RESUMEN
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.
Asunto(s)
Crianza de Animales Domésticos/métodos , Calostro/inmunología , Infecciones por Haemophilus/veterinaria , Haemophilus parasuis/inmunología , Inmunidad Materno-Adquirida/inmunología , Enfermedades de los Porcinos/inmunología , Enfermedades de los Porcinos/microbiología , Animales , Animales Recién Nacidos , Anticuerpos Antibacterianos/sangre , ADN Bacteriano/química , ADN Bacteriano/genética , Modelos Animales de Enfermedad , Ensayo de Inmunoadsorción Enzimática/veterinaria , Femenino , Infecciones por Haemophilus/inmunología , Infecciones por Haemophilus/microbiología , Haemophilus parasuis/genética , Reacción en Cadena de la Polimerasa/veterinaria , Embarazo , Distribución Aleatoria , España , PorcinosRESUMEN
The bovine interleukin-15 (IL-15) sequence was cloned from abomasal lymph node mRNA by enzymatic amplification of cDNA using human primers proximal to and including the translation start and stop sites. The open reading frame is 486 base pairs in length, and the proposed protein sequence shows 78.4% and 73.5% similarity with that predicted for the human and mouse sequences, respectively. Expressed and purified recombinant bovine IL-15 in the absence of the 48-amino acid leader sequence stimulated the proliferation of bovine lymphoblast cells at least 12-fold over background at maximum concentration levels. Competitive reverse transcriptase-polymerase chain reaction analysis showed constitutive levels of IL-15 mRNA within a broad range of tissues and cell types. Lipopolysaccharide addition to adherent lymph node populations caused moderate increases in IL-15 transcription, whereas the addition of phorbol 12-myristate 13-acetate and calcium ionophore failed to induce gene expression for this cytokine. Transcription of IL-15 was also downregulated in the presence of low concentrations of human recombinant interleukin-2.