Virology

Question 1

What are viruses?

Answer 1

Obligate intracellular pathogens

They are unable to replicate without a host cell, generate their own ATP and translate mRNA into protein.

They are bundles of genetic material surrounded by a protein capsid.

Question 2

Transmission of viruses include…

Answer 2

Respiratory - influenza, rhinovirus
Faecal-oral - enterovirus, polio
Bodily fluids - hepB, Ebola
Sexual transmission - HIV, hepC
Vectors - rabies, yellow fever virus

Question 3

Baltimore classes

Answer 3

1. dsDNA
2. ssDNA
3. dsRNA
4. ssRNA+
5. ssRNA-

Question 5

Rhinovirus

Classification, different types, transmission, symptoms, what does it do

Answer 5

Non-enveloped, ssRNA+, class 4.

Type A and B bind to ICAM-1, whereas type C binds to CDHR3.

Transmission: droplets
Symptoms: mucus, sore throat, headache

Loosens epithelial tight junctions between cells allowing entry of other organisms into the cell.

TLR2 is the main receptor which binds to rhinovirus activating an immune response.

Question 6

Respiratory Syncytial Virus

Classification, what is it, transmission, symptoms, Syncytium

Answer 6

Enveloped, ssRNA-, class 5.

Respiratory disease in infants which causes bronchiolitis.

Transmission: droplets
Symptoms: fever, cough, difficulty breathing

Syncytia- appears hours after infection of RSV, followed by loss of function of cilia and death of epithelia, merging cells into a giant syncytium.

Question 7

Herpes Simplex Virus

Classification, different types, transmission, symptoms, what does it do

Answer 7

Envoloped, dsDNA, class 1

Two types: HSV1 and 2 (oral & genital)

Transmission: sexual
Symptoms: ulcers

Viral DNA is inserted into the nucleus and host cell polymerase II transcribes the viral genes.

Question 8

Yellow Fever Virus

Classification, transmission, symptoms, what does it do

Answer 8

Envoloped, ssRNA+, class 4

Transmission: vectors
Stage 1: fever, muscle pain, headache, nausea
Stage 2: 15% enter this phase, fever, vomiting, bleeding, 50% mortality

Pathway: virus enters the cell by binding to TIM/TAM receptors. RNA can immediately be transcribed to protein in the ER.

Question 9

Ebola

Classification, structure, transmission, symptoms

Answer 9

Envoloped, ssRNA+, class 4

Has a helical nucleocapsid and spiked glycoproteins on surface

Transmission: bodily fluids/blood
Symptoms: fever, fatigue, aches, exhaustion. Severe cases show internal bleeding.

Question 10

Burkitt’s lymphoma

Answer 10

Fastest growing human tumour, treatable using chemotherapy.

Question 11

Rotavirus

Classification, transmission, symptoms, what does it do

Answer 11

Non-enveloped, dsRNA+, class 3

Transmission: faecal-oral
Symptoms: diarrhoea, vomiting, fever

2 main mechanisms:

1. Virus induced lysis causes disruption of intestinal villi and malabsorption
2. NSP4 (on the virus) stimulates calcium release, which stimulates the nervous system to release chloride ions and water into the intestines. Affects water balance.