Dietary L-glutamine supplementation improves pregnancy outcome in mice infected with type-2 porcine circovirus.

Porcine circovirus type 2 (PCV2) causes reproductive failure in swine. As glutamine can enhance immune function in animals, this study was conducted with mice to test the hypothesis that dietary glutamine supplementation will improve pregnancy outcome in PCV2-infected dams. Beginning on day 0 of gestation, mice were fed a standard diet supplemented with 1.0% L-glutamine or 1.22% L-alanine (isonitrogenous control). All mice were infected with PCV2 (2000 TCID50) on day 10 of gestation. On day 17 of gestation, six mice from each group were euthanized to obtain maternal tissues and fetuses for hematology and histopathology tests. The remaining mice continued to receive their respective diets supplemented with 1.0% L-glutamine or 1.22% L-alanine through lactation. The PCV2 virus was present in maternal samples (serum and lung) of most mice in the control group but was not detected in the glutamine-supplemented mice. Dietary glutamine supplementation reduced abortion, decreased fetal deaths, and enhanced neonatal survival. The glutamine treatment also reduced concentrations of interleukin-6, while increasing concentrations of tumor necrosis factor-α and C-reactive protein, in the maternal serum of mice. Furthermore, glutamine supplementation attenuated microscopic lesions in maternal tissues (lung, spleen, and liver). Collectively, these results indicate that dietary glutamine supplementation is beneficial for ameliorating reproductive failure in virus-infected mice. The findings support the notion that gestating dams require adequate amounts of dietary glutamine for the optimal survival and growth of embryos, fetuses, and neonates, and have important implications for nutritional support of mammals (including swine and humans) during gestation and lactation.

DNA vaccine encoding the major virulence factors of Shiga toxin type 2e (Stx2e)-expressing Escherichia coli induces protection in mice.

Piglet edema disease is found worldwide and has historically been treated with antibiotics. However, no commercial vaccines are available for its prevention. In this study, the two major virulence factors of Shiga-toxigenic Escherichia coli (Stx2eB and FedF) were cloned to a pcDNA6.0 plasmid to develop a novel DNA vaccine against piglet edema disease. In animal trial in mouse model, the antibody titer, mortality, serum cytokine levels (interleukin-1 beta, interleukin-6, tumor necrosis factor alpha and C-reactive protein), serum malondialdehyde level and serum total superoxide dismutase activity were measured to validate the effectiveness of the DNA vaccine. The results show that Stx2eB and FedF at least partially protect against edema disease and FedF is more effective than Stx2eB. Co-immunization with both Stx2eB and FedF is most effective for protecting mice from a subsequent challenge with E. coli O139 (which is known to cause edema disease in pigs).

Effect of dietary arginine supplementation on reproductive performance of mice with porcine circovirus type 2 infection.

The objective of this study was to investigate whether supplemental dietary arginine increases reproductive performance in mice infected with porcine circovirus type2 (PCV2). A total of 50KM female mice were allotted randomly to the arginine group (0.6% arginine+gestation diet) and control group (1.22% alanine+gestation diet). All the mice began to mate after 14 days of treatment with our prepared feed and challenged with PCV2 at the dose of 100 TCID50 (50% tissue culture infection dose, TCID50) after 7 days of pregnancy. Abortion rate, litter number, litter birth weight, the daily weight gain in the first 7 days and survival rate in the first 2 weeks of the neonates were calculated. The serum progesterone, estrogen, nitric oxide and superoxide dismutase (SOD) activity and total antioxidant capacity (T-AOC) on the 14th day of pregnancy were measured. Arginine supplementation decreased the abortion rate of pregnant mice and mortality of neonates caused by PCV2 infection. Further, litter number, litter birth weight and the daily weight gain of neonates increased in the arginine group compared to the control group. Arginine supplementation increased significantly the serum progesterone (P<0.01) and nitric oxide levels (P<0.05), but had little effect on the serum estrogen level. SOD activity and T-AOC in the arginine group were significantly higher (P<0.01) than the control group. In conclusion, arginine supplementation partially reversed the reproductive failure in mice caused by PCV2 infection.