AIDS vaccine

AIDS is a relatively terrible infectious disease, and in current clinical medicine, there is no good and effective method to treat AIDS. However, AIDS can be prevented through certain methods, such as injecting HIV vaccine, which is a relatively effective way to prevent AIDS. Below, we will introduce in detail several types of AIDS symptoms.

1. Inactivated HIV vaccines and live attenuated HIV vaccines

In the prevention of many infectious diseases, inactivated vaccines or live attenuated vaccines against pathogens are used to prevent disease infection, because such vaccines can mimic biologically active viruses, present entire virus particles to the immune system, and cause a wide range of immune effects. Scientists have tried to use the same approach to prevent HIV infection. Some test results also prove that this vaccine injected into the body can turn the patient's serum HIV antigen to negative and slow down the progression of the disease.

But some people have expressed doubts about the safety of the vaccine, worrying that it may cause infection and lead to adverse consequences. Studies have shown that vaccinating macaques with a live naturally attenuated simian immunodeficiency virus (SHIV) strain can prevent virulent SIV strains from causing disease in adult and newborn macaques, but cannot prevent viral infection. It has been difficult to prove whether the inactivated HIV vaccine can effectively induce a cellular immune response in the body. Many researchers hope to create a mutant defective strain of HIV by deleting genes essential for its replication so that it can induce a strong immune response without causing people to contract AIDS, but no effective research results have been achieved yet.

2. Subunit vaccines

Subunit vaccines are recombinant viral membrane protein monomers or polypeptides. It is composed of non-infectious particles of one or more HIV proteins and packaged retroviral nucleic acid sequences, so it has good safety. The recombinant gp120 protein vaccine developed by Vax Gen in the United States is the only HIV-1 vaccine that has entered Phase III clinical trials in humans. However, since the vaccine is a monomeric recombinant protein, the spectrum of neutralizing antibodies it stimulates is narrow and its attack power against wild strains of HIV-1 is limited. Therefore, in order to improve the protective ability of this type of vaccine, it is necessary to continue to develop recombinant glycoproteins that are close to natural HIV-1 and to further understand the membrane protein structure and immune invasion mechanism.

3. Live vector virus protein vaccine

The genes encoding viral proteins are inserted into the genomes of other live viruses or cells and used to infect animals or humans, so that the foreign genes are expressed in the host cells, which can produce an immune response to the gene products and vectors. Live viral vectors include vaccinia virus, baculovirus and adenovirus. The poxvirus vaccine has been studied the most. Poxvirus vaccines replicate in the cytoplasm of infected host cells and are non-carcinogenic. Such vaccines can induce the body to produce cellular immunity and humoral immunity and are easy to produce and preserve. However, attention should still be paid to its safety issues. HIV infection causes immunosuppression in the body. If the vector mutates in the body, it will threaten the patient's life. It has been reported that the canarypox virus vector vaccine that has entered Phase II clinical trials has been shown to produce long-lasting humoral and cellular immune responses. Because avian poxvirus does not have a complete replication cycle in human cells, its safety is relatively good.

4. DNA vaccines

DNA vaccines are called the third generation vaccines after whole pathogen vaccines and genetically engineered recombinant protein vaccines. They involve inserting and expressing plasmid DNA of the target antigen gene into the body's cells through various transfer pathways, and using the host cells' expression and processing to synthesize antigen molecules. In 1992, Tang et al. first directly inoculated plasmid DNA encoding foreign proteins through mouse skin and found that this immunization method could also induce the body to produce antibody responses, confirming that "naked" DNA can be used as an immunogen through antigen expression. After naked plasmid DNA is injected into the body, it can enter cells and continuously express exogenous proteins, thereby effectively stimulating humoral immunity and cellular immunity. Their effectiveness has been demonstrated in macaque monkey trials, where they can often prevent SIV-induced AIDS. Through this direct in vivo injection method, the antigenic epitopes of the immunizing protein are produced in a way that can be naturally recognized by the host receptors, and the presentation of the antigenic peptides is similar to natural infection. This feature is particularly important for the protective immunity induced by conformational antigenic epitopes.

This vaccine has both the effectiveness of live attenuated vaccines and the safety of subunit vaccines. It can continuously express antigen proteins just like live virus bodies, and can also easily select the required gene fragments to stimulate an ideal immune response. Since this vaccine can express antigens in body cells and has good immunogenicity, it can induce humoral immune response and strong cytotoxic response. At the same time, it can be made into a multivalent vaccine, which is easy to modify to adapt to prevalent strains and easy to prepare and preserve, making it particularly suitable for developing countries. Based on the above advantages, DNA vaccines are now a hot topic in the development of AIDS vaccines, and some HIV DNA vaccines have entered the human trial stage.