Lecture #23 Viruses

Question 1

Replication

Answer 1

Dependent on a host organism

Question 2

Bacteriophage

Answer 2

Insert genetic material directly into host cell

Double-stranded genome

Question 3

Two types of cycles

Answer 3

Lytic cycle (phage T4)

Lysogenic cycle (Phage Lambda)

Question 4

5 Basic Steps of REPLICATION

Answer 4

Attachment

Entry

Synthesis

Assembly

Release

Question 5

Production of new viruses requires:

Answer 5

Replication of the genome

Synthesis of viral proteins

Question 6

Membrane Fusion

Answer 6

Capsid is uncoated

Question 7

Most DNA viruses assemble in the:

Answer 7

Nucleus

Question 8

Most RNA viruses assemble in the:

Answer 8

Cytoplasm

Question 9

Number of viruses produced and released depends on…

Answer 9

Type of virus
Size of virus
Initial health of host cell

Question 10

Release of naked virus…

Answer 10

Death of host cell

Question 11

Budding of enveloped viruses…

Answer 11

Host cell usually survives

Question 12

Herpesviridae (family)

Answer 12

Enveloped, polyhedral capsids, double stranded DNA

The most prevalent DNA viruses

Often LATENT

Question 13

HHV-1

Answer 13

Infections typically occur via casual contact in children

Question 14

HHV-2

Answer 14

Infections are typically acquired between the ages of 15 and 29 from sexual activity

Question 15

Transmission of the herpes virus

Answer 15

Occurs through bodily contact
Usually via active lesions

Viruses enter the body through cracks or cuts in mucus membranes

Question 16

SYNCYTIA

Answer 16

Cells with the virus fuse with adjacent uninflected cells and spread the virus from cell to cell

Question 17

Diagnosis of herpes virus

Answer 17

Lesions in the genital region and on the lips are diagnostic

Question 18

Treatment of herpes virus

Answer 18

Can be CONTROLLED with chemotherapeutic agents

Topical applications of the drugs limit the duration of lesions and reduce viral shedding

NO CURE!

Question 19

VARICELLA-ZOSTER VIRUS

Answer 19

Also known as HHV-3 or VZV

Causes two diseases
Varicella (chicken pox)
Herpes Zooster (shingles)

Question 20

Chickenpox

Answer 20

Viruses enter through the skin, respiratory tract, or eyes

Viruses replicate at the site of infection then travel via the blood throughout the body

Characteristic skin lesions appear 2-3 weeks after infection

The disease is usually mild

Chickenpox in adults is typically more severe

Question 21

Shingles

Answer 21

Latent virus can reactivate, producing a rash known as shingles

The rash is localized along a DERMATOME (band of skin)

Question 22

Diagnosis of chickenpox

Answer 22

Diagnosed from the characteristic lesions

Shingle lesions localized along a DERMATOME are characteristic

Question 23

Treatment of chickenpox

Answer 23

Chickenpox is usually self-limiting

Shingles treatment involves management of symptoms and bed rest

Shingles vaccine is about 50% effective

Question 24

Papillomaviridae

Answer 24

Double-stranded DNA

Naked (no envelope), icosahedral capsid

PAPILLOMAS: benign growths (warts) on the epithelial of the skin or mucus membranes

Question 25

Transmission of warts

Answer 25

Direct contact and fomites Stable outside of the body Almost all cases of cervical cancer are caused by (HPV)

Question 26

Diagnosis of Papillomaviridae

Answer 26

Observation of the papilloma Genetic probes can determine specific strains Pap smears

Question 27

Treatment of Papillomaviridae

Answer 27

Warts usually regress over time Surgical, chemical, laser, cryo-remover Standard cancer treatments for cervical cancer

Question 28

Virus

Answer 28

ACELLULAR infectious agent Possesses one or more pieces of nucleic acid Protein coat called CAPSID Some viruses have a membrane-like structure called an ENVELOPE