In all likelihood, the ~14-kDa region may have other protein fragment(s) that went unnoticed with Coomassie Blue staining of the gel. This assumption is supported by results of Western blot of fractionated ES–H.c-C3BP with the antiserum raised against the ~14-kDa band where an additional band of ~20 kDa was also stained by the antibody. In some blots, a faint band in the 37-kDa region was also seen, but it faded after membrane drying. The monomeric form of GAPDH can associate to form multimers [22]. Thus, the cross-reacting high molecular bands observed in the Western blot of adult parasite extract with anti-H.c-C3BP antiserum may be multimers of GAPDH,

which degraded on storage to lower-size polypeptides. The susceptibility

of GAPDH to hydrolysis is further supported by DAPT its degradation during storage with the generation of multiple fragments including the ~14-kDa band. The hydrolysis of GAPDH in the ES products may be facilitated by the parasite proteases that are secreted [23]. Proteome analysis of H. contortus ES products suggested presence of five glycolytic enzymes [21]; GAPDH may be one of these. The fact that the antibodies against GAPDH were present in the sera of the infected animals suggests that the enzyme was secreted by the parasite and recognized Inhibitor Library by the host immune effector cells. The strong evidences suggesting 14-kDa H.c-C3BP as GAPDH representative were further supported by other facts. The recombinant H. contortus GAPDH also bound to C3 protein and inhibited complement-mediated lysis of sensitized erythrocytes. Also, the presence of parasite GAPDH inhibited MAC formation. Pathogens have devised different ways to evade the host immune system. Innate

immune system is the first line of defence against the pathogens including parasites. This system exerts significant evolutionary pressure on pathogens, which have developed protective mechanisms [24-26]. Complement system, which includes a series of proteins, is an arm of the innate defence system. In recent Mannose-binding protein-associated serine protease years, multiple complement evasion strategies have been identified in pathogens. Staphylococcus aureus, a Gram-negative bacteria, that infects human and animals has multiple complement-inhibitory proteins. This bacterium secretes a complement-inhibitory protein (SCIN) that affects C3 convertase function [27]. Two other complement-modulatory proteins of S. aureus are as follows: extracellular fibrinogen-binding protein (Efb) that binds to C3 and inhibits complement activation and EhpA, a homologue of Efb, with a size of ~10 kDa is also secreted by S. aureus and inhibits alternate complement pathway by altering the complement C3 conformation [28]. Streptococci have a surface protein that is also secreted; this protein binds to complement C5a. C5a is known to activate neutrophils which release H2O2 that is lethal.