HIV vaccines!Can a vaccine Cure or Prevent Aids?

Many efforts have been made to make an effective vaccine against HIV. but it is still a distant dream since the virus changes its genomic structure with each replication, thereby preventing emergence of protective immunity.

HIV infection broke out as an epidemic in parts of United States in the late seventies and spread rapidly all around the globe to result in pandemic within next 10 years. The only way to arrest this pandemic is through health education and if feasible, a vaccine. Following are the vaccines which have been tried in this regard:

• Envelope based vaccines:The envelope proteins of the virus are essential for the attachment of the virus to the vulnerable cells. Hence, vaccine directed against these proteins will prevent entry of virus particles into vulnerable cells thereby preventing the infection in the first place.
• Viral Peptides:These comprise synthetically manufactured viral proteins. their injection produces antibodies as well as memory cells that can identify these viral proteins as foriegn and destroy thm at next level of contact.
• Vector controlled vaccines:These are viral proteins that are combined with another benign virus so they are able to reach the immune cells of the body.
• DNA vaccines:These are genetically engineered vaccines that comprise more than one HIV proteins and hence can probably produce better immunity.
• Whole HIV vaccines:These comprise irradiated whole HIV and hence are supposed to be most immunogenic as they have all the viral proteins.
• Utility of vaccines:Until now, none of the vaccines have reached phase 3 trials in humans for immunoprophylaxis. Even if they do, we will still need a few years before utility of any vaccine is decided. Only evidence of utility of these vaccines comes from animal studies.

The principal problem with vaccine development today is that each region of the world has its own

strain of the virus. There is upto 40% variation in the genetic material between these strains. So,the

vaccine against one may not be useful against another. To complicate the problems further, the

virus keeps mutating rapidly so this variation in the genetic material keeps increasing. Because of

those reasons, vaccines against HIV are not likely to be available for general use in the near future.