Papilloma Flashcards
What is a koilocyte (Welle, Maulidn, JPC)
swollen keratinocytes with eosinophilic to lightly basophilic cytoplasm and perinuclear halo
-can have multiple nuceli
Name viral cytopathic effects papilloma (JPC)
- Koilocytes
- Intranuclear inclusion bodies
- Large, irregular keratohyalin granules (in exophytic types)
- Variable degress of ortho/para HK
- Degenerating KC with eosinophilic cytoplasmic inclusions (represent aggregates of keratin)- may be confused with POX!
How are papillomaviruses sperad
- Transplacental (FcPV-a in almost all cats from early in life)
- Fomites (direct and indirect contact)
- Skin abrasions
- bovine- arthropod, vertical, blood
- horse-flies, miking machines + co factors: malnutrition, hormonal imbalance, mutations, long term exposure to sunlight
Name 3 genera
- Lambda
- Tau
- Chi
What are the predispositions /predilections
- IgA deficiency- oral papillomatosis
- GC, chemotherapy
Predilection in old animals (accumulations of spontaneous mutations throughout life)
Which proteins are involved in malignant transformation
- p53
- p16
How does the infection occur
- Microtrauma allows PV to intreact with BM
- PV enters cells after binding to alpha 6 integrin - infects KRT in SB
- Basal cell replication- episomal DNA spread through basal cell population and maintain infection, during this phase normal epithelial regulation not altered, infection is asymptomatic, non-infective
- PV to complete the life cycle - in a basal cell that undergoes terminal differentiation
- Replication of PV DNA dependent on host nucelus
-key feature: ability to prevent cells from leaving the S phase (where DNA replicate , ensure that KC keep dividing, amplifies infection because every divided KC will be infected - genome replication in SS and SG
- release new infection in keratinized squames - achantosis, HK, koilocytes in SS, giant KH granules in SG
PV- induced cancer. What is the critical step
integration od E6 and E7 genes (proteins- oncogenes) in host DNA
Where are early genes expressed
in basal and suprabasal layers
Where are late genes expressed
in SS and SG
Where are virions expressed
-upper SG and SC
How are infective viruses spread
-released due to normal cell death
What are the methods of evading immune system (ch infections)
- infection of immune privileged site (epidermis, HF)
- no idnuction of type I IFN of infected KC by CPV-2
Name 3 components of genes
- Early genes (E7)
- Late genes (L2)
- LCR - long control region
What are the oncogens
E5,E6,E7
What is the function of E1, E2
-regulation of viral DNA replication
Function of E3
modulates immune response of infected cells
Function of E4
disrupt cytokeratins facilitating viral release (viral replication)
Function of E5
BPV-1, BPV-2
-inhibits intercellular communication through gap junctions
-activates PDGF receptor
-down regulates MCH-1
-interactions with growth factors
functions of E6 and E7
= cell proliferation and immortalization
E6-disrupts focal adhesions, degrade p53 (accumulate various mutations)
E7-cell growth, chromosomal instability, , inhibit retinoblastoma (Rb): important tumor suppressor protein
What is function of late genes
=coded in SS and SG
L1, L2- genes encode for viral capid protein
L1- major capsid protein highly immunogenic, used to classify PV in genera
What are LCR (long control region)
-does not code proteins
-regulates viral gene transcription (when and which genes are necessary in the process of infections)