DNA viruses Flashcards
What type of shape are herpesviruses?
enveloped icosahedral viruses
What are the 9 different Herpesviruses?
alpha family: Herpes Simple virus type 1/2, varicella zoster (VZV)
beta and gamma: Human cytomegalovirus (HCMV), Epstein Barr virus (EBV), Human herpes virus 6/7/8 (HHV-6/7/8) and B virus
What are herpes simplex virus?
first infection can cause herpes gingivostomatitis
following primary infection a latent state persist in trigeminal ganglia (reactivated by trauma, fatigue, sunlight, emotional stress)
HSV can also cause encephalitis
What is Herpes simplex virus type 1?
“Herpes labialis” = cold sore
Herpetic whitlow is HSV infection of fingers and thumbs
Is caused by autoinoculation secondary to genital herpes and health care workers exposed to HSV lesions
What is Herpes simplex virus type 2?
associated with genital herpes
infects epithelial cells of external genitalia, urethra, cervix, rectum and adjacent skin
neonatal herpes can occur
can result in blindness and neurological diseases in babies
What are the phases of HSV transmission, infection, latency and reactivation?
transmission = enters skin or mucous during sexual contact
latency = after primary, virus remains in sacral plexus of spinal cord
virus do not replicate and genes are not expressed
reactivation = can occur without symptoms and host is infectious
What is the Varicella Zoster Virus (VZV)?
2 main syndromes = varicella and zoster
targets receptor = mannose-6-phosphate
VZV is acquired by the respiratory route
dissemination of virus = rash
viruses can remain dormant in dorsal root ganglion (can affect sensory nerve)
reactivation = shingles (usually once only)
What are some anti-herpesvirus agents for HSV and VZV?
oral agents = acyclovir
ophthalmic = trifluridine
topical agents = acyclovir
How does the Human cytomegalovirus infect human cells?
initiated through a non-specific interaction with heparan sulfate proteoglycans
Where does the HCMV persist after infection?
in host and is shed for years in saliva, urine, semen, breastmilk and cervical secretions
What does the HMCV interfere with in the host?
immune functions including antigen presentation, cytokine production and NK cell activity
What groups are the most at risk of HMCV?
organ transplant recipients, immunocompromised individuals and newborn
What does Epstein Barr virus (EBV) cause?
infectious mononucleosis (glandular fever or kissing disease)
How is EBV spread?
oropharyngeal secretions - mouth-to-mouth contact or shared drinking glasses
What does the EBV infect specifically in hosts?
epithelial cells in throat and memory B cells after replication
In Southeast Asia, East and North Africa and Inuit populations what can EBV cause?
nasopharyngeal carcinoma
In tropical Africa what does EBV cause?
Burkitt’s lymphoma
What do the Human papilloma virus (HPV) infect?
epithelial cells through micro-abrasions
What does HPV cause?
genital warts and cancerous lesions
How is HPV spread?
direct contact and autoinoculation via scratching
What does HPV consist of?
> 170 different strains, >40 transmitted sexually
Which HPV is responsible for cervical cancers in women?
HPV16 and 18
What HPV is responsible for genital warts and laryngeal papillomatosis?
HPV 6 and 11
What vaccine targets 9 HPV strains and young adolescents?
Nona-valent human papillomavirus (HPV) vaccine
How is HPV vaccine produced?
L1 coding region of the HPV virus taken
Implanted into a plasmid DNA in yeast
Multiple L1 molecule becomes L1 penton
Multiple L1 penton forms Viral-Like Particle (VLP)
What does the Hepatitis B virus (HBV) infect?
liver cells and causes hepatitis
What is the transmission of HBV?
parenteral transmission
mostly in blood
How is Hepatitis B replicated?
- virus enter cells
- capsid disassembly
- viral relaxed circular DNA enters nucleus of cell
- CCC-DNA created
- transcription to RNA occurs
- RNA packaged in a new capsid
Is HBV infections acute?
yes
What is the term given to HBV individuals who do not have the virus cleared?
chronic carriers
How can HBV be detected?
Hepatitis B surface antigen (HBsAg) is detectable
How do you know if HBV is cleared?
clearance of HBsAg and appearance of anti-HBs
How are vaccines of HBV made?
- virus surface antigen gene isolated
- inserted into yeast
- yeast cells produce HBsAg
- vaccine produced
What does the Polyoma virus JC cause?
fatal demyelinating disease of the CNS –> progressive multifocal leukoencephalopathy (PML) = oligodendrocytes destroyed
