Research Progress Of Innovative Vaccines For Bacterial Infections

Vaccines for bacterial infections are still an indispensable and important scientific tool for public health and epidemic prevention. In recent years, the rapid development of frontier fields of medicine, biology, materials science and other disciplines has continuously promoted the upgrading and optimization of the varieties of vaccines for bacterial infections on the market to meet people's growing health needs. At the same time, the original bacterial vaccine has made many major breakthroughs in the extremely difficult exploration to deal with the increasingly severe super-resistant bacteria.

Upgrade and optimization of listed vaccines for bacterial infections

Streptococcus pneumoniae vaccine

Streptococcus pneumoniae is a class of gram-positive cocci with rich capsules, which usually colonize the human pharynx, mainly causing local organ infections such as pneumonia and otitis media, systemic sepsis and even death. WHO data shows that in 2008 alone, about 8.8 million children under the age of 5 died, of which 476,000 died of Streptococcus pneumoniae infection. In the early 20th century, inactivated whole-bacteria Streptococcus pneumoniae vaccines were developed in the United States, but the invention of antibiotics reduced the demand for vaccines, resulting in slow progress in vaccine upgrades. With the emergence of antibiotic resistance in the 1960s, the role of vaccines in the prevention and control of Streptococcus pneumoniae infection and drug resistance has regained attention, and has promoted the rapid development of vaccines. The abundant extracellular capsule is a key pathogenic factor of S. pneumoniae, which plays a pathogenic role by mediating bacterial adhesion and resisting the immune killing process of the host, and thus is also a key target for vaccines.

Meningococcal vaccine

Meningococcus is a gram-negative encapsulated aerobic diplococcus, mainly inhabiting the human nasopharynx, and is one of the main pathogens causing acute bacterial meningitis. Globally, 300,000 to 500,000 people are infected every year, and the fatality rate is about 40%. Among them, 10% to 20% of survivors of meningococcal infection have permanent neurological sequelae, causing a serious burden on families and society. Similar to S. pneumoniae, the capsule is its primary virulence agent and vaccine target. The meningococcal vaccines currently on the market are mainly polysaccharide or polysaccharide conjugate vaccines.

Mycobacterium tuberculosis vaccine

Tuberculosis, caused by Mycobacterium tuberculosis, is a major infectious disease that threatens the health of children worldwide. So far, BCG is the only vaccine that has been used the longest in the world to prevent TB. About 89% of children worldwide are vaccinated with BCG each year. BCG vaccination has a good protective effect on severe TB, such as miliary TB and tuberculous meningitis. However, BCG still has many deficiencies, mainly as follows: the immune protection effect on adolescents and adults is unclear, the duration of the protection effect is limited, and the protection effect of different immune methods varies greatly. For some immunocompromised newborns, early BCG vaccination can cause BCG disease, which can lead to death in severe cases. Therefore, it is imperative to study a new type of Mycobacterium tuberculosis vaccine.

Research progress of original vaccines for bacterial infections

Staphylococcus aureus vaccine

Staphylococcus aureus is a gram-positive coccus, which is the main pathogen of nosocomial infection, war wound, and burn infection. It mainly causes skin abscesses, osteomyelitis, pneumonia, and sepsis. Methicillin-resistant Staphylococcus aureus is a typical example of its drug-resistant bacteria, causing the same number of deaths each year as AIDS. The targets of Staphylococcus aureus vaccines mainly focus on capsule, surface adhesion factor and secreted exotoxin.

Pseudomonas aeruginosa vaccine

Pseudomonas aeruginosa is a gram-negative non-fermentative bacillus with single flagella and no capsule. It is widely found in hospital environments, human skin, respiratory tract and other parts. It is one of the most common opportunistic pathogens for hospital-acquired infections. Pseudomonas aeruginosa is easy to be infected when the body's immune disorder or respiratory function is impaired, such as patients suffering from war trauma, burns, mechanical ventilation, chronic obstructive pulmonary disease, cystic fibrosis, etc. Pseudomonas aeruginosa infection can occur in any tissue and organ of the human body, among which the cornea, lung, and skin are more common.

Clostridium difficile vaccine

Clostridium difficile is a Gram-positive anaerobic bacillus that can cause intestinal infections such as antibiotic-associated diarrhea, associated colitis, and pseudomembranous colitis. Due to the emphasis on refractory diarrhea and the upgrading of detection methods, the detection rate of Clostridium difficile has increased year by year in recent years. Clostridium difficile toxin A and toxin B are the main virulence factors of the bacteria, which can cause inactivation of guanine triphosphatase, resulting in cell death and intestinal barrier function impairment, thereby triggering infectious diseases. Metronidazole, vancomycin, and fidaxomycin are the main drugs currently used to treat C. difficile infection. However, due to drug resistance and recurrence, these antibiotics have limited therapeutic effects, and other interventions such as vaccines and antibodies are urgently needed.

Conclusion

In a sense, the history of human civilization is the history of fighting against pathogenic microorganisms. Before the invention of vaccines and antibiotics, bacteria have always been the biggest threat to human health. Vaccines for bacterial infections have played an extremely important role in helping humans fight infectious diseases.