers

What is the common mechanism for oncogenic viruses to lead to tumors in hosts?

Cellular growth leading to tumors Signup and view all the answers

What is the typical outcome of hemadsorption in infected cells?

Adherence to erythrocytes Signup and view all the answers

Which of the following viruses is least likely to cause ballooning of cells?

Mumps virus Signup and view all the answers

Which glycoprotein of HIV is known for its role in receptor attachment?

gp120 Signup and view all the answers

What receptor does the glycoprotein gp120 of HIV bind to on host cells?

CD4+ Signup and view all the answers

What is the significance of glycoprotein spikes for viruses?

They must interact with host cell receptors for viral entry. Signup and view all the answers

What does a decrease in CD4+ cells indicate in HIV patients?

Higher susceptibility to opportunistic infections. Signup and view all the answers

Which virus is associated with Kaposi’s Sarcoma?

Herpesvirus 8 Signup and view all the answers

What is the role of the influenza hemagglutinin glycoprotein?

Promotes viral attachment to host cells. Signup and view all the answers

Which antigen is used to detect antibodies in Hepatitis B patients?

HBsAg Signup and view all the answers

What type of virus is Hepatitis B classified as?

dsDNA virus Signup and view all the answers

Which receptor is primarily involved in the entry of the Kaposi’s Sarcoma-associated Herpes Virus?

CD98 Signup and view all the answers

What is viral tropism?

The ability of a virus to infect specific host tissues. Signup and view all the answers

Study Notes

Capsid Structure and Function

The capsid is a protein coat that encloses a virus's genetic material.
Three types of symmetry are observed in capsids:
- Icosahedral: Polyhedral with 20 flat sides; can be naked or enveloped.
- Helical: Spiral or cylindrical in shape; can be naked or enveloped.
- Complex: Lacks standard symmetry; examples include Poxvirus and Rabies virus.

Viral Resistance and Stability

Viruses can be destroyed by heat or detergents.
Different viruses exhibit varying sensitivity to gastric acidity and environmental factors.

Mode of Transmission

Direct contact: Example includes HIV transmission.
Feco-oral route: Example includes Poliovirus.

Viral Proteins and Host Interaction

Inserted viral proteins (peplomers) facilitate:
- Attachment to host cell receptors (e.g., gp120 in HIV binds to CD4+).
- Induction of protective immunity (hemagglutinin for influenza vaccine).

Viral Serotyping and Antigenic Variants

Viruses like Hepatitis B exhibit different surface antigens:
- HBsAg: Hepatitis B surface Antigen.
- HBcAg: Hepatitis B core Antigen.
- HBeAg: Hepatitis B e Antigen.
Antigens allow for identification of antibodies produced by patients.

Oncogenic Viruses and Infection Dynamics

Oncogenic viruses can cause chronic infections with low levels of viral production (e.g., Hepatitis B and C).
Hemadsorption allows cells to adhere to mammalian red blood cells, displaying specific receptor patterns.

Cell Infection Dynamics

Syncytium formation: Infected cells can fuse with neighboring cells, forming multi-nucleated giant cells.
Ballooning of cells: Viral infection can alter cell shape, causing infected cells to become rounded.

Virus Classification and Taxonomy

Taxonomy is structured hierarchically (Order, Family, Subfamily, Genus, Species).
Examples of notable families and viruses include:
- Retroviridae: HIV involves ssRNA (+).
- Hepadnaviridae: Hepatitis B involves dsDNA (+/-).

Viral Replication Process

Attachment/Absorption: Viral proteins interact with specific host cell receptors determining tropism.
Penetration and Synthesis: RNA viruses replicate primarily in the cytoplasm, while most DNA viruses replicate in the nucleus (excluding certain families like poxviruses).

Interferon and Immune Response

Interferons are proteins that inhibit viral replication by signaling neighboring cells to produce antiviral proteins, enhancing natural defenses against viral infections.

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Description

This quiz explores the structure of viruses, focusing on the protein coat, modes of transmission, and environmental factors affecting them. It covers essential topics like capsids, symmetry, and specific transmission routes such as direct contact and the fecal-oral route.