Virus Families

Question 1

Steps in virus life cycle (6)

Answer 1

1. Attachment 2. Entry 3. Uncoating 4. Synthesis of protein and nucleic acid 5. Assembly 6. Release

Question 2

Important structures in a virus

Answer 2

Virion (entire virus particle); envelope; capsid; nucleocapsid; capsomere genome (nucleic acid)

Question 3

Virion structures for Rabies

Answer 3

Nucleoprotein, ribonucleocapsid (RNP) phosphoprotein, polymerase, genomic RNA)

Question 4

Virion structure for HIV

Answer 4

***Nucelocapsid, reverse transcriptase, GP41 (transmembrane glycoprotein), GP120 (docking glycoprotein)

Question 5

Virion structure for HSV1

Answer 5

***Nucleocapsid, DNA, tegument, envelope proteins, lipid envelope

Question 6

Enveloped viruses characterisitics

Answer 6

Envelope derived from host cell membranes, membrane composition can be variable depending on which membranes are used (plasma vs golgi), contains virally encoded proteins that are usually glycoproteins, also can contain host cell proteins, envelope glycoproteins form spike on surface

Question 7

Virion structure

Answer 7

Capsid (coat) protein is the basic unit of structure

Question 8

Functions of capsid proteins

Answer 8

1. Protect viral nucelic acid from environmental stresses 2. Interact specifically with the viral nucleic acid for packaging
2. Interact with host receptors for entry to cell
3. Allow for release of nucleic acid upon entry into new cell
4. Assist in processes of viral and/or host gene regulation

Question 9

Protein coats

Answer 9

1. Icosahedral (spherical, amount of nucleicacid that can be packaged is limited by the size of the particle (closed)
2. Helical: Rod shaped, varying widths and specific architectures; no theoretical limit to the amount of nucleic acid that can be packaged “open” ex. influenza, rabies

Question 10

Viral genome functions

Answer 10

1. Genome replication 2. Genome assembly and packaging 3. Regulation of replication cycle 4. Modulation of host defenses. Not in the genome: genes that encode for protein synthesis machinery, energy metabolism, membrane biosynthesis

Question 11

Enveloped Viruses

Answer 11

Outer enevelope with phospholipids, proteins, glycoproteins, released by budding-some less virulent to cell, sensitive to heat, acids, drying, less likely associated with GI tract disease

Question 12

Non-enveloped (naked) virus

Answer 12

Outer covering is capsid protein, often cell lysis (some more virulent to cell), resistant to heat, acids, drying, survive the GI tract, some replicate in intestines

Question 13

Examples of enveloped viruses

Answer 13

Herpes viruses, orthomyxoviruses (influenza), paramyxoviruses (measles, mumps, respiratory synctial virus)

Question 14

Examples of non-enveloped (naked virus)

Answer 14

Norovirus, rotavirus, adenovirus, paillomavirus, parvovirus

Question 15

Hepatitius A virus

Answer 15

Picornavirus, +ssRNA

Question 16

Hep B virus

Answer 16

Orthohepadnavirus, dsDNA

Question 17

Hep C virus

Answer 17

Hepacivirus, +ssRNA

Question 18

Hep D virus

Answer 18

Deltavirus, -ssRNA, herpes virus, enterovirus

Question 19

5 herpes viruses to know

Answer 19

1. Herpes simplex virus type 1, Herpes simplex virus type 2, 3. Varicella-zoster virus (VZV), 4. Cytomegalovirus (CMV), 5. Epstein-barr virus (EBV)

Question 20

HSV-1/HSV-2 (Herpes virus)

Answer 20

Primary infection: Gingivostomatitis (mouth) or genital herpes), Infection via direct contact, reactivation: “cold sore” or genital herpes, multiple other disease processes (encephalitis, hepatitis, etc.)

Question 21

VZV (Herpes virus)

Answer 21

Primary infection: Chicken pox; reactivtion: Shingles (zoster); varicella much more contagious (1-2 days prior to rash onset until crusted); zoster only by contact, varicella complications: bacterial superinfection; also pneumonitis; hepatitis, encephalitis (ataxia or gneralized), prevention: vaccine

Question 22

CMV (Herpes virus)

Answer 22

Often asymptomatic, can be “infectious mono”, significant disease processes: congenital infections, disease in immune compromised

Question 23

EBV (Herpes virus)

Answer 23

Infectious mononucleosis, complications varied-hepatitis, other, sequelae in the immunocompromised host

Question 24

Influenza A virus

Answer 24

Orthomyxovirus, genome negative sense, single stranded RNA in segments (rotavirus another important GI pathogen with a segmented genome) subtypes named based on envelope hemagglutinin and neuraminidase, important cause of upper respiratory disease and pneumonia

Question 25

Structure of influenza virus

Answer 25

On the outside: Hemagglutinin (HA), Neuraminidase (NA), M2, M1; On the inside: polymerase proteins