REVERSE VACCINOLOGY- a 'boom' in vaccination

For the last week I was bit busy with my internal exams and I couldn’t spend much time for blogging. It was really hard for me to find the time simultaneously to do the scrap and to prepare for the examination. Now, I am in the track again. This time I would like to write about a new topic, ‘Reverse Vaccinology’ which can be a boom in the field of immunization.

Vaccine is a preparation which is used to improve immunity to a particular disease. The term derives from Edward Jenner's use of cowpox ("vacca" means cow in Latin), which, when administered to humans, provided them protection against smallpox. Vaccines are based on the concept of variolation originating in China, in which a person is deliberately infected with a weak form of smallpox. The process of distributing and administrating vaccines is referred to as vaccination Vaccines can be prophylactic (e.g. to prevent or ameliorate the effects of a future infection by any natural or "wild" pathogen), or therapeutic (e.g. vaccines against cancer are also being investigated).

Conventional vaccine development requires researchers to grow microbes in the lab and harvest proteins. It could often be very fastidious and then we had to identify antigens one by one. Sometimes you might spend years after one single antigen, and traditionally the antigens we’ve been going after have been antigens that are the most abundant and the easiest to purify and identify. Having identified the antigen it would then go into vaccine development. Some microbes, such as hepatitis B, won’t grow in test tubes.

Reverse Vaccinology (RV) is one of the best examples of how Bioinformatics can boost Molecular Immunology. RV's novelty consists in starting the search for immunogenic antigens from in silico analyses of the pathogen's genome instead of culturing the microorganism . This allows scientists to save time and money while facing pathogens for which cell culture is difficult or impossible. RV potentially permits researchers to select, in addition to most in vivo expressed antigens (the easiest ones to purify), any protein encoded by the genome of a pathogen. The production of specific antibodies can boost immunity not only against extracellular pathogens, usually controlled by Th2-polarized responses (responses by a type of cytokines), but also against either obligate or facultative intracellular ones, usually controlled by Th1-polarized responses. Even these latter pathogens are susceptible to humoral immunity during the extracellular phases of their infectious cycle and are made vulnerable by antibody cross-linking that modifies the intracellular milieu through signaling.

NERVE (New Enhanced Reverse Vaccinology Environment), is a user-friendly software environment for the in silico identification of the best vaccine candidates from whole proteomes of bacterial pathogens.The software integrates multiple robust and well-known algorithms for protein analysis and comparison. Vaccine candidates are ranked and presented in an html table showing relevant information and links to corresponding primary data. In reverse vaccinology, you don’t even care about the pathogen, you never see the pathogen, and you just go to the computer to generate your predictions, so you are starting from the opposite direction. With genomics basically you have, from the very beginning, access to the entire repertoire of antigens and you can find ways of screening all of them at once with the same effort that you would have used to characterize only one in the past. The genome sequence is already available for most of the pathogens, and the combination of the sequences and access to the new technologies - proteomics, microarrays and integration of all of the functional genomics - allows you to identify and characterize antigens.
.