Protective immunity to the blood-feeding nematode Haemonchus contortus induced by vaccination with parasite low molecular weight antigens

Abstract

Partially purified low molecular weight antigens obtained by gel filtration of whole worm homogenates or total adult excretory-secretory (ES) products were tested in a vaccination experiment to determine their ability to induce protective immunity against Haemonchus contortus in sheep. Sheep were challenged with 20,000 infective 3rd-stage larvae. One animal in the low molecular weight vaccinated group showed no protection against H. contortus, whereas the 4 other sheep in this group showed a mean reduction of 99.9% in faecal egg counts and of 97.6% in abomasal worm burden compared to the non-vaccinated controls and the adjuvant controls. The ES-vaccinated sheep showed a 32.2% reduction in parasite egg production and a 63.7% reduction in abomasal worm counts. Analysis of the humoral immune responses revealed no significant differences in antibody recognition of putative protective antigens between the protected and non-protected vaccinated animals. However, a marked lower lymphocyte proliferation response was found in non-protected sheep.

Kinetics of antibody response by Dot-ELISA in rabbits immunized with adultHaemonchus contortusantigen

“…Similar results were obtained in random-bred sheep immunized with H-gal-GP (Haemonchus galactose containing glycoprotein) complex (Smith et al. 1999) and in vaccination studies with E/S antigens of adult H. contortus oi MW 15 and 24kDa (Schallig & Leeuwen, 1997). This is most likely to be caused by genetically determined variation in the ability of individuals to respond to parasites (Dineen et ai, 1978;Gray, 1987).…”

“…150 and 180 days (Table I) which may be due to secondary immune response stimulated by booster immunizations. A constant increase in antibody level against H. contortus excretory/secretory (E/S) antigens was observed in sheep, from two weeks after first injection and each subsequent vaccine injection boosted humoral immune response (Schallig & Leeuwen, 1997). Even serum antibody response of Texel sheep experimentally infected with larvae suggested an immunological memory for H. contortus larval antigens (Schallig et al, 1994).…”

Isolation and immunolocalization of a putative protective antigen (p26/23) from adult Haemonchus contortus

“…The partial sequencing of the isolated protein revealed a 100% identity with the N terminus of one of the peptides described by Domínguez-Toraño et al (2000). The MW of the peptide p26/23, of approximately 24 kDa, does not correspond with any immunoprotective antigen utilized to develop vaccines against haemonchosis to date except for the ES antigen of 24 kDa (ES24) previously described by Schallig and Van Leeuwen (1997). As our candidate, ES24 peptide is also expressed at the different stages of nematode development analyzed (L3 and adults).…”

“…Under these conditions, immunoprophylaxis could constitute an attractive alternative (Vercruysse et al 2007). A number of potentially protective antigens, both "natural" (NAGS)-exposed to the host immune system during the natural infection-and "hidden" (HAGS)-unexposed-have been identified and used in vaccination trials (Boisvenue et al 1992;Munn et al 1993a,b;Schallig and Van Leeuwen 1997;Schallig et al 1977b;Knox et al 1999;Newton and Meeusen 2003). Most studies have focused on hidden antigens because they are not exposed to the host's immune system and, therefore, would be less susceptible to selection pressure (Munn 1997).…”

Gender-enriched transcription of activation associated secreted proteins in Ostertagia ostertagi

“…Activation associated secreted proteins (ASPs) have been described in a wide variety of parasitic nematodes such as Ancylostoma caninum (Hawdon et al, 1996Bin et al, 2003), Ancylostoma duodenale (Bin et al, 1999),Ancylostoma ceylanicum (Goud et al, 2004), Necator americanus (Bin et al, 1999;Daub et al, 2000;Asojo et al, 2005), Onchocerca volvulus (Tawe et al, 2000), Brugia malayi (Murray et al, 2001), Haemonchus contortus (Schallig and Van Leeuwen, 1997;Schallig et al, 1997a,b;Rehman and Jasmer, 1998), Cooperia punctata (Yatsuda et al, 2002) and Ostertagia ostertagi . They are of general interest as they have shown their protective capacity in multiple vaccination trials against Ancylostoma spp., H. contortus and O. ostertagi (Schallig et al, 1997a;Ghosh and Hotez, 1999;Geldhof et al, 2002Geldhof et al, , 2004Goud et al, 2004;Meyvis et al, 2007).…”