Trichinella spiralis: Intranasal immunization with attenuated Salmonella enterica Carrying a gp43 antigen-derived 30mer epitope elicits protection in BALB/c mice E.N. Pompa-Mera a,b , L. Yépez-Mulia b , A. Ocaña-Mondragón a , E.A. García-Zepeda c , G. Ortega-Pierres d , C.R. González-Bonilla a,⇑ a Unidad de Investigación Médica en Inmunología e Infectología, Hospital de Infectología, Centro Médico Nacional La Raza, IMSS, Mexico City, Mexico b Unidad de Investigación en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, IMSS, Mexico City, Mexico c Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico d Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados-Instituto Politécnico Nacional, Mexico City, Mexico article info Article history: Received 27 June 2008 Received in revised form 26 July 2011 Accepted 16 August 2011 Available online 31 August 2011 Keywords: Trichinella spiralis gp43 Antigen Attenuated Salmonella Vaccines ShdA Autotransporters abstract Trichinellosis is a public health problem and is considered an emergent/re-emergent disease in various countries. The etiological agent of trichinellosis is the nematode Trichinella, which infects domestic ani- mals such as pigs and horses, as well as wild animals and humans. A veterinary vaccine could be an option to control the disease in domestic animals. Although several vaccine candidates have shown promising results, a vaccine against trichinellosis remains unavailable to date. Attenuated Salmonella strains are especially attractive live vectors because they elicit mucosal immunity, which is known to be important for the control of Trichinella spiralis infection at the intestinal level and can be administered by oral or intranasal routes. In this study, the autotransporter ShdA was used to display, on the surface of the Salmonella enterica serovar Typhimurium SL3261, the 210–239 amino acid epitope, (designated as Ag30) derived from the 43 kDa glycoprotein of T. spiralis muscle larvae. The fusion protein elicited anti- bodies in BALB/c mice that were able to recognize the native epitope on the surface of T. spiralis muscle larvae. Mice immunized by intranasal route with the recombinant Salmonella induced a protective immune response against the T. spiralis challenge, reducing by 61.83% the adult burden at day eight post- infection. This immune response was characterized by the induction of antigen-specific IgG1 and of IL-5 production. This study demonstrates the usefulness of Salmonella as a carrier of nematode epitopes pro- viding a surface display system for intestinal parasite vaccine applications. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction Trichinellosis is caused by nematodes of the genus Trichinella, which are widespread throughout the world and infect many ani- mal species, including humans (Gajadhar and Gamble, 2000). Hu- man trichinellosis has been documented to date in 55 countries (27.8%) worldwide, including industrialized and non-industrialized countries (Pozio, 2007) and is considered as an emergent/reemer- gent disease (Dupouy-Camet, 2000; Gajadhar and Gamble, 2000; Murrell and Pozio, 2000). The global prevalence of trichinellosis is unknown, but it is estimated that ca. 11 million people may be infected with the parasite. Trichinellosis is mainly acquired by ingestion of the meat of domestic animals such as pigs and horses; however, several outbreaks have been caused by the ingestion of the meat of wild animals especially wild boar and bears (Gamito- Santos et al., 2009; Ribicich et al., 2010; Cui et al., 2011) Trichinella spiralis, the main species affecting humans, is acquired by ingestion of meat containing viable infective larvae enclosed in a structure called the ‘‘nurse cell’’. Gastric fluid allows the release of muscle larvae (ML) from nurse cells and once released, the parasites develop into adults in the duodenum and jejunum. The adult worms mate and the fe- males produce large numbers of newborn larvae, which penetrate the intestinal wall, enter the lymphatic system, and travel through the bloodstream into striated muscle. Once the parasites reach this tissue, the larvae develop into ML and induce the transformation of muscle cells to the nurse-cell complex, which eventually calcifies. The clinical features of trichinellosis vary from mild to severe dis- ease depending on parasite numbers, their localization, and the intensity of the inflammatory reaction. Fever, myalgia, and persis- tent fatigue are the most common symptoms, which often associ- ated with marked eosinophilia. The disease often causes neurologic and cardiac dysfunction due to the arteriolar microthrombi that lead to cerebral and myocardial infarction. 0014-4894/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.exppara.2011.08.013 ⇑ Corresponding author. Address: Unidad de Investigación Médica en Inmunolo- gía e Infectología, Hospital de Infectología, Centro Médico Nacional La Raza, IMSS, Vallejo esq. Seris sn, Col. La Raza, 02200 Mexico, D.F., Mexico. E-mail addresses: crgb@prodigy.net.mx, cesar.gonzalezb@imss.gob.mx (C.R. González-Bonilla). Experimental Parasitology 129 (2011) 393–401 Contents lists available at SciVerse ScienceDirect Experimental Parasitology journal homepage: www.elsevier.com/locate/yexpr