Pseudorabies virus induces a rapid up-regulation of nitric oxide synthases in the nervous system of swine.

Nitric oxide (NO) is a free radical gas with important roles in the host's immune response against viral infections. In this study, we examined the kinetics and distribution of nitric oxide synthase (NOS) expression during the early steps of infection of the porcine nervous system by the alphaherpesvirus pseudorabies virus (PRV). To this end, we examined changes in the expression of the three major NOS isoforms, neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS), by immunohistochemistry in the trigeminal ganglia and brain of pigs inoculated intranasally with a virulent PRV strain. The results obtained show that infection of the porcine nervous system by PRV induced a rapid and progressive increment in NOS expression that coincided in timing, location, and magnitude with those of virus propagation in the nervous tissue. A major finding of this study was that PRV caused not only nNOS and iNOS induction in a variety of cell types, but also eNOS up-regulation in endothelial cells and neurons; therefore, all possible sources of NO are activated and probably contribute to the overproduction of NO during infection with the neurotropic alphaherpesvirus PRV in its natural host.

Experimental intoxication by larvae of Perreyia flavipes Konow, 1899 (Hymenoptera: Pergidae) in pigs and some aspects on its biology.

Two pigs were dosed with 5 and 10g/kg bw of fresh Perreyia flavipes larvae collected at the municipality of Pelotas. Two other pigs were dosed with 0.87 and 1.7g/kg of dry P. flavipes (equivalent to 5 and 10g/kg bw of fresh larvae). Another pig was dosed with 0.17g/kg of dry larvae, daily, during 20d. Forty-eight hours after the ingestion, all pigs that ingested single doses showed clinical signs and marked rise in serum aspartate aminotransferase. Alanine aminotransferase and gamma glutamiltransferase were also slightly increased. The pig dosed with 10g/kg of fresh larvae died in 96h. The others recovered in 4-5days after ingestion. No clinical signs were observed in the pigs dosed during 20d with 0.17g/kg of dry larvae. The main lesion observed in the pig dosed whit 10g/kg of fresh larvae was a centrilobular liver necrosis. These results confirmed the toxicity of P. flavipes for swine, demonstrated that the larvae maintain the toxicity after being dried, and suggest no cumulative effect in the larval toxicity. The larvae collected in the field were conditioned in boxes containing swards of native grasses and covered with gauze to prevent the escape of adults on emergence. The larvae pupated from August 11 to September 25. Emergency of adults occurred from February 10 to March 4. Adult females and males live only for 18-36 and 24-48h, respectively. The eggs had an incubation period of 26-33d. The larval period extend from March 1 to August 24.