Herpesvirus & Papillomavirus

Question 1

what are some key characteristics of alphaherpesviruses?

Answer 1

• variable host range
• short reproduction cycle
• rapid spread in culture
• efficient destruction of infected cells
• capacity to establish latency in sensory ganglia

Question 2

HSV-1 infects where? HsV-2?

Answer 2

1: above the waist
2: below the waist

Question 3

how is HSV-1 spread?

Answer 3

oral-oral or oral genital

Question 4

how is HSV-2 spread?

Answer 4

primarily genital-genital, oral-genital also possible

Question 5

where do alphaherpesviruses infect?

Answer 5

epithelial cells in the skin or mucosa; mucosa more susceptible

Question 6

what is the incubation period for HSV-1/2?

Answer 6

2-14 days but typically 4-5

Question 7

what are the symptoms of HSV1/2 infection?

Answer 7

flu-like, including localized lesions

only 1/3 show symptoms

lasts for 8 to 12 days

Question 8

describe the latency assoc with HSV1/2

Answer 8

• stationary cells, genome circularizes and stays as an episome in the nucleus
• peripheral ganglia common site of latent infections
• triggered by sunburn, systemic infection, immune impairment, stress

Question 9

what is required for alphaherpesvirus to be overcome?

Answer 9

cell mediated immune response

• people unable to produce antibodies can still handle herpesvirus infections
• T lymphocytes detect antigens presented by MHC class I or II proteins

Question 10

what does herpesvirus do to the immune response?

Answer 10

modulation of immune response

• viral proteins bind antibodies and complement proteins
• counter effects of interferon

Question 11

how are alphaherpeviruses prevented?

Answer 11

avoid contact during active herpes recurrance

Question 12

how are alphaherpesviruses treated?

Answer 12

acyclovir limits virus replication but will no eliminate latent infections

Question 13

what are the key characteristics of betaherpesviruses?

Answer 13

• restricted host range
• long reproductive cycle
• slow progression in cell culture
• enlargement of infected cells (cytomeglia)
• carrier cultures
• latent infection in a variety of tissues
• prototypical member: cytomegalovirus (CMV)

Question 14

what are the key characteristics of gammaherpesviruses?

Answer 14

• restricted host range
• targets T & B lymphocytes
• lytic infections
• latency in lymphoid tissues
• prototypical member: epstein barr virus (EBV)

Question 15

what is Burkett’s lymphoma?

Answer 15

• most common childhood cancer in equatorial Africa
• tumor in jaw, eye socket, ovaries
• in all cases, tumor cells have monoclonal EBV episome
• role of EBV still not understood:
• spur B cell growth, mutations or
• genes transform cells

Question 16

what is Hodgkin’s lymphoma?

Answer 16

• 3 types:
• NL:nodular sclerosing
• MC:mixed cellularity
• LD:lymphocytes depleted

** EBV present in 60-90% of MC & LD tumors, 20-40% of NL tumors

Question 17

what are the immune evasion antiviral host responses for beta/gammaherpesviruses?

Answer 17

• intrinsic
• innate
• adaptive

Question 18

where does CMV persist?

Answer 18

in hematopoietic progenitor cells and macrophages in vitro

Question 19

is there latency with CMV?

Answer 19

no just chronic persistent infection

Question 20

how is CMV controlled?

Answer 20

by healthy, active immune system

Question 21

where does EBV persist?

Answer 21

in memory B cells

virus proteins ensure B cell proliferation and EBV genome replication

Question 22

how are beta/gammaherpesviruses treated and/or prevented?

Answer 22

• infections are usually self limiting in immune competent individuals
• antiviral therapy to inhibit viral genome replication, resistance can develop, and less effective at treating EBV

Question 23

what is the importance of immunoprophylaxis with CMV?

Answer 23

passive transfer of antibodies for prevention of CMV infection, transfer of EBV-specific T lymphocytes

Question 24

are there any vaccines for beta/gammaherpesviruses?

Answer 24

no

Question 25

what kind of virus is human papillmavirus?

Answer 25

• papillomaviridae
• genome: circular dsDNA
• virion: non-enveloped
• proteins:
• L1-cell attachment
• L2-membrane penetration

Question 26

T/F: plantars/palmars warts are human papillomavirus infections

Answer 26

T

Question 27

how does human papillomavirus enter the body and cell?

Answer 27

• gain access thru abrasion of skin
• est. infection in basal layer
• cell pol required for genome replication
• virus production in differentiating cells
• non-lytic, virus released with dead cell shedding

Question 28

how is human papillomavirus infection acquired?

Answer 28

• direct skin-to-skin contact, fomites
• normal skin is very strong barrier
• mucous membranes more susceptible
• virus enters body thru abrasions
• virus is hardy to environ. stresses; allows transmission via fomites

Question 29

what are the symptoms of human papillomavirus infection?

Answer 29

• site of infection
• take months to manifest
• warts- raised or flat-~50% regress on their own in 2 years

Question 30

what is respiratory papillomatosis?

Answer 30

rare complication, respired virus, can be lethal

Question 31

how does oncogenesis - cervical cancer occur in human papillomavirus?

Answer 31

• HPV requires actively replicating cells to replicate and produce progeny
• E7 blocks retinoblastoma (Rb) protein- continued cell proliferation
• E6 blocks the p53 suppressor pathway
• actual path to cancer unknown: viral transformation, cell proliferation leading to cancerous mutation

Question 32

how is human papillomavirus treated and prevented?

Answer 32

• most treatments ablative: liquid nitrogen, surgical excision, laser, caustic chemicals
• no proof that condoms reduce risk
• vaccination: Gardasil