Lecture A10 - Some Important Viruses Infecting Mucosal Sufaces

Question 1

Name some non-enveloped viruses that infect mucosal surfaces?

Answer 1

Rotavirus - dsDNA infects the digestive tract.
HPV - dsDNA infects the urogenital tract.
Norovirus - ssRNA infects the digestive tract.
Poliovirus - ssDNA infects the digestive tract.
Trichomonasvirus - dsRNA infects the urogenital tract.

Question 2

Name some enveloped viruses that infect mucosal surfaces.

Answer 2

HIV - ssRNA infects the urogenital tract.
SARS-CoV-2 - ssRNA infects the respiratory tract.
Influenza - ssRNA infects the respiratory tract.

Question 3

What viruses have effective vaccines?

Answer 3

Poliovirus, HPV, coronaviruses.

Question 4

What vaccines have variable efficacy?

Answer 4

Influenza, rotavirus

Question 5

What infections have no vaccines available?

Answer 5

HIV, norovirus

Question 6

What are the 6 core features of effective vaccines?

Answer 6

Safe
Protective
Gives sustained protection
Induces neutralising antibody
Induces protective T cells
Practical considerations (low cost, ease of administration etc).

Question 7

What type of vaccine is usually required for the digestive tract?

Answer 7

Oral.

Question 8

What are the different types of administration for parenteral vaccines?

Answer 8

Intramuscular, subcutaneous, intravenous and intradermal.

Question 8

What are the different delivery methods of vaccines?

Answer 8

Intranasal, sublingual, oral, rectal, intravaginal, parenteral.

Question 9

How can systemic IgG and mucosal IgA be produced?

Answer 9

Via the combination of the mucosal and parenteral vaccines.

Question 10

What is the difference between mucosal and parenteral vaccines?

Answer 10

Parenteral injected vaccines give systemic immune responses.
Mucosal vaccines give rise to both mucosal and systemic immune responses.

Question 11

Why might the urogenital and lower respiratory tracts may also be effectively treated by parenteral vaccines?

Answer 11

These mucosa are permeable to serum IgG.

Question 12

What is a live attenuated vaccine?

Answer 12

Specific part of the virus cloned and purified. It is then sub cloned as a slightly different version of the virus so that illness is not caused by the virus when it is administered.

Question 13

What is an inactive attenuated vaccine?

Answer 13

The virus is chemically killed (fixed) so the virus is not pathogenic but is still a whole thing that will be recognised by the immune response to stimulate a response.

Question 14

Name three examples of live attenuated vaccines, their entry route and trade name.

Answer 14

Polio (OPV) - oral - many trade names
Rotavirus (monovalent human rotavirus strain) - oral - RotaRix
Influenza (cold-adapted influenza virus reassortant strain) - nasal - FluMist.

Question 15

Describe poliovirus.

Answer 15

Non-enveloped, spherical, pseudo3 icosahedral capsid surrounding the naked RNA genome. Capsid consists of a densely packed icosahedral arrangement of 60 promoters, each consisting of 4 polypeptides (VP1, VP2, VP3, VP4). VP4 is located on the internal side of the capsid.
ssRNA.

Question 16

Describe rotavirus.

Answer 16

Non enveloped icosahedral non-turreted vision with a triple capsid structure. Intermediate capsid has a 13 icosahedral symmetry, the inner capsid has 2 icosahedral symmetry.
dsRNA.

Question 17

Describe norovirus.

Answer 17

Non enveloped capsid with 3 icosahedral symmetry. Capsid is composed of 180 VP1 proteins. Small empty virions are 23nm in diameter and would be 1 icosahedral symmetry composed of 60 VP1 proteins.
ssRNA.

Question 18

What are the 2 vaccines for polio?

Answer 18

Oral polio vaccine and the inactivated polio vaccine.
Combination of both of these vaccines basically eradicated polio from the world.

Question 19

Describe the inactivated polio vaccine.

Answer 19

No risk of vaccine related paralytic polio (VAPP).
Does not stimulate antibodies in the gut.
Protects only the immunised, no community benefits.
More expensive than the oral as requires a sterile syringe.

Question 20

Describe the oral polio vaccine.

Answer 20

Cheap and ideal for mass vaccination.
Immunological response in both the gut and systemic tissues.
Provides community benefits.
Small risk of VAPP.

Question 21

What is the 3 modes of action of neutralising antibodies?

Answer 21

Block attachment
Block endocytosis
Block uncoating.

Question 22

Describe the epidemiology of rotavirus.

Answer 22

Most important cause of diarrhoeal mortality in children below 2.
450,000 children deaths per year.
>90% of death cases due to this virus occur in Africa and Asia (resource limited contexts).
2 licensed oral vaccines.

Question 23

What is the principle effector of long-term protection against rotavirus?

Answer 23

SIgA neutralises it.
There is a role in endoscopes reducing viral replication for anti-VP6 antibodies.
Anti VP4 and VP7 antibodies support a neutralising role in the lumen.
Such antibodies reduce initial infections and interfere with ongoing infections.

Question 24

What is RotaRix?

Answer 24

An attenuated human virus vaccine for rotavirus.

Question 25

What is RotaTeq?

Answer 25

A cocktail of cattle-human hybrid virus vaccine for rotavirus,

Question 26

Why are the rotaviruses vaccines not enough on their own?

Answer 26

They have variable efficacies and are not a solution to eradicate the virus. An integrated approach of combining improved nutrition, access to clean water and better sanitation and hygiene are needed.

Question 27

Describe orthomyxoviridae.

Answer 27

Enveloped, usually rounded but can be filamentous. ssRNA Human to human transmission, animal to human transmission, human to animal transmissions. Mixing between human and animal variants can lead to the production of new types of viruses.

Question 28

What is antigenic shift?

Answer 28

Major change in influenza virus antigen due to gene reassortment

Question 29

What is antigenic drift?

Answer 29

Minor change in influenza virus antigens due to gene mutation

Question 30

Why do we need an updated vaccine for influenza each year?

Answer 30

Influenza is a highly variable virus due to antigenic shift and drift. Outbreaks occur annually due to the plasticity of the genome so constantly need an updated vaccine to be able to be effective against the new version of the virus.

Question 31

Describe betacoronavirus.

Answer 31

Enveloped, RNA genome associated with the N protein to form the nucleocapsid. ssRNA, has a membrane but it is non segmented.

Question 32

Who are more vulnerable to becoming seriously ill and die from coronavirus and why?

Answer 32

Elderly people and those with pre-existing medical conditions and people with comorbidiities. Key factor could be the loss of microbial diversity associated with ageing and with it a higher susceptibility to inflammation.

Question 33

What are some drug/antibody treatments for covid?

Answer 33

Antivirals - virus particles multiply inside the body, antiviral drugs prevents the virus from multiplying. Anti-inflammatories - immune system overreacts to the virus, anti-inflammatories calms the immune response. Antibody treatments - antibody specific to coronavirus to bind and kill it.

Question 34

What type were the 2 vaccines for covid?

Answer 34

Modified DNA virus vaccine. mRNA vaccine.