Which of these may be a side effect of subunit vaccinations?

[GoGoGirl]

I know that subunit vaccines are made using genetic engineering of yeast cells. The question I'm trying to answer is:

What might be a side effect of these types of vaccinations?

A. the disease
B. a yeast infection
C. due to extraneous material
D. that the vaccine doesn't provide immunity
E. none of the above

I thought it would be D, that the vaccine does NOT provide immunity, might be a possible side effect, but someone in my class is saying that it is A. Can anyone offer any insight or hints in the right direction? Thanks!

[nanofreak]

I think your answer is D. Just read through the following paragraphs:

Subunit vaccines contain purified antigens rather than whole organisms; an example is the Bordetella pertussis antigens included in the acellular DPT vaccine. Subunit vaccines are not infectious, so they can safely be given to immunosuppressed people; and they are less likely to induce unfavorable immune reactions that may cause side effects.

The disadvantages of subunit vaccines are that the antigens may not retain their native conformation, so that antibodies produced against the subunit may not recognize the same protein on the pathogen surface; and isolated protein does not stimulate the immune system as well as a whole organism vaccine.

Other protein vaccines that induce good protective immunity are the diphtheria and tetanus toxoid components of DPT. These are toxins that have been treated to eliminate their toxicity; they are still able to induce antibodies that can neutralize the native toxins.

The effectiveness of subunit vaccines in increased by giving them in adjuvants. Adjuvants slow antigen release for a more sustained immune stimulation, bind toll-like receptors on macrophages and dendritic cells to stimulate production of inflammatory cytokines, and activate APC to express B7. Alum (aluminum salts) is a common adjuvant used in human vaccines; it aggregates proteins to make them easier for phagocytes to engulf. Pertussis toxin, one of the components of the acellular DPT, acts as an adjutant in that vaccine. Some bacterial components used as adjuvants in animals but which cause too much inflammation to be safe in humans are whole Mycobacterium tuberculosis, muramyl dipeptide from Mycobacterial cell walls, and bacterial DNA. Animal studies have demonstrated that injecting mice with Leishmania major plus IL-12 stimulates T cells and NK cells to make IFNg and induces a protective Th1 response.

[nanofreak]

The answer would have been (A) if the vaccine was an attenuated type of vaccine.

"The Sabin oral polio vaccine and the measles, mumps, and rubella (MMR) vaccine are examples of attenuated (weakened) vaccines.

To make an attenuated vaccine, the pathogen is grown in animals or tissue culture under conditions that make it less virulent.

Advantages of whole virus attenuated vaccines are that infectious virus can stimulate generation of memory cellular as well as humoral immune responses; the ability of the virus to multiply in the host means that less virus must be injected to induce protection; and use of the whole virus stimulates response to antigens in their natural conformation.

Additional advantages of the Sabin vaccine are that it can be administered orally, which is less expensive than giving injections; and oral administration induces mucosal immunity and IgA synthesis, which gives more protection at the normal site of virus entry.
Disadvantages of attenuated vaccines are that the virus may very rarely revert to its virulent form and cause disease; and live virus vaccines cannot be given safely to immunosuppressed people. Because the incidence of vaccine-acquired polio is much higher than that of naturally acquired polio in the US, vaccination recommendations changed recently so that infants will receive killed polio vaccine prior to receiving the oral vaccine. The oral vaccine is being used in the WHO polio eradication campaign."

[nanofreak]

I was sure of the answers from what I've learnt in class but for your question this link will be useful
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