what is the structure of a virus (4)
- genome
- capsid
- envelope
- glycoprotein spike
what causes latency
a lack of a specific host cell protein needed to activate viral genes and turn on viral replication
what are the stages of viral infection
- prodomal or incubation
- latency
- activation of viral replication
how do viruses cause damage (5)
- hypersensitivity reaction (Type II and Type IV)
- components toxic to the cell
- transform a benigh cell to a malignant cell
- alter immune response (humoral and cellular)
- cause cytoplasmic and/or nuclear changes
how are virses classified (6)
- morphology
- physiochemical properties
- genome (RNA/ DNA)
- macromolecules
- antigenic properties
- biological properties
how many types of papillomavirus - HPV
more than 150
more than 30 are sexually transmitted
what types of cancer are caused by HPV (6)
- anal cancer - 91%
- cervical cancer - 91%
- vaginal cancer - 75%
- oropharyngeal - 72%
- vulvar cancer - 69%
- penile cancer - 63%
types of warts (4)
- common warts
- foot warts/ verrucae
- flat warts
- periungual warts
herpes simplex has 2 types; what are they and what do they cause
- HSV-1: cold sores
- HSV -2: sexually transmitted
which virus causes chicken pox and shingles
varecella zoster virus
what does epstein-barr virus cause
mononucleosis 35-50% of time i.e., glandular fever
what are the symptoms of glandular fever
- fatigue, loss of appetite, headache
- photophobia
- sore throat
- lymphatic swelling
- cough
- enlarged spleen
- chills, fever, aches
other herpes virus include:
- cytomegalovirus (HHV-5)
- hairy leukopakia (EBV HHV-4)
- kaposi’s sarcoma (HHV-*)
pox virus include
- smallpox (now irradicated)
- molluscum contagiosum
what is a retrovirus
it inserts a copy of it RNA genome into the DNA of a host cell, thus changing the genome of that cell
what enzyme does HIV use to replicate itself
reverse transcriptase
it destroys CD4 cells by damaging cell membranes
what is the incubation period for HIV
1-10 years
causes a profound defect in cell-mediated immunity
what virus is very very tiny, spread by the faeco-oral route
picornaviruses e.g., polio, hepatitis A
polio can occur in various severities:
- sub-clinical - none or very mild symptoms
- non-paralytic
- paralytic
how is hepatitis B virus communicable
by contact with infected body fluids
how do prions cause damage to cells
prions on the cell surface allow too much fluid to enter the cell, producing a spongry appearance when cross-sections of brain tissue are examined under a microscope
