Table 2.

The most studied proteins regarding the identification of the antigenic regions they contain.

Protein Name	Function	Virulence Factor	Location	3-D structure of the Full Length Proteins
Pneumococcal surface protein A (PspA)	Cellular Metabolism and Immune Evasion	Choline-Binding Proteins (CBPs)	Bound to the cell wall via PCho moiety
Pneumococcal Choline-Binding Protein A (PcpA)	Protection Against Lung Infection and Sepsis	Choline-Binding Proteins (CBPs)	Bound to the cell wall via PCho moiety
Secreted 45-KDa Protein, Usp45-Hydrolase (PcsB)	Virulence	Non-Classical Surface-Exposed Proteins	Membrane
Serine/Threonine Protein Kinase (StkP)	Cellular Metabolism and Fitness	Non-Classical Surface-Exposed Proteins	Membrane
Peptide Permease Enzyme, Manganese ABC Transporter (PsaA)	Immune Evasion	Lipoproteins	Surface of the cell wall
Pneumolysin D (PlyD)	Cytolytic Toxin, Adherence, Immune Evasion, Invasion, Dissemination and Complement Activation	Non-Classical Surface-Exposed Proteins	Cytoplasmic toxin
Pneumolysin toxoid (dPly)	Toxoid	Non-Classical Surface-Exposed Proteins	Toxoid	N.A. *
Choline-binding protein D (CbpD)	Colonization	Choline-Binding Proteins (CBPs)	Bound to the cell wall via PCho moiety
Histidine triad protein D (PhtD)	Adherence and Immune Evasion	Lipoproteins	Surface of the cell wall
Histidine triad protein E (PhtE)	Adherence and Immune Evasion	Lipoproteins	Surface of the cell wall
Histidine triad protein A (PhtA)	Adherence and Immune Evasion	Lipoproteins	Surface of the cell wall	N.A. *
Histidine triad protein B (PhtB)	Adherence and Immune Evasion	Lipoproteins	Surface of the cell wall	N.A. *
Plasmin and Fibronectin-Binding Protein A (PfbB)	Adherence, Immune Evasion and Antiphagocytosis	LPxTG—Proteins	Anchored to well wall by the enzyme sortase A
Zinc metalloproteinase B (ZmpB)	Immune Evasion and Colonization	LPxTG—Proteins	Anchored to well wall by the enzyme sortase A

* The 3-D structure of the corresponding protein has not been defined yet.