PaBi (11): vaccines for human nematodes Flashcards

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1
Q

What is the difference between monovalent and multivalent vaccines?

A

Monovalent vaccinates against one strain or organism or only contains one antigen where as multivalent vaccinates against multiple

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2
Q

What type of vaccine are nematode vaccines?

A

monovalent

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3
Q

What is the effect of hookworms and other soil transmitted nematodes on quality of life?

A

They cause morbidity rather than mortality. Affect the number of “useful” healthy days you have in your life. Many children can’t go to school and this means they have a 40% reduction in their ability to earn money so continues the cycle of poverty

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4
Q

What is the most prevalent of hookworms?

A

Necator americanus

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5
Q

What is the lifecycle of the hookworm?

A

Live for 1-2 years in the small intestine, females produce ~10,000 eggs per day which are excreted into the environment. The eggs hatch and the larva molts 3 times and burrow into the skin. They travel through the lymphatics to the lungs, up the trachea and are swallowed so they reach the small intestine.

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6
Q

What are the pathological effects of helminth infections?

A

They drink a lot of blood (~1ml per day) so can lead to severe anaemia.

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7
Q

What are the problems of using drug based control for hookworms?

A

Frequent use leads to resistance and the effects of the drug don’t last very well so people are easily reinfected if there is high numbers of the worm

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8
Q

What was the ideal hookworm vaccine?

A

Vaccinate against multiple antigens and life stages, and provide protection into adulthood

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9
Q

What were the realistic aims of creating the vaccine, since sterilising immunity was not an option?

A

To reduce the severity of the infection and reduce blood and nutrient loss

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10
Q

What hookworm stage is the dog vaccine against?

A

The third larvae stage, L3

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11
Q

What antigen is a potential vaccine candidate in humans?

A

Activation-associated secretory proteins (ASP-2) secreted from the L3

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12
Q

Why was the vaccine with ASP-2 halted?

A

In phase 1 clinical trial some people had type 1 hypersensitivity reactions so now adult worm antigens are being researched.

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13
Q

What is a promising vaccine target in the adult worm?

A

Glutathione-S-transferase which converts toxic haem into a non-toxic substance so blocking this would kill the parasite

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