Mouse Anti-S. pneumoniae CPS 33F Monoclonal antibody, clone 1264

Streptococcus pneumoniae is a gram-positive bacterium with spear-shaped bodies arranged in pairs or short chains. Toxic strains have a capsule with a chemical composition of polysaccharides outside the bacteria. 5%~10% of normal people carry these bacteria in their upper respiratory tract. Toxic strains are important pathogens causing human diseases. Among pyogenic cocci, the pathogenicity of Streptococcus pneumoniae is second only to that of Staphylococcus aureus. The difference is that Streptococcus pneumoniae rarely develops resistance to penicillin antibiotics. The main virulence factors of Streptococcus pneumoniae are pneumolysin and the capsule. The capsule is antigenic and is the basis for the typing of Streptococcus pneumoniae. This bacterium can cause lobar pneumonia, meningitis, bronchitis and other diseases. Pneumococcal pneumonia often develops suddenly, with symptoms of high fever, chills, severe pleural pain, and coughing up rusty sputum. 10% to 20% of patients may have bacteremia during the high fever period. Its pathological manifestations are mainly a large amount of fibrin exudate in the alveoli at first, followed by the infiltration of red blood cells and white blood cells into the alveoli, which eventually leads to consolidation of lung tissue in the affected area. The lesions usually only affect a single lobe, so it is called lobar pneumonia. If antibiotics are used in the early stage of treatment, pulmonary consolidation can be prevented.

Figure 1. Schematic organization of the pneumococcal CPS machinery and BY-kinase. (Sources: Nourikyan J, et al. 2015)

Typical Streptococcus pneumoniae is a Gram-positive coccus with a diameter of about 1μm. It is often arranged in pairs. The bacteria are spear-shaped, with the wide ends facing each other and the tips pointing outward. In sputum and pus specimens, they may appear as a single or short chain. Virulent strains form capsules in the body. The capsule does not stain during ordinary staining, and appears as a transparent ring around the bacteria. There are no flagella and spores. When the bacteria are old, or after the bacteria are lysed by the production of autolysin, they may appear Gram-negative. This bacterium has high nutritional requirements and needs to grow in a culture medium containing blood or serum. Small round, raised, smooth and moist colonies are formed on solid culture media. In the early stage of culture, the colonies are raised in a dome shape. As the culture time increases, the autolysin produced by the bacteria lyses the bacteria, causing the center of the colony to be concave and the edges to be raised into a "umbilical shape". Surfactants such as bile or deoxycholate can activate autolysin and accelerate bacterial autolysis. They are facultative anaerobic, CO₂ 5-10% grows best, and the resulting colonies are surrounded by grass-green hemolytic rings. If cultured in liquid culture medium for 24 hours, it is uniformly turbid, and can become clear later due to autolysis. Alpha-hemolytic streptococci do not produce autolytic enzymes, so they cannot be dissolved by adding surfactants such as bile salts. This feature can be used to distinguish between alpha-hemolytic streptococci and pneumococci. Pneumococci form alpha-hemolytic rings around colonies on blood agar plates. The energy for bacterial growth comes from the decomposition of glucose, accompanied by the formation of lactic acid. The accumulation of lactic acid inhibits bacterial growth, so intermittent addition of alkali can cause pneumococci to multiply in large numbers. The bacteria can decompose a variety of sugars, producing acid but not gas. Most newly isolated pneumococci can ferment inulin, so the inulin fermentation test has a certain reference value in distinguishing pneumococci from alpha-hemolytic streptococci.

The surface of Streptococcus pneumoniae is covered with a capsule composed of polysaccharides. It is a key virulence factor and an important antigen that prevents Streptococcus pneumoniae from being phagocytized by host immune cells, and is also the basis for bacterial typing. In this species, capsular polysaccharides exhibit enormous structural diversity, resulting in significant differences in immunogenicity and antigenicity. Studies have shown that the capsular polysaccharide of highly virulent pneumococcal serotypes has been made into sugar vaccines and has a major role to play in preventing infection. Vaccination is therefore an effective specific preventive measure with an extremely high health economic value. Pneumococcal vaccine is a vaccine against pneumococcal diseases, which is mainly divided into two types: pneumococcal conjugate vaccine (PCV) and pneumococcal polysaccharide vaccine (PPV). To date, more than 90 different capsular serotypes have been identified, each of which can be distinguished by serological reactions, has variations in chemical structure and is associated with its genetic mutations. These unique differences may be associated with different epidemiological characteristics, including changes in the spread and prevalence of the disease. For example, capsules with a higher charge-to-carbon ratio may be larger, making them more resistant to neutrophil clearance. Based on differences in the capsular polysaccharide antigens on the surface of Streptococcus pneumoniae, Streptococcus pneumoniae can be classified into 46 serogroups and 93 serotypes. Serogroups are named numerically, e.g. group 6, and if there are several serotypes in the group, letters are added to distinguish them, e.g. 6A-6D. The survival and pathogenicity of Streptococcus pneumoniae of different capsular serotypes also differ. Pneumococcal capsular polysaccharide (PCPS) serotype 33F is one of these.

Pneumococcal Capsular Polysaccharide
S. pneumoniae Capsule
Pneumococcal Polysaccharide
Pneumococcus CPS
Capsule Polysaccharide of S. pneumoniae
Pneumococcal Capsule Polysaccharide Antigen
S. pneumoniae Capsular Antigen