Lecture 3 Herpes viruses only Flashcards
What is lecture 3 about?
Herpes and hepatitis in oral health
How many different herpesviruses discussed in lecture what are they?
- Herpes simplex V. type 1 (HSV-1)
- HSV-2
- Varicella zoster virus (VZV)
- Epstein Barr Virus (EBV)
- Cytomegalovirus (CMV)
- Human Herpesvirus 6 (HHV6)
- HHV7
- HHv8/ KSHV
Is herpes species-specific or can be transmitted between species?
Herpes is specific to each species, for example, humans have their own herpes virus,
- Equine Herpesvirus is a problem for horses
- Salmonid are problems for fish farms
Which ones are the neurotropic herpesviruses?
- HSV-1
- HSV-2
- VZV
How do HSV-1 and 2 infect? what do they infect?
HSV1 and 2 only infect proliferating epithelial cells. That’s why having a cut can increase the chances of contracting it since the virus can access the deep proliferating layer of the epidermis.
- It’s neurotropic because it uses an intra axonal transport method to reach an area where it goes through its latency cycle
- Reactivation can occur afterwards due to immunological impairments and that leads to reemergence of the disease
What are the manifestations of HSV-1?
- The majority don’t reactivate, usually goes to a ganglion near oral cavity and stay there and even reemergence is not bad.
- The majority might not even attract attention as they could seem asymptomatic
- The biggest issue with HSV 1 is that it could get to the cornea and leads to Keratitis and that is 2nd only to trauma as a cause of corneal blindness.
- HSV1 can also manifest into hepatic whitlow and that manifests in the thumb
- Used to be a big issue for hygienists and dentists before utilization of gloves.
What is the primary problem with HSV-2?
HSV-2 is a genital infection that has symptoms of growing clusters or sores full of virus practicals that can transfer from one person to another
- One of the biggest manifestations is if the mother is infected and she is having a flare of herpes during birth it can be contracted to the baby and that leads to a systemic neonatal herpes simplex type 2 where the whole body is infested with these sores and virus particles
- The HSV virus would disseminate to different organs and leads:
- Death
- Mental Retardation or neurological disability
- 80% mortality if the antiviral is not used.
What are the rare but fatal manifestation of HSV1 and HSV2?
- HSV 1
- Manifests into herpes simplex encephalitis in adults and young children
- Very rare but very dangerous
- Manifests into herpes simplex encephalitis in adults and young children
- HSV-2
- Manifests into herpes simplex meningitis (Not serious) but usually due to HSV-2 from those with genital infections
What are the common herpes Antivirals? How effective are they?
- Acyclovir
- Valacyclovir
- They’re very effective and they work by halting the DNA replication of the virus of the herpes lytic cycle
Why is acyclovir very effective in stopping the manifestation of the herpes virus?
- Acyclovir is very similar in shape as the nucleoside Deoxyguanosine and it infiltrates the chain they the polymerase is reading it results in the termination of the replication and inhibits the polymerase
- This is so specific that it doesn’t activate with any cell replication but the herpes polymerase which makes it extremely efficient and low risk
- Acyclovir only works with HSV1, 2 and VSV
What is VZV and what are the manifestations? what is the difference between Primary infection and secondary infection?
- ITs the varicella-zoster virus causes chicken pox and shingles.
- Primary infection leads to primary viremia and then the virus replicates in the liver and other organs and leads to secondary viremia
- secondary viremia leads to skin appearance change and vesicular rash.
- The chicken pox has the pox marks on the skin and they’re full of the virus particles so they can transfer via contact and if they dry they can evaporate and contract via inhalation.
- If you get it once you cant get it a second time
What is the problem with VZV latency and reactivation?
- Usually, the Primary infection of chicken pox is very mild and doesn’t cause severe problems
- The reactivation, however, can lead to shingles and that is very problematic because the virus will transit down the peripheral nerve and lead to infecting the dermal areas where it was initiated this leads to Dermatomes
What are the VZV intervention strategies we have now?
- Antivirals
- Acyclovir and Valacyclovir
- Effective vaccines which is an attenuated vaccine
- Varivax is given to children
- Zostavax is given to 60> adults to stop reemergence
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- Zostavax is given to 60> adults to stop reemergence
- Varivax is given to children
What are the lymphotropic herpesviruses?
- They’re viruses that infect cells of the lymphatic system: T cells and B cells, monocytes, macrophages and dendritic cells
- EBV
- CMV
- HHV6
- HHV7
- HHv8
- What are some cancer manifestation of EBV?