RESUMEN
Chicken infectious anemia virus (CAV) is a worldwide-distributed infectious agent that affects commercial poultry. Although this agent was first detected in Argentina in 1994, no further studies on CAV in this country were reported after that. The recent increased occurrence of clinical cases of immunosuppression that could be caused by CAV has prompted this study. Our results confirmed that CAV is still circulating in commercial flocks in Argentina. Phylogenetic analysis focusing on the VP1 nucleotide sequence showed that all Argentinean isolates grouped together in a cluster, sharing a high similarity (> 97%) with genotype B reference strains. However, Argentinean isolates were distantly related to other strains commonly used for vaccination in this country, such as Del-Ros and Cux-1. Sequence analysis of predicted VP1 peptides showed that most of the Argentinean isolates have a glutamine residue at positions 139 and 144, suggesting that these isolates might have a reduced spread in cell culture compared with Cux-1. In addition, a particular amino acid substitution at position 290 is present in all studied Argentinean isolates, as well as in several VP1 sequences from Malaysia, Australia, and Japan isolates. Our results indicate that it is possible to typify CAV strains by comparison of VPI nucleotide sequences alone because the same tree topology was obtained when using the whole genome sequence. The molecular analysis of native strains sheds light into the epidemiology of CAV in Argentinean flocks. In addition, this analysis could be considered in future control strategies focused not only on breeders but on broilers and layer flocks.
Asunto(s)
Virus de la Anemia del Pollo/genética , Pollos , Infecciones por Circoviridae/veterinaria , Enfermedades de las Aves de Corral/virología , Secuencia de Aminoácidos , Animales , Argentina/epidemiología , Secuencia de Bases , Proteínas de la Cápside/genética , Proteínas de la Cápside/metabolismo , Infecciones por Circoviridae/epidemiología , Infecciones por Circoviridae/virología , Regulación Viral de la Expresión Génica , Epidemiología Molecular , Filogenia , Enfermedades de las Aves de Corral/epidemiologíaRESUMEN
Minimum inhibitory concentrations (MICs) were determined in vitro for 7 antibiotics (aivlosin, enrofloxacine, tylosin, tiamulin, kitasamycin, chlortetracycline, and oxytetracycline) against eight recent local Argentinean isolates and two standard strains of Mycoplasma synoviae. Aivlosin (3-acetyl-4"-isovaleryl tylosin tartrate), tylosin, and tiamulin showed the lowest MICs with MIC90s of 0.006, 0.012, and 0.05 microg/ml, respectively. Except one strain that showed resistant values to chlortetracycline (> or = 12.5 microg/ml), all the analyzed strains were susceptible in different degrees to all the antibiotics tested. In this study, the improved activity of the tylosin-derived drug, aivlosin, was confirmed because it showed, in most strains, MIC values half those for tylosin.
Asunto(s)
Antibacterianos/farmacología , Mycoplasma/efectos de los fármacos , Tilosina/análogos & derivados , Argentina , Medios de Cultivo , Farmacorresistencia Bacteriana , Pruebas de Sensibilidad Microbiana/veterinaria , Mycoplasma/crecimiento & desarrollo , Tilosina/farmacologíaRESUMEN
Several mycoplasma species produce various diseases in different animal species. M. bovis has been described as the cause of mastitis, arthritis, pneumonia and infertility in cattle. Furthermore, this species has been the most frequently isolated agent producing bovine mastitis. The objective of this study was to isolate and typify mycoplasma strains from a clinical mastitis outbreak in a dairy farm of Buenos Aires Province. A total of 279 samples were studied (276 from pooled quarter milk of cows with clinical mastitis that did not respond to antibiotic therapy, 1 from bulk tank milk and 2 preputial swabs from bulls). The isolated mycoplasma strains (n = 12) were further characterized by biochemical analysis, serological studies and electrophoretic analysis of the protein profiles (SDS-PAGE). Based upon these studies, the isolated strains were identified as Mycoplasma bovis. This is the first report of isolation of this microorganism in Argentina. Therefore the results described here could be very useful to improve mastitis control in dairy farms.