Viruses In Heath And Disease Flashcards
(24 cards)
What are the useful properties of viruses
• Immune Response: Viruses naturally trigger appropriate immune responses.
• Gene Delivery: They are efficient gene-delivery vehicles.
• Cytopathic Effect: Many viruses can kill cells (useful for targeting diseased cells).
• Genetic Manipulation: Some viruses are easy to genetically modify (recombinant viruses).
• Targeted Delivery: Can be engineered to target specific cells.
• Gene Expression: Viruses can drive powerful gene expression.
• Foreign Genes/Proteins: Can carry and express foreign genes.
• Attenuation: Harmful components can be removed to create attenuated (weakened) viruses for vaccines.
How did Jenner immunise against smallpox
Jenner used cowpox to immunize against smallpox.
Why does the smallpox vaccine protect against monkeypox
Related Virus: Monkeypox virus is related to smallpox.
• Cross-Protection: Smallpox vaccine protects against mpox.
How do vaccines protect against viruses
• Immune Priming: Vaccines induce memory B and T cells.
• Rapid Response: Subsequent exposures lead to rapid, effective immune responses.
• Herd Immunity: Vaccination reduces disease transmission.
What are the 4 main types of vaccine
Live Attenuated: Weakened viruses (e.g., MMR, Sabin polio, influenza)./ Heterologous: Related but less virulent viruses (e.g., vaccinia for smallpox)
Killed Whole Virus: Inactivated viruses (e.g., Salk polio).
Subunit: Purified viral components or recombinant proteins (e.g., HBV, HPV).
Gene Delivery: Vectors expressing pathogen genes (e.g., COVID-19 spike protein).
What are advantages and disadvantages of live vaccines
Live Vaccines: Strong, long-lasting immunity, humoral and cellular response; risk of reversion; unsuitable for immunosuppressed.
What are the advantages and disadvantages of killed/subunit vaccines
Killed/Subunit Vaccines: Safer, but may induce weaker or only antibody responses, cell mediated responses often required for immunity
What are recombinant viruses and how are they used as vaccines
Recombinant Viruses as Vaccines
• Concept: Insert immunogenic genes from pathogenic viruses into safe viral vectors (e.g., vaccinia, adenovirus).
• Benefit: Induce desired immune responses when live vaccines are not feasible.
How are viruses used in gene expression
Laboratory Use
• Promoters/Enhancers: Viral promoters (e.g., HCMV, SV40, HIV LTR) drive strong gene expression.
• Vectors: DNA plasmids with viral promoters used for gene expression in cells.
• Cloning Process: Insert gene of interest (cDNA), propagate in bacteria, transfect into target cells.
why are viruses used as vectors
Why Use Viral Vectors?
• Efficiency: Viruses infect cells more efficiently than chemical transfection.
• Tropism: Can target specific cell types.
• Gene Delivery: Deliver genes to cytoplasm/nucleus; expression can be transient or permanent.
What are the two different gene therapy approaches
Ex vivo and in vivo
What is in vivo gene therapy
In vivo: Deliver gene directly into the body.
What is ex vivo gene therapy
Ex vivo: Modify cells outside the body, then reintroduce.
What is CAR-T gene therapy
T cells isolated, genetically modified (e.g., with lentivirus), and reintroduced to target cancer.
What are adenoviral vectors
A common vector for gene expression in research laboratories
•Is the vector used in delivering Covid vaccines
What are the advantages of adenoviral vectors
Advantages: Easy to manipulate, infect many cell types, high gene expression.
What are the disadvantages of adenoviral vectors
Disadvantages: Limited gene size (~8 kb), immunogenic (single use), transient expression.
Immunological Response: Strong immune reaction, pre-existing immunity, toxicity at high doses.
Describe 2 functions of adenoviral vectors
• Modification: Remove essential genes (e.g., E1) to make replication-incompetent.
• Packaging: Use helper cell lines to supply missing proteins.
What are Adenoviral-associated virus (AAV) vectors
Adeno-associated virus (AAV) vectors are engineered viral tools derived from non-pathogenic parvoviruses, widely used in gene therapy for delivering therapeutic genes to target cells
What are the pros and cons of AAV vectors
• Pros: Low immunogenicity (repeat dosing), broad cell range, stable expression, not linked to disease.
• Cons: Small gene size limit (~4.7 kb), some pre-existing immunity, production cost.
Describe gene therapy for obesity and metabolic disease
Current Treatments
• Lifestyle: Diet, exercise.
• Drugs: GLP-1 agonists (Ozempic, Wegovy), metformin.
Gene Therapy Rationale
• Benefits: Single administration, long-term effects, potential for chronic disease management.
• Challenges: Mostly in animal models, ethical/cost concerns.
Key Targets
• Leptin: Hormone regulating appetite; deficiency leads to obesity (ob/ob mouse model).
• FGF21: Delivered via AAV in mice; increases insulin sensitivity, reduces fat and liver disease.
FGF21 Therapy Results
• Effects in Mice: Reduced weight gain, improved liver health, lower serum triglycerides/cholesterol/insulin, lower inflammation.
What is CRISPR
Bacterial defense system adapted for targeted gene editing.
What are the applications of CRISPR
Modify genes/promoters, treat monogenic diseases, regulate metabolism-related genes.
What are adenoviruses and how are they used
Adenovirus vectors are genetically engineered viruses derived from adenoviruses, commonly used to deliver therapeutic genes into human cells for gene therapy, vaccine development, and cancer treatment.
How Adenovirus Vectors Work
• Genetic Modification: Key viral genes (often E1 and sometimes E3) are deleted to prevent the virus from replicating in normal human cells. These deleted regions are replaced with a cassette containing the therapeutic gene or antigen of interest.
• Gene Delivery: The modified adenovirus infects target cells and delivers its DNA, which remains episomal (outside the host genome), allowing for robust but transient expression of the therapeutic gene.
