Vaccination of lambs against Haemonchus contortus infection with a somatic protein (Hc23) from adult helminths Elshaima M. Fawzi, María Elena González-Sánchez, María Jesús Corral, Montserrat Cuquerella, José M. Alunda ⇑ Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, 28040 Madrid, Spain article info Article history: Received 11 December 2013 Received in revised form 26 February 2014 Accepted 27 February 2014 Available online xxxx Keywords: Hc23 Haemonchus contortus Vaccination Lambs Native protein Immunochromatography Haemonchosis abstract A somatic protein from adult Haemonchus contortus (Hc23), the most abundant component in a low molecular weight fraction with known immunizing effect against experimental haemonchosis, has been purified by immunochromatography. The immunoprophylactic value of Hc23 was tested in groups of 5– 6 months old Assaf lambs using Al(OH) 3 or Escherichia coli lipopolysaccharide + inactivated Propionibac- terium acnes as adjuvant and the results compared with uninfected control, uninfected and challenged or infected and challenged lambs. Immunization with Hc23 in either adjuvant elicited significant reduc- tions in fecal egg counts after challenge with 15,000 L3s (70.67%–85.64%, respectively) and reduced (67.1% and 86%) abomasal worm counts (45 days post-challenge). Immunized lambs displayed higher peripheral eosinophil counts, were less anaemic and had weight gains than challenged controls. The results suggest that the Hc23 antigen can induce a partially protective response against haemonchosis in lambs. Ó 2014 Published by Elsevier Ltd. on behalf of Australian Society for Parasitology Inc. 1. Introduction The abomasal nematode Haemonchus contortus is a highly path- ogenic blood feeding parasite of small ruminants, especially lambs. The L4 and adult stages of the parasite attach to the abomasal mucosa of the host, resulting in anemia which can be severe enough to cause death. Haemonchus contortus infections have a wide range of clinical courses from acute, often fatal, especially for young lambs, to chronic forms, particularly in older lambs and sheep. Mortality ranging from 30–50% has been reported in lambs and kids in acute cases (Aumont et al., 1997; Baker, 1997). Production losses in the chronic subclinical infection include weight loss, reduced weight gain, reproductive inefficiency (decreased fertility), reduction of wool growth and quality, and decline in the milk yield. Globally, haemonchosis is by far the most important nematode infection of small ruminants (Waller and Chandrawathani, 2005) and represents 15% of all gastrointestinal diseases of these species worldwide (http://www.fao.org). Control of the infection relies mainly on the use of anthelmintic drugs, although high levels of anthelmintic resistance (AR) have been described in the major parasites affecting ruminants (Echevarria et al., 1996; Waller, 1997; Kaplan, 2004). The appearance of AR has become a common phenomenon, including multiple drug resistance against the three major classes of anthelmintic drugs (benzimidazoles, imidothiazoles and macrocyclic lactones) that compromise successful chemotherapy (Jackson and Coop, 2000; Kaminsky, 2003; Coles et al., 2006; Wrigley et al., 2006). Among possible alternative strategies to control H. contortus, vaccine development is the most investigated method (Miller and Horohov, 2006). To date no commercial vaccines are available for any gastro-intestinal nematode (GIN). Several types of proteins have been used to immunize lambs or kid goats against GIN, using both hidden and exposed antigens (Ags). Hidden Ags are mainly enzymes from the gut of the parasite and are not recognized during infection. Vaccination induces high levels of antibodies (Abs) which probably neutralize these enzymes. Natural Ags are recog- nized during the infection and include excretory/secretory (ES), surface and somatic Ags and can be effective against both blood and non-blood feeding nematodes (Newton and Meeusen, 2003). An advantage of the so-called natural antigens is the possibility of natural boosting whilst being continuously infected on pasture. Variable results have been obtained in vaccination trials with Haemonchus contortus but some Ags have achieved notable protec- tion levels. Thus Schallig and van Leeuwen (1997) found protection between 75% and 85% with an enriched fraction of ES Ags contain- ing two proteins (15 and 24 KDa). Newton and Munn (1999) http://dx.doi.org/10.1016/j.ijpara.2014.02.009 0020-7519/Ó 2014 Published by Elsevier Ltd. on behalf of Australian Society for Parasitology Inc. ⇑ Corresponding author. Tel.: +34 913943701; fax: +34 913943908. E-mail address: jmalunda@ucm.es (J.M. Alunda). International Journal for Parasitology xxx (2014) xxx–xxx Contents lists available at ScienceDirect International Journal for Parasitology journal homepage: www.elsevier.com/locate/ijpara Please cite this article in press as: Fawzi, E.M., et al. Vaccination of lambs against Haemonchus contortus infection with a somatic protein (Hc23) from adult helminths. Int. J. Parasitol. (2014), http://dx.doi.org/10.1016/j.ijpara.2014.02.009