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African swine fever virus (ASFV) induces a variety of immune responses and clinical forms in domestic pigs. As it is the only member of the Asfarviridae family, ASFV encodes many novel genes not encoded by other virus families. Among these genes, A238L may regulate the synthesis of pro-inflammatory cytokines, controlled mainly by NFkappaB and NFAT pathways. In this study, we inoculated two groups of pigs, one with the ASFV highly virulent E-70 isolate, deleted on A238L gene, and the other group with the parental E-70 isolate. No significant differences were observed in the clinical signs or pathology between both groups. However, the TNF-alpha mRNA expression was strongly enhanced in the PBMC from pigs inoculated with the virus deleted in A238L, reinforcing the role of the A238L gene in the inhibition of the NFkappaB pathway of expression of cytokines. No up-regulation of pro-inflammatory cytokines was observed in the PBMC of animals inoculated with the E-70 isolate, even though apoptosis and haemorrhages were evident and might be related to the presence of bystander monocyte-macrophages expressing these cytokines. Other studies using ASFV deleted in other genes inoculated in the natural hosts should be performed to gain further insight into the role of these genes in the pathogenesis of ASF.

The aim of this study was to compare the development of Glasser's disease in sow-reared and colostrum-deprived piglets. Ninety piglets from a commercial pig farm in Spain were used. The farm was positive for Haemophilus parasuis. Fifty-two pigs were sow-reared (SR) and 38 were colostrum-deprived (CD) piglets. The animals were intratracheally inoculated with H. parasuis serovar 5 and sacrificed at 1, 2 and 3 days post-infection. To assess the development of disease, antibody titers, clinical signs, pathological lesions, microbiological isolation and PCR amplification were compared between the groups. Inoculation of SR pigs did not cause clinical signs or lesions of Glasser's disease. In SR pigs, H. parasuis isolation and specific PCR amplification from tissues showed a very low number of positive samples. In contrast, in CD pigs, inoculation resulted in the typical signs and lesions of Glasser's disease. Positive microbiological isolation and specific PCR products were obtained from the majority of the tissues tested, and no antibodies against H. parasuis were detected. The experimental infection using CD pigs describes a successful method to study this microorganism and confirms the important role that maternal antibodies play in protection against clinical signs and disease.