Week 3 - Viruses, Infection and Cancer Flashcards
What are the 3 chronic infectious causes of Cancer?
Viruses, Bacteria and Trematodes
Name 8 viruses that cause cancer.
EBV HBV HCV HHV-8 HIV-1 HPV HTLV-1 MC Polyoma Virus
What cancer does EBV cause, what type of cells does it affect and describe its DNA/RNA structure.
Lymphoma
B-cells and epithelial cells
dsDNA genome, 120-180nm, enveloped
What cancer does HBV cause, what type of cells does it affect and describe its DNA/RNA structure.
Hepatocellular Carcinoma
Hepatocytes
Unique DNA genome (RT), 30-42nm in diameter, enveloped
What cancer does HCV cause, what type of cells does it affect and describe its DNA/RNA structure.
Hepatocellular Carcinoma/Lymphoma
Hepatocytes and PBMC (Peripheral Blood Mononuclear cells)
Positive sense SS RNA genome, enveloped, 55-65nm
What cancer does HHV-8 cause, what type of cells does it affect and describe its DNA/RNA structure.
Kaposi’s Sarcoma
PBMC
dsDNA genome, enveloped, 120nm
What cancer does HIV-1 cause, what type of cells does it affect and describe its DNA/RNA structure.
Kaposi’s Sarcoma
CD4+ T-cells
Positive sense ss RNA (RT), enveloped, 120nm
What cancer does HPV cause, what type of cells does it affect and describe its DNA/RNA structure.
Cervical Cancer
Basal cells from stratified epithelium
dsDNA genome, non-enveloped, 55nm.
What cancer does HTLV-1 cause, what type of cells does it affect and describe its DNA/RNA structure.
Adult T-Cell Lymphoma
CD4+ T-cells
Positive sense ss RNA (RT), enveloped, 100nm
What cancer does MC Polyoma Virus cause, what type of cells does it affect and describe its DNA/RNA structure.
Merkel Cell Carcinoma
No clear cell tropism
dsDNA non-enveloped, 45-55nm
What is Kaposi’s Sarcoma?
Cancer affecting the lymph nodes and the skin – especially found in immuno-compromised individuals
What is HBsAg?
What it is a differential for?
HBV antigen
Hepatitis B
What is meant by the Cirrhotic Stage?
Cirrhosis is an abnormal liver condition in which there is irreversible scarring of the liver.
Which one out of HBV and HCV has a readily available and succesful vaccine?
HBV
What is the difference in type of genome in HBV compared to HCV?
HBV - DNA Virus
HCV - RNA Virus
Lamivudine is an example of a drug used to treat HBV, what does it do?
Lamivudine is a reverse transcriptase inhibitor.
Why is Lamivudine effective for HBV?
HBV’s genomic structure is that of 2 retroviruses packaged together with a RT gene.
What type of Lymphoma is HCV strongly associated with?
B-cell Non Hodgkins lymphoma (NHL)
Significant but lesser association with other benign and malignant B-cell neoplasia’s, including multiple myeloma and CLL (leukaemia)
What characteristic does HCV share with HIV-1 that makes it particularly elusive to the immune system?
Rapid resistance to Neutralising Antibodies (Nabs)
Protective vaccine based on Nabs very unlikely
May be susceptible to a non-neutralising therapeutic vaccine, a concept currently being explored for HIV
What is an interferon?
Interferons (IFNs) are a group of signaling proteins made and released by host cells in response to the presence of several pathogens, such as viruses, bacteria, parasites, and also tumor cells.
In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses.
What do drugs ending with the suffix -previr target?
Hep C protease inhibitor
What do drugs ending with the suffix -navir target?
HIV-1 protease inhibitor
How does Ribavirin work?
Nucleoside inhibitor - analog of guanosine, causes a capping of the sequence
Interference with mRNA replication
What drug combination gives a 95% infection cure rate for HCV?
Sofosbuvir + Simeprevir, Peginterferon-Alpha and Ribavirin.
What are the 3 groups of Herpes Virus and give an example of a virus in each group?
Alpha - HSV-1 (Cold Sores)
Beta - CMV
Gamma - EBV or HHV-8
Other than cancer what condition does EBV cause?
Infectious Mononucleosis
What does EBV do to B-cells?
Immortalise them
Converts them into a chronic activated state more like lymphoblastoid cells and may stabilise in intermediate activated states
What is EBNA-1 and what is its role?
Epstein-Barr Nuclear Antigen 1
This sequence also seems to stabilize the protein, preventing proteasomal breakdown, as well as impairing antigen processing and MHC class I-restricted antigen presentation. This thereby inhibits the CD8-restricted cytotoxic T cell response against virus-infected cells.
What is EBNA-1 and what is its role?
Epstein-Barr Nuclear Antigen 2
It contributes to the immortalisation of EBV infected cells.
