Pneumococcal choline-binding protein A (PcpA) (PcpA)

Pneumococcal choline-binding protein A (PcpA) is a surface-exposed adhesin of Streptococcus pneumoniae that plays a vital role in the early stages of infection and bacterial colonization [6, 14]. As a member of the choline-binding protein family, it attaches non-covalently to the phosphorylcholine moieties of the bacterial cell wall through its C-terminal choline-binding domain [14, 16]. PcpA is structurally characterized by its N-terminal leucine-rich repeats (LRR), which facilitate high-affinity binding to host lung epithelial cells, aiding in both asymptomatic nasopharyngeal carriage and the progression to invasive disease [14, 17]. A unique feature of PcpA is its manganese-dependent regulation; it is transcriptionally repressed by the PsaR protein in the presence of high manganese concentrations, leading to maximal expression in the relatively low-manganese environments of the human respiratory tract and blood [14, 21]. PcpA is a prominent target for next-generation protein-based vaccines due to its high conservation across diverse pneumococcal serotypes [2, 14]. Investigational vaccines, such as those combining PcpA with other protein antigens like PhtD, are designed to elicit opsonophagocytic antibodies that block adhesion and promote immune-mediated clearance, potentially overcoming the serotype-coverage limitations of current polysaccharide vaccines [2, 8, 14].

Other names

PcpASP_2108

Vaccine-mediated induction of opsonophagocytic and neutralizing antibodies that inhibit bacterial adherence to host cells and facilitate pathogen clearance