Recently, scientists at the Center for Infectious Diseases Research at the University of Adelaide in Australia have developed a single vaccination method. It can simultaneously fight two of the world’s deadliest respiratory diseases, influenza A virus (IAV) and pneumococcal (Streptococcus pneumoniae) infection. The team says the new combined vaccine they are developing as a single vaccine that will overcome the limitations of existing flu and pneumococcal vaccines around the world.
1. Introduction to Influenza virus A
According to the hemagglutinin (HA or H) and neuraminidase (NA or N) proteins on the surface of the virus, orthomyxoviruses can be further divided into 7 genera, and Influenza A virus is one of them. Influenza A virus has been identified with 16 H subtypes and 9 N subtypes up to now. Due to the presence of viral variants, specific influenza virus isolates are further named according to virus type, site of isolation, isolation number, year of segregation, and H and N subtypes, such as A/Moscow/10/99 (H3N2). Influenza A virus can cause flu in birds and mammals. All subtypes of the genus are isolated from wild bird species, and some isolates can cause serious diseases to birds but are less harmful to humans. Sometimes, the spread of the virus from wild birds to poultry can cause an outbreak of the virus or increase the prevalence of human influenza.
The Influenza A virus genome is a single-stranded, segmented RNA and the viruses can be divided into different subtypes based on the number of hemagglutinin and neuraminidase proteins. There are currently 18 defined H antigens and 11 known N antigens. Each subtype of virus can be mutated into a series of strains with different pathogenicity, some of which cause disease to a particular species, while others cause disease in a variety of species.
2. Introduction to Streptococcus pneumoniae
Streptococcus pneumoniae, one of the most significant human pathogens, is a Gram-positive, alpha-hemolytic bacterium of the genus Streptococcus. Since being discovered in 1881, it is considered to be a major cause of pneumonia and thus the subject of much humoral immunity research. The genome of S. pneumoniae is a closed, circular DNA structure, with a core set of 1553 genes, 154 genes in its virulome, and 176 genes to maintain a noninvasive phenotype. In fact, S. pneumoniae is part of the normal upper respiratory tract flora, but become pathogenic under the right conditions, usually when the immune system of the host is suppressed. It is the main cause of community-acquired pneumonia and meningitis in the elderly and children. S. pneumoniae related diseases include pneumonia, pneumococcal meningitis, and sepsis. Several vaccines against S. pneumoniae have been developed to protect against invasive infection.
3. Research Details
Studies have shown that the combination of the new influenza A virus vaccine (based on inactivated whole influenza virus) and the new pneumococcal vaccine can induce and enhance cross-protective immunity against different influenza virus strains, which are published in the journal Nature Microbiology.
The study confirmed that the enhancement of immunity is related to the direct physical interaction between viruses and bacteria. The latest study, led by Dr. Mohammed Alsharifi and Professor James Paton, builds on previous studies to develop a new inactivated vaccine that targets the components of viruses and bacteria that do not differ from strain to strain.
The current flu vaccine is aimed at surface molecules affected by mutations, so it needs to be updated annually to match the emerging virus. Existing pneumococcal vaccines provide more lasting protection, but only cover a small number of pathogenic strains. The researchers say there is also a need for better vaccines to provide broad-spectrum protection.
Dr. Alsharifi said: “Influenza infection makes patients vulnerable to severe pneumococcal pneumonia and the mortality rate is very high. Although current vaccines have this well-known synergy, vaccination strategies target individual pathogens. We are working on ways to combine our new influenza vaccine with pneumococcal vaccine into a single vaccine and have shown a very significant increase in the immune response to different subtypes of influenza. “
Previous studies published by the research team have shown that their pneumococcal vaccines are similarly more effective when vaccinated in conjunction with influenza vaccines, resulting in a two-way enhancement of pathogen-specific immunity. Some biological companies are currently commercializing the new vaccine.