PSLBII-16 Assessing endotoxin or <i>Escherichia coli</i> vaccine administration during gestation as a means to alter postnatal immune function in pigs

Abstract Previous research demonstrated that low-dose endotoxin (LPS) administered during gestation can attenuate the postnatal response to LPS in weaned piglets. The follow-up study was designed to determine whether exposure to low dose LPS or a commercial Escherichia coli vaccine during gestation can alter immunity to an LPS challenge in piglets after weaning. Pregnant gilts were assigned to prenatal immune stimulation (PIS; n = 4; administered 2.5 µg/kg body weight (BW) LPS i.m. at d 77 ± 2.3 of gestation), vaccine (VAX; n = 3; administered LitterGuard-LTC i.m. at d 77 and 94 ± 1.7 of gestation), or saline treatment groups (CON; n = 3). From the three prenatal treatment groups, barrows (n = 13 PIS, 13 VAX, 14 CON) were identified at weaning (21 ± 1.9 d of age) to subsequently receive a post-weaning LPS challenge. On d -5, barrows were transported and housed in individual, indoor pens with ad libitum access to water and a starter ration. On d -1, pigs were fitted with indwelling jugular catheters and subcutaneous temperature loggers. On d 0, pigs were administered LPS (10 µg/kg BW i.v.), and blood samples were collected at -2, 0, 1, 2, 4, 6, 8, and 24 h relative to LPS challenge. Data were analyzed using PROC MIXED in SAS, specific for repeated measures. There was a tendency (P = 0.10) for a treatment effect for sow vaginal temperature, measured using indwelling logger, where PIS sows had greater vaginal temperature than CON sows, with VAX being intermediate. There was a treatment × time interaction (P = 0.02) for the change in lymphocyte concentration relative to pre-challenge values, where PIS piglets had less change in lymphocyte concentrations at 2 and 4 h compared with CON, and 8 h compared with CON and VAX piglets. Additionally, there was a treatment effect (P = 0.01) for neutrophil:lymphocyte ratio, where PIS piglets had a greater ratio compared with CON and VAX piglets. There was a treatment × time interaction (P = 0.04) for piglet subcutaneous body temperature, where PIS piglets had reduced temperature from 3 to 5 h compared with CON, and at 2 and from 4 to 7 h compared with VAX piglets. There was a tendency (P = 0.09) for a treatment effect for spleen length measured 24 h post-LPS administration where length was shorter in PIS compared with CON piglets, with VAX being intermediate. While data analysis continues for this study, these initial data support previous data suggesting an attenuated immune response to postnatal LPS when pigs are exposed to LPS in utero. Further, pigs exposed to an E. coli vaccine during gestation appear to respond similarly to CON pigs. These data add to available information on the ability to alter immunity of pigs in utero in an effort to positively influence piglet health after birth.