4. Periodontal Disease, Viral Infection & Cancer

Question 1

What are dental caries?

Answer 1

Localized destruction of the hard tissues of the tooth (i.e. death/decay of the tissue caused by certain microbes

Question 2

What type of bacteria causes supragingival plaque and subgingival plaque? Where are each types of plaque located on the teeth?

Answer 2

Supragingival Plaque: on the tops of the teeth
-Caused by gram (+) bacteria

Subgingival Plaque: on the bottom (near the roots) of teeth
-Caused by gram (-) bacteria

Question 3

Describe the progression of periodontal disease starting w/ healthy gums.

Answer 3

1. Healthy Gums
2. Gingivitis-inflammation of the gums
3. Periodontitis-decay of gums and teeth

Question 4

What are virulence factors?

Answer 4

Molecules expressed/secreted by pathogens that allow them to do things that infect the host

Question 5

Name 5 virulence factors of the pathogens associated w/ periodontal disease.

Answer 5

1. Lipopolysaccharide (LPS)
2. Protease
3. Toxin
4. Fimbriae
5. Short Chain Fatty Acids

Question 6

What pathogen is responsible for Kaposi’s sarcoma (KS?

Answer 6

Kaposi’s sarcoma-associated herpes virus (KSHV)

Question 7

Name 4 general characteristics of the viral structure.

Answer 7

1. ds DNA
2. Icosahedral capsid
3. Tegument (layer b/w envelope and nucleocapsid that aids in viral replication and evasion of host immune response)

Question 8

Name 3 Histological features of KS.

Answer 8

1, endothelial marker, KSHV+

2. Highly angiogenic (creates new blood vessels)
3. Infiltration of inflammatory cells

Question 9

Describe how KSHV gets into the host and what it does once inside.

Answer 9

1. Primary infection: KSHV in saliva enters individuals mouth
2. Secondary Infection: Latency-virus’s circular genome is inserted into host cells
3. Reactivation of KSHV
4. Lytic replication of KSHV
5. New KSHV can now infect other hosts (transmission)

Question 10

How is the KSHV genome epigenetically silenced during latency?

Answer 10

Via histone deacetylation/repressive tri-methylation within the latency locus.

Question 11

Where do about 20% of patients develope KS lesions first?

Answer 11

In the oral cavity

Question 12

Why are AIDS/HIV patients more prone to getting periodontal disease?

Answer 12

These patients have a suppressed immune system and reduced CD4+ T-cell counts

Question 13

What is the name of the more severe type of periodontal disease that AIDS/HIV patients get?

Answer 13

Necrotizing ulcerative periodontitis (NUP)

Question 14

Which pathogens are the primary cause of periodontal disease?

Answer 14

Anaerobic Gram (-) bacteria – cause chronic inflammation and produce multiple metabolic by-products (i.e. virulence factors)

Question 15

Which virulence factor does the saliva of patients with severe periodontal disease have significantly higher levels of? Why is this significant?

Answer 15

Short chain fatty acids (SCFA)

Significance: SCFA strongly induces lytic gene expression in KSHV latently infected cells

Question 16

Do all SCFAs induce KSHV lytic replication in the same way?

Answer 16

Yes, but they have different dose-dependent and synergistic manners

Question 17

How do SCFAs induce/activate lytic gene expression?

Answer 17

Increase histone acetylation while decreasing repressive tri-methylation in the promoter of KSHV lytic gene, RTA

Question 18

What other effect does SCFAs have? and why?

Answer 18

Increases KSHV infection of oral epithelial cells

How: SCFAs inhibit induction of type-1 inteferon during viral infection to render cells more susceptible to infection