No protection in chickens immunized by the oral or intra-muscular immunization route with Ascaridia galli soluble antigen.

In chickens, the nematode Ascaridia galli is found with prevalences of up to 100% causing economic losses to farmers. No avian nematode vaccines have yet been developed and detailed knowledge about the chicken immune response towards A. galli is therefore of great importance. The objective of this study was to evaluate the induction of protective immune responses to A. galli soluble antigen by different immunization routes. Chickens were immunized with a crude extract of A. galli via an oral or intra-muscular route using cholera toxin B subunit as adjuvant and subsequently challenged with A. galli. Only chickens immunized via the intra-muscular route developed a specific A. galli antibody response. Frequencies of γδ T cells in spleen were higher 7 days after the first immunization in both groups but only significantly so in the intra-muscularly immunized group. In addition, systemic immunization had an effect on both Th1 and Th2 cytokines in caecal tonsils and Meckel's diverticulum. Thus both humoral and cellular immune responses are inducible by soluble A. galli antigen, but in this study no protection against the parasite was achieved.

Comparison of parasite-specific immunoglobulin levels in two chicken lines during sustained infection with Ascaridia galli.

Increasingly large numbers of poultry are held in production systems with access to outdoor areas. In these systems intestinal helminths are found with flock prevalences of up to 100%. Helminth infections influence chicken health negatively, which is why the following investigation has been performed. In the present experiment, 20 chickens of two inbred chicken lines containing the major histocompatibility complex (MHC) haplotypes, B14 and R5, were inoculated with 500 embryonated Ascaridia galli eggs. The A. galli-specific IgG titres of serum samples and the excretion of A. galli eggs in chicken faeces were measured for a period of 81 weeks. The level of excreted A. galli eggs measured as eggs per gram chicken faeces (EPG) varied greatly between chickens in each line. Significant differences were found between the two lines and with the R5 chickens reaching the highest levels. Likewise, the A. galli-specific IgG titres in serum differed significantly between the two lines, and an inverse relationship between infection level (EPG) and antibody titres was found. Although this inverse relationship suggests that humoral immunity may be involved in protection against A. galli infection, the high antibody titres did not prevent continued infection.

Molecular and functional characterization of mouse S5D-SRCRB: a new group B member of the scavenger receptor cysteine-rich superfamily.

The scavenger receptor cysteine-rich superfamily (SRCR-SF) members are transmembrane and/or secreted receptors exhibiting one or several repeats of a cysteine-rich protein module of ∼100 aa, named scavenger receptor cysteine-rich (SRCR). Two types of SRCR domains (A or B) have been reported, which differ in the number of coding exons and intradomain cysteines. Although no unifying function has been reported for SRCR-SF members, recognition of pathogen-associated molecular patterns (PAMPs) was recently shown for some of them. In this article, we report the structural and functional characterization of mouse S5D-SRCRB, a new group B member of the SRCR-SF. The s5d-srcrb gene maps at mouse chromosome 7 and encompasses 14 exons extending over 15 kb. The longest cDNA sequence found is 4286 bp in length and encodes a mature protein of 1371 aa, with a predicted M(r) of 144.6 kDa. Using an episomal mammalian-expression system, a glycosylated soluble recombinant form >200 kDa was obtained and used as immunogen for the generation of specific rat mAbs. Subsequent immunohistochemical and real-time PCR analysis showed significant S5D-SRCRB expression in murine genitourinary and digestive tracts. S5D-SRCRB was shown to bind endogenous extracellular matrix proteins (laminin and galectin-1), as well as PAMPs present on Gram-positive and Gram-negative bacteria and fungi. PAMP binding by S5D-SRCRB induced microbial aggregation and subsequent inhibition of PAMP-induced cytokine release. These abilities suggest that S5D-SRCRB might play a role in the innate defense and homeostasis of certain specialized epithelial surfaces.