Current vaccine trends
1. Reverse genetics approach- In this artificially organism is created in vitro by using complementary DNA sequence of genome and by removing key amino acids or moieties involved in pathogenicity and virulence an attenuated virus is created. Thus mutating organism gives a virus that has low pathogenicity and used as vaccine by this approach one can study BSL3 type pathogens that can not be handled without safety precautions and BSL3 lab so this is a good alternative. 2. Recombinant DNA tech – It is very old technique but still is being used in every current vaccine. This involves expressing immunogenic proteins of pathogen in vitro using different vector systems. Baculoviruses is good example of this. 3. DNA vaccines - Some researchers are also working on DNA vaccine in which instead of protein DNA encoding immunogenic protein is injected in body. The DNA released is expressed in host like natural protein and elicits both humoral and cell mediated immunity along with memory development. But this also has many disadvantages. 4. Use of surrogate apathogenic virus-This approach involves expression of immunogenic protein of a pathogenic virus in a different apathogenic virus. For example 2 viruses of same family both similar in genetic constitution but different in virulent protein. Then pathogenic protein is removed by recombinant DNA tech by non pathogenic protein of surrogate virus. 5. Use of adjuvant- It is very common. Especially use of cytokines is a recent concept. They further immunomodulate and enhance immune response of vaccine 6. In malaria, people are developing genetically modified mosquitoes in which genes which facilitate Plasmodium multiplication are replaced resulting in Plasmodium resistant mosquitoes. 7. Virus like particles- In this instead of actual virus virus like particles are generated in lab and used as vaccine. These particles have essential protein of virus 8. For cancers, cytokines are used for killing cancerous cells. Also viruses are also used as vectors to target cancerous cell. E.g. Measles virus, NDV. Viral vectors are also used in gene therapy. 9. Subunit vaccines- It is vaccine over expressing protective antigens of microbe like surface glycoprotein, capsular antigen, coat proteins, attachment proteins etc. e.g., HA, NA of influenza virus