ABSTRACT
The aim of this study was to compare the short-term post-weaning behaviour of piglets treated either neutrally or aversively during the suckling period. A total of 24 lactating sows and their litters were housed in different rooms according to treatment. A female experimenter (P1) was in charge of feeding and cleaning from days 10 to 27 after birth. For the aversive treatment (Aver), P1 was noisy, moved harshly and unpredictably and shouted frequently during routine cleaning of facilities and animal handling. For the neutral treatment (Neut), P1 used a soft tone of voice and was careful during the same routine. At weaning, the avoidance response of piglets to an approaching experimenter in a novel place was assessed in four piglets from each litter. Scores ranged from 1 (experimenter could touch piglet) to 4 (piglet escaped as soon as person moved). The test was repeated twice, with a 1-h interval, with P1, who wore blue trousers and white T-shirt, and a second handler unfamiliar to the piglets (P2, who wore blue coveralls). Thereafter, litters from the same treatment were mixed and housed in separate rooms, balanced for gender and live weight (n = 12 groups of 4 piglets/treatment). Behaviour time budgets were registered by scan sampling every 2-min, for 4 h per day, for 4 days. Piglets were weighed at birth, at weaning and on day 5. Effects of treatment and handler on responses to the avoidance test were analysed with non-parametric tests and effects of treatment with a mixed model for repeated measures. Avoidance score was higher for Aver than Neut piglets when tested with P1 (P = 0.04) but not with P2 (P = 0.8). When piglets' responses to the different handlers were compared within each treatment, no significant differences were found. Frequencies of resting were lower (P < 0.001), whereas escape attempts (P < 0.03), agonistic interactions (P < 0.02) and frequency of presence at feeder (P < 0.001) were higher in the Aver than in the Neut groups. Feed and water intake and weight gain did not differ between treatments. We conclude that 4-week-old piglets can discriminate a handler according to the nature of treatment received during suckling. In addition, piglets treated aversively seem to have more difficulty adapting to weaning than those treated neutrally during the suckling period.
ABSTRACT
Antibody phage technology has greatly facilitated the isolation of good-quality monoclonal antibodies to virtually any target antigen. Large combinatorial phage display libraries of human antibodies are routinely being used for the identification of antibody candidates for clinical applications. However, preclinical studies in rodents would benefit from the availability of good-quality single-pot mouse antibody libraries, which at present are not available. In this article, we report on the construction of three mouse antibody phage display libraries, all containing over 1 billion antibody clones and all based on a similar library design, which featured the combinatorial mutagenesis of residues in the CDR3 loops of a given antibody scaffold. While all three libraries were found to express antibodies in bacterial supernatants, only one of them (termed "PHILOtop") was shown to reliably yield good-quality antibodies towards all protein antigens used so far in selection experiments, including three tumor-associated antigens. The modular structure of the PHILOtop library facilitates a simple affinity-maturation procedure based on the combinatorial mutagenesis of CDR1 and CDR2 loops of the VH domain, which has led to the isolation of a high-affinity antibody ("H7"; Kd=6 nM) specific to the EDB domain of fibronectin, a marker of angiogenesis. The single-pot antibody library PHILOtop may thus represent a useful source of binding specificities, facilitating preclinical studies in immunocompetent syngeneic mouse models of pathology.
