Week 6 - viral disease Flashcards
List some common viral infections in primary care. (LO1)
- Influenza.
- HPV - Human Papillomavirus.
- HHV - Human Herpes Virus.
Describe some features of influenza. (LO1)
- Seasonal disease - peak in late december.
- Acute viral infection of the respiratory tract.
- 3 types: A, B and C.
- Type B is most common.
- Type A can also infect and be transmitted by birds.
- Highly infectious.
- Incubation period of 1-3 days before symptoms present.
- Morbidity and mortality to particularly vulnerable - older people, pregnant women, people with chronic illnesses, immunosuppressed people.
When do influenza cases peak? (LO1)
Late December. It is a seasonal disease.
Why do we need to develop a new flu vaccine every year? (LO1)
The influenza virus undergoes frequent antigenic changes.
List some complications of influenza. (LO1)
- Lower respiratory tract infection.
- This can lead to hospitalisation and even death.
List the types of vaccine given for influenza. (LO1)
- Live attenuated quadrivalent - children.
- Inactivated quadrivalent.
- Inactivated trivalent - over 65s.
Describe the management for influenza. (LO1)
Antiviral drugs - neuraminidase inhibitors:
- Oseltamivir.
- Zanamivir.
What symptoms can be caused by human papilloma virus (HPV)? (LO1)
- Hand and foot warts (commonly).
- Genital warts (women).
What diseases can human papilloma virus (HPV) lead to? (LO1)
- Cervical cancer.
- Head and neck cancer.
- Penile cancer.
- Anal cancer.
- Vaginal cancer.
What protection is available against human papilloma virus (HPV)? (LO1)
Gardasil vaccine:
- Old one protects against strains 6, 11, 16 and 18.
- UK is now moving to Gardasil 9 which protects against strains 31, 33, 45, 52 and 58 as well as the previous strains.
Which strains of human papilloma virus (HPV) cause cervical cancer? (LO1)
16 + 18
Which strains does the old human papilloma virus vaccine (Gardasil-4) protect against? (LO1)
6, 11, 16, 18.
Which strains does the new human papilloma virus vaccine (Gardasil-9) protect against? (LO1)
6, 11, 16, 18, 31, 33, 45, 52, 58.
How many types of human herpes virus (HHV) exist and what is common between them? (LO1)
- 8 types.
- All of them are retained for life once infected.
What are the 8 types of human herpes virus (HHV)? (LO1)
- Herpes simplex virus type 1 (HHV-1).
- Herpes simplex virus type 2 (HHV-2).
- Cytomegalovirus (HHV-3).
- Varicella Zoster virus (HHV-4)
- Epstein-Barr virus (HHV-5).
- Human herpes virus 6 (HHV-6).
- Human herpes virus 7 (HHV-7).
- Kaposi’s sarcoma herpes virus (HHV-8) - more recently.
Describe herpes simplex virus type 1 and 2. (LO1)
- Highly infectious.
- Cause of cold sores and genital herpes.
Describe cytomegalovirus. (LO1)
- Retained for life.
- Rarely causes issues in healthy people.
- Can cause issues in pregnant women as it can be transmitted to their babies who may develop symptoms.
- Immunocompromised people can also experience symptoms or comorbidities such as interstitial pneumonia.
Describe Varicella Zoster virus. (LO1)
- Cause of chicken pox.
- Cause of shingles upon reactivation.
- Causes shingles in those who are vulnerable - over 65 or immunocompromised people, etc.
- Can be fatal in vulnerable people.
Describe Epstein-Barr virus. (LO1)
- Can cause glandular fever - “The main symptoms of glandular fever include extreme tiredness, swollen glands in your neck and a high temperature.”
Describe Epstein-Barr virus. (LO1)
- Can cause glandular fever - “The main symptoms of glandular fever include extreme tiredness, swollen glands in your neck and a high temperature.”
- Initial infection of oral epithelial cells.
- Spreads to B lymphocytes.
- Can cause a range of diseases.
Describe human herpes virus 6 (HHV-6). (LO1)
Can cause Roseola Infantum in children - rash.
Describe human herpes virus 7 (HHV-7)/reactivated HHV-6. (LO1)
- Can cause Pityriasis Rosea.
- Can be itchy but usually resolves itself.
Describe what is meant by immunisation. (LO2)
The process by which a susceptible individual is rendered immune to an infection.
What are possible aims of immunisation? (LO2)
- Preventing symptoms.
- Eradicating disease.
What is meant by passive immunisation? (LO2)
The transfer of pre-formed antibodies to a susceptible individual giving temporary protection from infection.
Give some examples of passive immunisation. (LO2)
- Occurring naturally - e.g. mother to baby via placenta and breastmilk.
- Normal immunoglobulin - e.g. hep A, measles.
- Specific immunoglobulin - e.g. hep B, rabies, varicella zoster, tetanus.
- Monoclonal antibodies - e.g. respiratory syncytial virus (RSV), SARS-CoV-2 (COVID-19).
What is meant by a live attenuated vaccine? (LO2)
- A vaccine that is traditionally generated by serial passage in tissue culture.
- Weakened pathogen due to how they are cultured.
- Using serial passage means the pathogen adapts to that type of medium so has difficult replicating in other mediums such as human tissue.
Give some examples of live attenuated vaccines. (LO2)
- BCG TB vaccine.
- MMR vaccine.
- Chickenpox and Zostavax shingles vaccine (VZV).
- Rotavirus vaccine (oral).
- Sabin vaccine (oral polio).
- Yellow fever vaccine.
- Typhoid vaccine (oral).
- Influenza vaccine (intranasal).
What are the advantages of live attenuated vaccines? (LO2)
- The pathogen replicates in the recipient and so triggers an excellent immune response compared to other types of vaccine.
- The vaccine closely resembles the infection - e.g. the polio and rotavirus vaccines are given orally and so trigger immune responses in the mucosal tissue of the GI system which prepares the body for infection as these are the tissues usually infected by the pathogen.
What are the disadvantages of live attenuated vaccines? (LO2)
- Potential for reversion - the pathogens, especially in oral polio and oral rotavirus vaccines replicate and can be shed in faeces and spread to other individuals.
- Potential for sustained vaccine strain infection.
- Not suitable for everyone - contraindications for immunocompromised people, e.g. HIV positive patients, undergoing active cancer treatment, organ transplant immunosuppression, chronic autoimmune disease, pregnant women (risk of neonatal infection).
What is meant by an inactivated whole cell vaccine? (LO2)
A pathogen killed by chemical or physical process before being introduced in people.
Give some examples of inactivated whole cell vaccines. (LO2)
- Inactivated polio (Salk).
- Hepatitis A.
- Rabies.
What are the advantages of inactivated whole cell vaccines? (LO2)
- There is NO risk of infection since the pathogen is dead and no potential for replication.
- Therefore, can be given in immunocompromised individuals and pregnant women.
What are the disadvantages of inactivated whole cell vaccines? (LO2)
- Since the pathogen cannot replicate, the pathogenic load is reduced and there is a weaker immune response to the vaccines.
- Therefore, immunity is not as strong compared to live vaccines.
What is meant by an inactivated toxin (toxoid) vaccine? (LO2)
Toxins from the pathogen chemically treated (e.g. with formaldehyde) to eliminate toxicity whilst maintaining immunogenicity.
Give some examples of inactivated toxin (toxoid) vaccines. (LO2)
- Diphtheria.
- Tetanus.
List the two types of subunit vaccines. (LO2)
- Recombinant subunit vaccines.
- Chemically purified subunit vaccines.
What is meant by a recombinant subunit vaccine? (LO2)
A specific viral protein produced in a heterologous expression system (artificially produced in either yeast cells or insect cells).
Define heterologous. (LO2)
Having a different relation, relative position or structure.
Give some examples of recombinant subunit vaccines. (LO2)
- Hepatitis B.
- Papillomavirus (HPV).
What is meant by a chemically purified subunit vaccine? (LO2)
Certain proteins are extracted directly from the pathogen and purified.
Give some examples of chemically purified subunit vaccines. (LO2)
- Acellular pertussis.
- Influenza.
What is meant by a polysaccharide vaccine? Why is it not an ideal vaccine and what is given instead? (LO2)
- The polysaccharide is a long repeated chain which generates a T cell independent immune response due to the length of the polysaccharide chain.
- When B cell receptors bind the polysaccharide chain, multiple receptors from the same B cell can bind due to the chain being so long.
- This leads to cross-linking of the B cell receptors and an immune response leading to antibody production.
- T cell involvement is required for memory cell formation and due to the cross-linking, there is no T cell action so there’s a reduced production of memory cells.
- To combat this, conjugated polysaccharide vaccines were produced.
Give some examples of polysaccharide vaccines. (LO2)
- Some meningococcal vaccines.
- Some pneumococcal vaccines.
- Salmonella.
What is meant by a conjugated polysaccharide vaccine? (LO2)
- A T cell dependent immune response is required for memory cell production.
- To attract T cells, the polysaccharide chain is conjugated to proteins which can trigger a T cell response.
- This converts the immune response to the polysaccharide vaccine to a T cell dependent response which gives better LONG-TERM immunity.
- An example of a conjugated protein is the diphtheria toxoid.
Give some examples of conjugated polysaccharide vaccines. (LO2)
- H. influenzae.
- Pneumococcal.
- Meningococcal.
Why are polysaccharide vaccines not given to children and what is given in its place? (LO2)
- Polysaccharide vaccines are poorly immunogenic in children due to the T cell independent immune response.
- A conjugated polysaccharide vaccine is given instead.
What types of vaccines have been made for the SARS CoV-2 (COVID-19) virus? (LO2)
- Adenovirus vector.
- mRNA vaccine.
What is meant by an adenovirus vector vaccine (COVID-19)? (LO2)
An adenovirus is engineered to remove the replication genes and are implanted with a transgene of interest.
The transgene used is the gene for the spike protein which has been seen in almost all variants of COVID-19 (except omicron which has a mutated spike protein).
Give an example of the adenovirus vector vaccine (COVID-19). (LO2)
AstraZeneca COVID-19 vaccine.
Explain how the adenovirus vector vaccine (COVID-19) is made and how it works. (LO2)
- Replication genes removed from adenovirus molecule so it cannot replicate in humans.
- Viral transgene (gene from the pathogen of interest) is inserted into the adenovirus nuclear material so transgene proteins are produced by adenovirus.
- When vaccine is given, the adenovirus produces COVID proteins but doesn’t replicate.
- When an immune response destroys the adenovirus, it also produces antibodies to the COVID proteins.
Give some examples of the mRNA vaccine (COVID-19). (LO2)
- Pfizer COVID-19 vaccine.
- Moderna COVID-19 vaccine.
What are adjuvants and what is their role in vaccines? Give some examples. (LO2)
- Adjuvants are agents that stimulate the immune system.
- Their role in vaccines is to increase the number of antibodies and the longevity of immunity.
- Commonly used adjuvants: aluminium, hydrogen peroxide.
Explain how the mRNA vaccine (COVID-19) is made and how it works. (LO2)
- The vaccine contains lipid nanoparticules carrying the COVID protein mRNA.
- The mRNA can escape into the cytosol of the host cells and can be translated to make the COVID-19 spike protein.
- The COVID spike protein is exposed on the host cell surface which triggers an immune response, producing antibodies to the COVID antigen.
Why are adjuvants beneficial? (LO2)
- The function of adjuvants is linked to theit ability to sequester/isolate antigens and cause inflammation.
- More recent examples include monophosphoryl iipid A, oil-water emulsion of squalene and phosphoguanine.
- The development of new adjuvants allows for modulation of the type of immune response to a vaccine.
Describe the common adverse effects linked to vaccines. (LO2)
- Related to either the pathogen or other components of the vaccine.
- Most commonly local reactions, e.g. pain, swelling, redness.
- General systemic effects: headaches, fever, malaise.
- Some vaccines cause rashes - MMR, VZV.
- Anaphylaxis is rare.
List some more severe side effects of vaccines. (LO2)
- Yellow fever - encephalitis.
- Rubella - arthropathy, thrombocytopenia.
- BCG vaccine - osteitis.
- Rotavirus vaccine - risk of intussusception.
List some more severe side effects of vaccines. (LO2)
- Yellow fever - encephalitis.
- Rubella - arthropathy, thrombocytopenia.
- Osteitis - from BCG vaccine.
- Risk of intussusception from rotavirus vaccine - parents are encouraged to maintain good hand hygiene when changing nappies since they can catch the virus through faeces causing a GI infection.
Intussusception is the twisting of the bowel, leading to obstruction.
List some containdications for vaccinations. (LO2)
- History of anaphylaxis to previous vaccine/vaccine component.
- Immunosuppression.
- Pregnancy.
Why would an immunisation be deferred? (LO2)
- If the patient is acutely unwell.
- If other vaccines have been given recently.
- If the patient is on immunoglobulin therapy.
What are two types of immunisation failures? (LO2)
- Primary vaccine failure.
- Secondary vaccine failure.
What is meant by primary vaccine failure? (LO2)
No immune response to the vaccine.
List some possible reasons for primary vaccine failure. (LO2)
Vaccine factors: - Administration error. - Manufacturing error. - Incomplete strain coverage. Host factors: - Immunodeficiency. Inappropriate vaccine schedule.
What is meant by secondary vaccine failure? (LO2)
Immunity develops initially but wanes with time.
Briefly describe the innate immune response to vaccination. (LO2)
- 1st line defence.
- Not specific.
- No memory.
- Relies on interactions between pattern recognition receptors (PRR) and PAMPs.
- Comprises of mechanical barriers, proteins, cells (APCs, NK cells).
Briefly describe the adaptive immune response to vaccination. (LO2)
- Delayed.
- Specific to the pathogen.
- Has memory.
- Comprises of B cells (antibodies), T cells (CD4 helper, CD8 cytotoxic).
What is the function of booster vaccinations? (LO2)
Increases the number of antibodies and memory cells by reintroducing the pathogen and triggering a second immune response.
Viruses have mainly been classified according to which three properties? (LO3)
- Historical classification by host - e.g. humans, plants, animals.
- Classification according to disease or target organ - e.g. respiratory, enteric, hepatitis.
- Classification according to vector - e.g. arboviruses, avian viruses.
N.B. Arbovirus - vector is an arthropod, e.g. mosquito, ticks, etc.
Molecular biology allows us to classify viruses according to which properties? (LO3)
Genetic sequence and biophysical structure.
How are viruses classified according to taxonomy? (LO3)
- Virus Order.
- Virus Family.
- Virus Subfamily.
- Type species.
- Morphology.
- Genetic material (DNA vs RNA).
- Envelope.
List some important viral species. (LO3)
- Human herpes virus.
- Human papillomavirus.
- Human adenovirus.
- Hepatitis viruses.
- Human rotavirus.
- Measles.
- Influenza.
By which property does the Baltimore system classify viruses? (LO3)
This system classifies by nuclear material.