Isolates of Marek's disease virus (MDV) from vaccinated flocks in Argentina were characterized as very virulent (vv) and very virulent plus (vv+) strains. Experimental infection with these viruses caused a high incidence of Marek's disease in both resistant N-2a line and susceptible P-2a line birds. Vaccine viruses from each of the three Marek's disease viral serotypes were evaluated alone and in various combinations for protection against challenge with a vvMDV called NULP-1. Vaccination of P-2a birds with HVT did not protect satisfactorily against any of the vv and vv+MDV strains isolated. However, CVI988/Rispens vaccine alone or combined with serotype 2 and/or serotype 3 vaccine strains enhanced protection significantly against NULP-1. Serotype 2 plus serotype 3 vaccines also provided significant protection when challenged with this strain. This is one the first reports of the occurrence of vvMDV and vv+MDV in Argentina and Latin America. It is also a preliminary evaluation of the synergistic protective effect of different vaccine viruses with local MDV strains. However, further studies are needed to evaluate the real role of these and other Marek's disease isolates in 'vaccination failures' and the influence of serotype and virus strain on synergism between Marek's disease vaccine viruses.

No abstract

No abstract

ABSTRACT. Seven sites were examined in the Challhuaco-Ñireco system, located in the reserve of the Nahuel Huapi National Park, however part of the catchment is urbanized, being San Carlos de Bariloche (150,000 inhabitants) placed in the lower part of the basin. Physico-chemical variables were measured and benthic macroinvertebrates were collected during three consecutive years at seven sites from the headwater to the river outlet. Sites near the source of the river were characterised by Plecoptera, Ephemeroptera, Trichoptera and Diptera, whereas sites close to the river mouth were dominated by Diptera, Oligochaeta and Mollusca. Regarding functional feeding groups, collector-gatherers were dominant at all sites and this pattern was consistent among years. Ordination Analysis (RDA) revealed that species assemblages distribution responded to the climatic and topographic gradient (temperature and elevation), but also were associated with variables related to human impact (conductivity, nitrate and phosphate contents). Species assemblages at headwaters were mostly represented by sensitive insects, whereas tolerant taxa such as Tubificidae, Lumbriculidae, Chironomidae and crustacean Aegla sp. were dominant at urbanised sites. Regarding macroinvertebrate metrics employed, total richness, EPT taxa, Shannon diversity index and Biotic Monitoring Patagonian Stream index resulted fairly consistent and evidenced different levels of disturbances at the stream, meaning that this measures are suitable for evaluation of the status of Patagonian mountain streams. KEYWORDS.Patagonian, rivers, macroinvertebrates, biotic indexes, water quality. RESUMEN. Evaluación del rendimiento de distintas métricas utilizando los macroinvertebrados en el sistema lótico de Challhuaco-Ñireco (Patagonia, Argentina).Siete sitios fueron examinados en el sistema lótico Challhuaco-Ñireco, ubicado dentro del Parque Nacional Nahuel Huapi (PNNH), sin embargo parte de esta cuenca está urbanizada ya que atraviesa la ciudad de San Carlos de Bariloche (150,000 habitantes). Se midieron variables físico-químicas y se colectaron los macroinvertebrados bentónicos durante tres años consecutivos en siete sitios desde la cabecera hasta la desembocadura. Plecoptera, Ephemeroptera, Trichoptera y Diptera predominaron en los sitios cercanos a la cabecera, mientras que Diptera, Oligochaeta y Mollusca dominaron los sitios más bajos cercanos a la desembocadura. En relación con los grupos funcionales, los colectores-recolectores fueron los dominantes en todos los sitios y este patrón fue consistente durante los tres años de muestreo. El análisis de ordenamiento (RDA) reveló que las distribuciones de los ensambles de especies respondieron al gradiente climático y topográfico (temperatura y elevación), pero también fueron asociados con variables relacionadas al impacto antrópico (conductividad, contenido de nitratos y fosfatos). Los ensambles en cabecera estuvieron representados por insectos sensibles, mientras que los taxones tolerantes como Tubificidae, Lumbriculidae, Chiron...