After the immunizing infection, the key experimental immunized-challenged group was rested for 4 weeks to enable the mucosa to recover, before being challenged with a low-dose secondary infection. Our hypothesis is that challenged animals should respond with a considerably more vigorous intestinal inflammatory response than that evident during primary exposure, and to enable this
to be quantified accurately against baseline values of each of the parameters that we measured, we included four carefully chosen control groups. The strain of A. ceylanicum used was that maintained at the University of Nottingham since 1984, originally acquired from Dr. Rajasekariah of Hindustan CIBA-Geigy Ltd., Bombay, India. It is believed to be of dog origin. The methods employed for maintenance of the parasite, for worm recovery and faecal egg counts have all been described previously in full (16,19). Worms were Dabrafenib chemical structure removed from infected animals by treatment with ivermectin (‘Ivomec super’ MSD AGVET, Division of Merk Sharp and Dohme Limited, Holland). A stock concentration of 200 μg/mL drug was made by a 1 in 50 dilution using distilled water and this was used to treat at 200 μg/kg body weight. The Golden hamsters (DSN strain) used in this study were originally obtained from Harlan Olac in 1983 and since then maintained
in the animal house of the School of Biology as a closed colony. Only female hamsters were used
in this experiment. Animals were kept under conventional animal house conditions. Pelleted food and tap water were supplied learn more ad libitum. Cages were cleaned twice a week to prevent re-infection. Animals were first weighed 1 or 2 weeks before infection and thereafter twice a week until the completion of each experiment. As the colony was maintained under conventional animal house conditions, the animals were exposed to various micro-organisms present in the environment. To prepare hamsters for infection and reduce other competing intestinal micro-organisms, all animals were pre-treated for 1 week with Emtryl (May & Baker, Dimetridazole at a concentration of 1 g/L in drinking water), then for another week with Terramycin (Pfizer, oxytetracycline hydrochloride, 3 g/L in drinking Carbohydrate water) and were returned to normal drinking water for 1 week prior to infection. Animals were used at approximately 8–12 weeks of age. The methods used to measure the height of villi, the depth of the Crypts of Lieberkühn and mitotic activity were described comprehensively by Alkazmi et al. (20). Methods for assessing the mast cell, goblet cell, eosinophil and Paneth cell responses were reported earlier in full (18). In all the histological observations reported here, we counted cells/mm2 of mucosal tissue on appropriately stained sections, using the Weible 2 graticule as described by Kermanizadeh et al. (29).