Virus Flashcards

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1
Q

What virus causes Chicken Pox?

A

Varicella Zoster Virus

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2
Q

What type of parasite is a virus?

A

Obligate Intracellular Parasite - must reproduce in cells - no ribosomes

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3
Q

Explain Virus structures

A

DNA/RNA (10s-100s of genes) - protein coat (capsid), surface proteins, sometime lipid envelope (avoids immune system)

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4
Q

What are 2 examples of viral testing?

A

Antigen testing - antibody derived from cells - recognise proteins(antigens) in biological samples
PCR - amplify specific nucleic acid sequence

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5
Q

What virus causes smallpox?

A

Variola major

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6
Q

How do virus infect cells?

A

Spike protein on virus binds to receptor proteins on host cell - inject nucleic acid into host cell - host replicated viral DNA - new virus assembled in cell e.g. capsid - sometimes & lipid envelope forms - host cells lyse & release virus

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7
Q

Example of viruses that spread via oral transmission

A

Hepatitis A, norovirus (2 bucket illness - emesis & diarrhoea), rotavirus (emesis), polio

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8
Q

Examples of viruses that spread via skin contact

A

HPV, Herpes Simplex Virus 1, Epstein Bar virus, Varicella-Zoster virus, Coxsackie

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9
Q

Examples of viruses that spread via sexual transmission

A

HIV, HPV, HSV-1

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10
Q

Examples of viruses that spread via droplet transmission?

A

SARS-CoV-2, rhinovirus (common cold), influenza, RSV, measles

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11
Q

Examples of viruses that spread via direct inoculation?

A

Hepatitis B, HIV, Yellow Fever virus, West Nile virus, Rabies

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12
Q

What is the average basic reproduction number?

A

Expected number of secondary infections caused by a single infected person - >1 = cases rise - <1 = cases fall

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13
Q

What is the case fatality rate?

A

Proportion of people who die from a specified disease among all positive cases over a period of time

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14
Q

Who is immune against monkeypox?

A

Anyone vaccinated against smallpox - Irish people born before 1972

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15
Q

What led to the eradication of small pox?

A

Vaccination - Jenner - inoculated with milder disease called cowpox - similar to small pox - led to immunity
Variolation - small sample from pustule placed in cut - small viral load - mild case of small pox - immunity

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16
Q

Can you be cured of Herpes Simplex Virus 1?

A

No - its a life long disease - lies dormant in neuronal cells near nucleus

17
Q

Explain HSV-1 infection?

A

Infects epithelial cells - cold sores, pustules, tingling sensation - lies dormant in neuronal cells until reactivated by stresses or when immune system compromised

18
Q

What virus causes cold sores?

A

Herpes Simplex Virus 1

19
Q

What is the effect of a Varicella Zoster Virus infection?

A

Chickenpox in youth - reactivates in elderly causing shingles - can travel to optic nerves & cause blindness

20
Q

What is a retrovirus?

A

Contains RNA & an enzyme called reverse transcriptase - viral RNA converted to DNA & inserted into host’s genome - transcription & translation occurs - virus is released via budding

21
Q

What percentage of the human genome is believed to have come from retroviruses & examples of features that they code for?

A

8% - placenta & synapses

22
Q

Give an example of a retrovirus

A

HIV

23
Q

What virus causes AIDS?

A

Human Immunodeficiency Virus

24
Q

What cells do HIV target?

A

CD4 lymphocytes (T cells)

25
Q

How fast does HIV replicate?

A

10 billion viruses per day

26
Q

How is HIV contracted?

A

Unprotected sexual intercourse (anal & vaginal), blood transfusions, needles, mother to baby (transplacentally, breast milk, birth)

27
Q

What is used to treat HIV?

A

Anti-Retroviral triple therapy - nucleosides, protease inhibitors, RT inhibitors) - costly

28
Q

Where did HIV originate?

A

mines in the Congo

29
Q

What is a zoonotic disease?

A

Disease that can be transferred from 1 specie to another - influenza, HIV, Ebola, SARS-CoV-2 - often come from bats as they have strong immune systems & can carry many diseases

30
Q

What virus causes Covid-19?

A

SARS-CoV-2

31
Q

What receptor does SARS-CoV-2 bind to?

A

ACE 2 recpetors

32
Q

How many SARS-CoV-2 virus particles can be in one droplet?

A

10,000

33
Q

Explain a SARS-CoV-2 infection

A

Spike protein stick to glycans of mucins in respiratory tract - bind to ACE 2 receptors (respiratory tract, blood vessels, intestine) - TMPRSS2 protease cleaves virus to receptor - symptoms after 2 days - phagocytes engulf virus - Antigen Presenting cells bring viral fragments to CD4 cells - stimulate the plasma cells to produce IgM antibodies first followed by IgG - IgG on repeat infection

34
Q

How can cases be measured in urban areas?

A

Quantify virions in wastewater - sample of sewage taken - sample centrifuged & RNA purified - sample lysed & RNA extracted - reversed transcribed to cDNA to allow RT-qPCR to take place