you will be asked to consider 3 viral diseases for which there is currently not

Question

you will be asked to consider 3 viral diseases for which there is currently not a human vaccine. They are as follows, with a link to the CDC website that will provide you with an appropriate background regarding each disease.

1.) Chickungunya:  https://www.cdc.gov/chikungunya/ (Links to an external site.)

2.) MERS:  http://www.cdc.gov/coronavirus/mers/index.html (Links to an external site.)

3.) Zika:  https://www.cdc.gov/zika/ (Links to an external site.)

Your final will be in two parts.

Part 1: As the new director of the CDC, you are empowered to petition congress and the president for funds to develop a vaccination program for any of these viral diseases, but you realize that you will likely only get one. So you will chose the one that you think will make the greatest positive impact on the health and well-being of the citizens of the United States.

section A: For the one you chose, you will then fund one major strategy for development (attenuated, inactivated, subunit, or DNA). Which strategy do you choose? Justify your choice by comparing the pros and cons for each of the four strategies as they might pertain to your chosen virus. Be sure you cite the advantages and disadvantages of each approach, and why you think overall your choice is the best one.

Explanation / Answer

Please find the answers below:

Part 1)

Although all of the viral infections i.e. chikungunya, MERS and Zika are clinically severe infections which require immediate attention and action, the severity of MERS remains maximum. Whereas Chikungunya and Zika infections can be somewhat clinically preventive in nature, MERS infection remains highly life threatening in nature. The number of deaths reported by the MERS infection are also maximum. Also, unlike Zika and Chikungunya infections, MERS can be transmitted from an infected person directly to another person whereas other two diseases require an invertebrate insect host for their subsequeny transmission. Thus, owing to high infectivity of MERS and potential life-threatening effects, it would be highly likely that a vaccine producing programme chooses MERS as the target disease.

Part 2) The nature of vaccine:

There can be four types of vaccines which could be produced against a pathogen i.e. live attenuated, inctivated, subunit or DNA type. The pros and cons of these strategies are given as below:

1. Live attenuated vaccine: This type of vaccine is produced by keeping the pathogen live but removing its virulence producing factor for example by removing surface antigens etc. This causes attenuation of the virulence of the strain but its antigeniciy is maintain. When this vaccine is injected in a patient, it elicits a mild immune response but does not cause infection and provides a chance to host immune response to develop or acquire immunity against this infection. This causes immediate production of antibodies against the actual incidence of any subsequent infection by the similar pathogen.

Pros: The methodology is highly potent in nature because it generates memory T-cells against any infection and provides natural gain of immunity to the host to evade any subsequent infection.

Cons: There are reported cases which show failure of appropriate attenuation of the pathogen and onset of disease in the patients. Since vaccines are produced at large scales, such incidences can be cause immediate and high rates of motality.

2. Inactivated vaccine: Unlike live attenuated vaccine, an inactivated vaccine is produced by complete inactivation of the pathogen and its subsequent injection into the host to elicit an antigenic response. Since the virulence of the pathogen has been accompanied with its complete inactivation such as dead viral particles/bacterial cells, they generate mild antigenic response in the host as compared to live attenuated vaccines.

Pros: These types of vaccines also produce memory T-cells against any infection and thus protect the host from subsequent infections.

Cons: Since the pathogen is completely inactive or dead, it sometimes fails to elicit the antigenic response in host and is eliminated by host immune response as a normal foreign particle.

3. Subunit vaccine: These vaccines are based upon the fact that a surface antigen/part of the pathogen cell-structure is responsible for generation of antigenicity in the host. These parts are simply isolated and injected into the host so that antigenic response might be elicited without causing infection. This generates memory T-cells and prevents infection subsequently.

Pros: The methodology is highly safe as compared to live-attenuated vaccines or inactivated vaccines and does not cause any cases of infection.

Cons: It remains highly difficult to identify and isolate sufficient amount of antigenic subunits from the pathogen particles and requires expertise.

4. DNA vaccines: The third generation DNA vaccines are those vaccines which are based upon the fact that the genetic sequence of the pathogen is responsible for onset of antigenicity and infectivity of the pathogen inside a host. Thus, production of specific DNA against the infective region of the pathogen makes them highly potent and specific in nature. The complementary DNA is direclty injected into the host and thus vaccinated.

Pros: Highly flared host antigenic response in recorded and this prevents any subsequent chances of infection without any harm to the host.

Cons: Requires extensive research and development and expertise.

Thus, the above given information suggests that it would be best to develop a DNA vaccine against the MERS infection because it is most safe among the four and gives maximum protection against the infections.

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