Hepatitis por corpúsculos de inclusión. I. Aislamiento de un virus

Se aisló un virus a partir de una suspensión de hígados sospechosos de hepatitis por corpúsculos de inclusión. El virus HCI-6 tuvo algunas características del grupo adeno y fue capaz de reproducir la enfermedad en pollitos

Role of Position 627 of PB2 and the Multibasic Cleavage Site of the Hemagglutinin in the Virulence of H5N1 Avian Influenza Virus in Chickens and Ducks

Highly pathogenic H5N1 avian influenza viruses have caused major disease outbreaks in domestic and free-living birds with transmission to humans resulting in 59% mortality amongst 564 cases. The mutation of the amino acid at position 627 of the viral polymerase basic-2 protein (PB2) from glutamic acid (E) in avian isolates to lysine (K) in human isolates is frequently found, but it is not known if this change affects the fitness and pathogenicity of the virus in birds. We show here that horizontal transmission of A/Vietnam/1203/2004 H5N1 (VN/1203) virus in chickens and ducks was not affected by the change of K to E at PB2-627. All chickens died between 21 to 48 hours post infection (pi), while 70% of the ducks survived infection. Virus replication was detected in chickens within 12 hours pi and reached peak titers in spleen, lung and brain between 18 to 24 hours for both viruses. Viral antigen in chickens was predominantly in the endothelium, while in ducks it was present in multiple cell types, including neurons, myocardium, skeletal muscle and connective tissues. Virus replicated to a high titer in chicken thrombocytes and caused upregulation of TLR3 and several cell adhesion molecules, which may explain the rapid virus dissemination and location of viral antigen in endothelium. Virus replication in ducks reached peak values between 2 and 4 days pi in spleen, lung and brain tissues and in contrast to infection in chickens, thrombocytes were not involved. In addition, infection of chickens with low pathogenic VN/1203 caused neuropathology, with E at position PB2-627 causing significantly higher infection rates than K, indicating that it enhances virulence in chickens

Avian immunology, 2nd ed./ Edit.: Karel

439 hal.: ill, tab.; 28 cm

Avian immunology, 2nd ed./ Edit.: Karel

439 hal.: ill, tab.; 28 cm

Reproductive effort reduces long-term immune function in breeding tree swallows (Tachycineta bicolor).

We examined whether strategies of reproductive allocation may reduce long-term immunocompetence through the effects of manipulated effort on secondary or acquired immunity. We tested whether increased reproductive effort leads to reduced immune function and survival by manipulating brood size in tree swallows (Tachycineta bicolor) and exposing breeding females to a primary and secondary exposure of sheep red blood cells to elicit a humoral immune response. Females raising enlarged broods produced fewer secondary antibodies than did females raising control or reduced broods. Most importantly, individuals with high secondary responses were more likely to survive to breed 3 years after brood manipulations, suggesting that differences in disease susceptibility may be caused by trade-offs in reproductive allocation. We also found that individual quality, measured by clutch initiation date, mediated the effects of brood manipulations, with higher-quality birds showing a greater ability to deal with increases in effort

Positive and Negative Regulation of Chicken Anemia Virus Transcription

Chicken anemia virus (CAV) is a small circular single-stranded DNA virus with a single promoter-enhancer region containing four consensus cyclic AMP response element sequences (AGCTCA), which are similar to the estrogen response element (ERE) consensus half-sites (A)GGTCA. These sequences are arranged as direct repeats, an arrangement that can be recognized by members of the nuclear receptor superfamily. Transient-transfection assays which use a short CAV promoter construct that ended at the transcription start site and drive expression of enhanced green fluorescent protein (EGFP) showed high basal activity in DF-1, LMH, LMH/2A, and primary theca and granulosa cells. The estrogen receptor-enhanced cell line, LMH/2A, had significantly greater expression than LMH cells, and this expression was significantly increased with estrogen treatment. A long promoter construct which included GGTCA-like sequences downstream of the first CAV protein translation start site was found to have significantly less EGFP expression in DF-1 cells than the short promoter, which was largely due to decreased RNA transcription. DNA-protein binding assays indicated that proteins recognizing a consensus ERE palindrome also bind GGTCA-like sequences in the CAV promoter. Estrogen receptor and other members of the nuclear receptor superfamily may provide a mechanism to regulate CAV activity in situations of low virus copy number

A. Schat, Karel

-Instituto Nacional de Investigaciones Forestales, Agrícolas y Pecuaria

Ecoimmunology

Ecoimmunology provides an evolutionary perspective on immunity through the examination of the costs and benefits of investment in the immune system. In this chapter, we review key research areas, techniques and future directions in ecoimmunology, particularly as these pertain to free-living birds. Assays to assess immune function in the field vary depending on the defenses and parasites of interest as well as the ability to repeatedly sample free-living individuals. Several new field assays seek to measure innate immune responses. These include the acute-phase response, which integrates physiological and behavioral changes following infection. Recent work on the major histocompatibility complex (MHC) in an ecological context has found that MHC diversity correlates with disease dynamics in several free-living bird species. Development of the immune system in free-living birds is still understudied, especially in altricial species that develop slowly in the nest. Maternal antibody transmission remains a critical area of study, as it can provide significant pathogen resistance benefits but may carry significant costs to offspring immune ontogeny. Lastly, we discuss the important role of immune system costs, both in resources and immunopathology, in driving life history trade-offs and variation in sexually selected signals. © 2014 Elsevier Ltd All rights reserved