PNEUMOCOCCAL CHOLINE-BINDING PROTEIN A
Gene Name - PcpA
Cell Location - Cell wall - Pneumococcal choline-binding protein A is bound to the cell wall via phosphoryl-choline moiety [1].
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FUNCTION
PcpA plays a role in the protection against sepsis and lung infections [1]. Its expression in cells only occurs in places of low manganese concentrations, such as the lungs and blood, and areas of high concentrations lead to limited PcpA expression. Therefore, its expression is largely controlled by manganese-dependant regulators [2].
It also functions as an adhesin, whereby it aids in the adherence of Streptococcus pneumoniae to epithelial cells found in the nasopharynx and lungs [3].
STRUCTURE
Click on the image for more information on the secondary and tertiary structure of pneumococcal choline-binding protein A.
PROTEIN SEQUENCE
10 20 30 40 50
MKKTTILSLT TAAVILAAYV PNEPILADTP SSEVIKETKV GSIIQQNNIK
60 70 80 90 100
YKVLTVEGNI GTVQVGNGVT PVEFEAGQDG KPFTIPTKIT VGDKVFTVTE
110 120 130 140 150
VASQAFSYYP DETGRIVYYP SSITIPSSIK KIQKKGFHGS KAKTIIFDKG
160 170 180 190 200
SQLEKIEDRA FDFSELEEIE LPASLEYIGT SAFSFSQKLK KLTFSSSSKL
210 220 230 240 250
ELISHEAFAN LSNLEKLTLP KSVKTLGSNL FRLTTSLKHV DVEEGNESFA
260 270 280 290 300
SVDGVLFSKD KTQLIYYPSQ KNDESYKTPK ETKELASYSF NKNSYLKKLE
310 320 330 340 350
LNEGLEKIGT FAFADAIKLE EISLPNSLET IERLAFYGNL ELKELILPDN
360 370 380 390 400
VKNFGKHVMN GLPKLKSLTI GNNINSLPSF FLSGVLDSLK EIHIKNKSTE
410 420 430 440 450
FSVKKDTFAI PETVKFYVTS EHIKDVLKSN LSTSNDIIVE KVDNIKQETD
460 470 480 490 500
VAKPKKNSNQ GVVGWVKDKG LWYYLNESGS MATGWVKDKG LWYYLNESGS
510 520 530 540 550
MATGWVKDKG LWYYLNESGS MATGWVKDKG LWYYLNESGS MATGWVKDKG
560 570 580 590 600
LWYYLNESGS MATGWVKDKG LWYYLNESGS MATGWVTVSG KWYYTYNSGD
610 620
LLVNTTTPDG YRVNANGEWV G
SEQUENCE LENGTH - 621
CURRENT FIELD STATUS

CURRENT TRIAL STATUS
Phase 1
-
Clinical trials of a PcpA vaccine [1].
-
Clinical trials of a PcpA vaccine combined with PhtD [1][4].
-
Immunisation with PcpA in murine model [2].
-
Immunisation of toddlers with PcpA PhtD, and PlyD1 [4].

IMMUNE RESPONSE GENERATED
-
PcpA has shown high levels of protection in preclinical studies against pneumonia and sepsis.
-
Mice immunised with PcpA through a sepsis and pneumonia models showed significantly lower levels of Streptococcus pneumonia cells and infection in their lungs than control mice. Immunisation also led to higher survival times in mice.
-
PcpA failed to show signs of protecting against colonisation and carriage [2].

MECHANISM OF VIRULENCE
-
Choline-binding protein which plays relevant physiological role in virulence [1].
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