Presentation on theme: "Viral Infection Detection. Clinical examinations & findings Antibody detection Electron Microscopic: SEM & TEM Molecular assays: PCR Detection of viral."— Presentation transcript:
Different interactions between two different viruses in a cell Recombination (based on Crossing over) - between HSV1 & HSV2 Reassortment - between Influenza viruses Complementation - Rescue of a lethal mutant with a defined genetic sequence of other virus Transcapsidation - Pseudoviruses
Cell transformation Changes in cellular growth, cellular morphology, antigenic compounds. Oncogenic viruses can be carcinogen (causing malignant tumors) and make cells to transform.
Tumor viruses Why some viruses are considered the causative of tumors? -Biological criteria for causal association of viruses with tumors: The presence of virus in tumor tissues The presence of virus before disease onset Viral persistence The location of virus at appropriate sites Prevention of the disease by prevention of viral infection
Human Oncogenic viruses Human Oncogenic RNA viruses Retroviruses: HTLV-1 & HTLV-2, HIV: Kaposi’s sarcoma Human Oncogenic DNA viruses Human Hepatitis B virus: Hepatocellular carcinoma Herpesviruses: Epstein-Barr virus: Burkitt’s Lymphoma/ Epstein-Barr virus: Nasopharyngeal Carcinoma Herpesviruses: Herpes Simplex virus Type 2: Cervical intraepithelial neoplasia Herpesviruses: Human Cytomegalovirus: Cervical tumors/ Human Papillomaviruses: types 18, 16, 33: Cervical cancer
Tumor Repressor Genes (Anti-oncogenes) They are normally oncogene regulators. If repressed (e.i. by a virus promoter) Activating the relevant oncogene Causing oncogene products Cell transformation
Cellular Oncogenes (c-onc genes) Normally inactivated. If disregulated or mutated, then causes transformation in the cell by oncogene products.
Example: Retinoblastoma (Rb) gene is one of these tumor repressor genes which regulates the pass of the cells to S stage of the cell cycle. Mutation of Rb gene by some viral promotors transforms the cell.
Growth factors Signaling proteins DNA binding proteins and other regulatory proteins Cellular receptors