ABSTRACT
A novel herpesvirus infection in nine Bourke's parrots (Neopsephotus bourkii, formerly Neophema bourkii) housed in an outdoor aviary comprised of multiple species of birds was diagnosed based on histopathology, electron microscopy and polymerase chain reaction (PCR). Clinical signs in the parrots included anorexia, ruffled feathers, depression, loss of weight and respiratory distress. The most common gross lesions were moderately congested and oedematous lungs and a mild fibrinous exudate in the air sacs and lumen of the trachea. Histological examination revealed mild to severe bronchopneumonia and airsacculitis with syncytial cells containing eosinophilic intranuclear inclusion bodies in most birds. Other less frequent changes included tracheitis, syringitis, sinusitis, rhinitis, otitis media and conjunctivitis. Attempts to culture the virus in chicken embryos and chicken embryo liver cells were unsuccessful. Examination by transmission electron microscopy of syncytial cells from the lungs of two birds revealed intranuclear virus particles typical of the family Herpesviridae. DNA from a novel herpesvirus was amplified from lung tissue by PCR using degenerate primers derived from conserved avian herpesvirus sequences. The virus belongs in the genus Iltovirus of the Alphaherpesvirinae subfamily. It is not closely related to Psittacid herpesvirus 1 that causes Pacheco's disease but does group phylogenetically with a clade of herpesviruses that cause respiratory disease in a number of avian species. The proposed name for this herpesvirus is Psittacid herpesvirus 3.
Subject(s)
Bird Diseases/epidemiology , Disease Outbreaks/veterinary , Herpesviridae Infections/veterinary , Iltovirus/isolation & purification , Parrots , Respiratory Tract Infections/veterinary , Animals , Base Sequence , Bird Diseases/pathology , Bird Diseases/virology , California/epidemiology , DNA Primers/genetics , DNA, Viral/chemistry , DNA, Viral/genetics , Ear/pathology , Herpesviridae Infections/epidemiology , Herpesviridae Infections/pathology , Herpesviridae Infections/virology , Iltovirus/classification , Iltovirus/genetics , Lung/pathology , Lung/virology , Microscopy, Electron, Transmission/veterinary , Molecular Sequence Data , Phylogeny , Polymerase Chain Reaction/veterinary , Respiratory Tract Infections/epidemiology , Respiratory Tract Infections/pathology , Respiratory Tract Infections/virology , Retrospective Studies , Sequence Analysis, DNA/veterinary , Trachea/pathologyABSTRACT
A standardised nested-PCR method that amplifies a region of the glycoprotein E gene of avian infectious laryngotracheitis virus (ILTV) has been developed for the diagnosis of infection by Gallid herpesvirus 1. The two sets of primers employed produced the expected amplification products of 524 bp (external primers) and 219 bp (internal primers) in the presence of ILTV DNA, whereas no such amplicons were obtained with other avian respiratory pathogens or with DNA extracted from the cells of uninfected chickens. The identity of the 219 bp amplified product was confirmed by DNA sequencing. The standardised nested-PCR method detected ILTV DNA from trachea, lung, conjunctiva and trigeminal ganglia samples from flocks of birds with and without clinical signs, and showed high sensitivity (95.4%) and specificity (93.1%) when compared with the reference test involving virus isolation in specific-pathogen-free chicken embryos. The standardised nested-PCR method described may be used to detect clinical and latent ILTV infections, and will be of significant value for both diagnostic and epidemiological studies.
Subject(s)
Herpesviridae Infections/diagnosis , Iltovirus/genetics , Iltovirus/isolation & purification , Polymerase Chain Reaction/methods , DNA Primers , DNA, Viral/genetics , DNA, Viral/isolation & purification , Gene Amplification , Humans , RNA, Viral/genetics , RNA, Viral/isolation & purification , Reproducibility of ResultsABSTRACT
Infectious laryngotracheitis (ILT) is a severe acute respiratory disease of chickens caused by ILT virus. To better understand the epidemiology of the disease, a polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) assay of the glycoprotein E gene has been developed and utilized to characterize vaccine strains and outbreak-related isolates. Enzymes EaeI and DdeI were used to differentiate the tissue culture origin (TCO) vaccine from chicken embryo origin (CEO) vaccines. Two RFLP patterns were observed with enzyme EaeI, one characteristic of the TCO vaccine and a second characteristic of all CEO vaccines. Three RFLP patterns were observed with enzyme DdeI. Patterns A and B were characterized as single patterns, whereas the type C pattern was a combination of patterns A and B. Analysis of vaccine strains showed the presence of patterns A and C. Pattern A was observed for the TCO vaccine and one CEO vaccine, whereas pattern C was observed for five of the six CEO vaccines analyzed. PCR-RFLP analysis of plaque-purified virus from pattern C CEO vaccine preparations demonstrated the presence of two populations (patterns A and B). Identification of molecularly different populations of viruses within currently used ILT vaccine is the first step to develop better molecular epidemiologic tools to track vaccine isolates in the field.
