Differentiate between the following types of vaccine and give an example of each: (A) inactivated virus vaccines; (B) live-attenuated virus vaccines; (C) subunit vaccines; (D) toxoid vaccines; (E) conjugate vaccines; and (F) combination vaccines

Question

What will be an ideal response?

Answer 1

A. Inactivated virus vaccines are made of virus particles that are not able to replicate because they have been chemically or physically treated (for example by heat) in a way that inactivates the nucleic acid. Examples are Salk polio vaccine, rabies vaccine, and influenza vaccine.
B. Live-attenuated virus vaccines are made of viruses that have lost their pathogenicity and ability to reproduce efficiently in human cells through mutations accumulated as a result of growing the virus in non-human cells. Examples are Sabin polio vaccine (oral), measles vaccine, mumps vaccine, yellow fever vaccine, BCG and Salmonella typhi vaccine, and varicella vaccine.
C. Subunit vaccines are composed only of particular antigenic pathogen components known to induce protective immune responses. Recombinant DNA technology enables the production of antigenic proteins in the absence of other pathogen gene products. Examples are hepatitis B vaccine and Bexsero vaccine.
D. Toxoid vaccines are made from chemically inactivated toxins purified from pathogenic bacteria. Toxin activity is eliminated but antigenic activity is not, so an immune response is generated in the absence of pathological damage. Examples are diphtheria vaccine and tetanus vaccine.
E. Conjugate vaccines are made by covalently coupling antigenic polysaccharide found in bacterial capsules to a carrier protein (often a toxoid). This converts the otherwise T-independent bacterial polysaccharide antigen into a T-dependent antigen. T cells respond to an epitope on the protein carrier, whereas B cells respond to epitopes on the polysaccharide portion of the conjugate. This ensures that T-cell help is provided to B cells making anti-capsule antibodies. Examples include vaccines against Neisseria meningitidis, Haemophilus influenzae and Streptococcus pneumoniae.
F. Combination vaccines consist of components that stimulate protective immunity against more than one pathogen. DTP (diphtheria, tetanus, pertussis) vaccine is an example.