Adjuvant effect of LPS and killed Propionibacterium acnes on the development of experimental gastrointestinal nematode infestation in sheep L. C. J. ABEL, 1 S. CHEN, 1 L. G. RICCA, 1 M. F. MARTINS, 1 M. GARCIA, 1 R. Z. ANANIAS, 2 J. S. MUSSALEM, 2 C. C. SQUAIELLA, 2 R. J. SHAW 3 & I. M. LONGO-MAUGÉRI 2 1 Veterinary Medicine, Universidade Paulista, UNIP, S¼o Paulo, Brasil, 2 Division of Immunology, Universidade Federal de S¼o Paulo, UNIFESP, S¼o Paulo, Brasil, 3 Hopkirk Research Institute, AgResearch Grasslands Research Centre, Palmerston North, New Zealand SUMMARY Gastrointestinal helminthic infection is an important world- wide sheep disease. The emergence of anthelminthic resistance has led to drives to seek new means of therapeutic control of helminthiasis in sheep. Several data demonstrated the adjuvant effect of Propionibacterium acnes on resistance to infection. Herein, we evaluate the adjuvant effect of the commercial suspension containing LPS and P. acnes on experimental helminthiasis. Sheep received three doses of LPS and P. acnes commercial suspension or saline 0Æ9% (control group). Both groups received orally Haemonchus contortus infective larvae on day 0. Parasitological, haematological, lymphoproliferation analysis, IL-5 and IgE determination were made once a week until 35th day after infection. Our results revealed increase on packed cell volumes on day 14, in LPS + P. acnes treated group. On 21st and 35th days after infection in the same group occurred increase on circu- lating eosinophils and lymphocytes, and also in the lympho- proliferative response to mitogen. On 35th day, the faecal eggs peak in LPS + P. acnes treated group was significantly lower than control. A negative correlation between faecal eggs counts and circulating eosinophils in the immunostimu- lant treated group was also observed. Our findings suggest that LPS + P. acnes suspension can be used as a strategy to control helminthiasis in sheep. Keywords helminthiasis, immunostimulant, lymphocytes, sheep INTRODUCTION Among the difficulties that affect sheep breeding, gastro- intestinal helminthiasis is of primary concern. Worm infes- tations cause economic damages in farms raising small ruminants due to losses in the production of milk, meat, wool, in body weight and in the carcass quality of slaugh- tered animals (1,2). Generally, the control of gastrointestinal nematodes depends on the repeated use of anthelmintics, but the inadequate and injudicious animal treatment has led to the appearance of resistance worms (3). Efforts to curb production losses caused by sheep nematode infestation have led to the development of control methods to complement or replace anthelmintics (4). Factors changing immune response such as environment conditions, nutritional deficiencies and handling favoured the parasitic disease (5,6). There is evidence that at least part of the natural variation in resistance to nematode infections is under genetic control, and in the Haemonchus contortus infection it is mediated by immunological mech- anisms (7–10). In an experimental model, selected resistant Merino sheep, when infected with H. contortus, showed that, for both abomasal and mesenteric lymph node lymphocytes, IFN-c production was decreased and IL-5 was increased when compared to the nonselected line at 5th and 28th days post-infection (9). Terefe et al. (11) suggested that the protector immune response to H. contortus infection is Th2 pattern, once a persistent and elevated Th2 cytokine mRNA transcription and blood eosinophilia were detected in resistant Barbados Black Belly lambs. The immune response role in helminthiasis was also demonstrated by Garcia et al. (12), that demonstrated more severe helmin- thiasis development when previously induced immuno- ssupression in sheep using cyclophosphamide. Correspondence: Lucia Jamli Abel, Rua Francisco JosØ da Silva, 67 ⁄ 131, 05726-100, S¼o Paulo, SP, Brasil (e-mail: luciaabel@uol. com.br). Disclosures: The authors declare there are not conflicts of interest including all relevant financial interests. Received: 2 October 2008 Accepted for publication: 08 May 2009 Parasite Immunology, 2009, 31, 604–612 DOI: 10.1111/j.1365-3024.2009.01132.x 604 Ó 2009 Blackwell Publishing Ltd