PubMed Health⌕ Search

Biomedical subjects

D N Phalen

Publications and source records attributed to D N Phalen.

17 recordsLinked to original sources
PubMed2001

Detection and heterogeneity of herpesviruses causing Pacheco's disease in parrots.

Pacheco's disease (PD) is a common, often fatal, disease of parrots. We cloned a virus isolate from a parrot that had characteristic lesions of PD. Three viral clones were partially sequenced, demonstrating that this virus was an alphaherpesvirus most closely related to the gallid herpesvirus 1. Five primer sets were developed from these sequences. The primer sets were used with PCR to screen tissues or tissue culture media suspected to contain viruses from 54 outbreaks of PD. The primer sets amplified DNA from all but one sample. Ten amplification patterns were detected, indicating that PD is caused by a genetically heterogeneous population of viruses. A single genetic variant (psittacid herpesvirus variant 1) amplified with all primer sets and was the most common virus variant (62.7%). A single primer set (23F) amplified DNA from all of the positive samples, suggesting that PCR could be used as a rapid postmortem assay for these viruses. PCR was found to be significantly more sensitive than tissue culture for the detection of psittacid herpesviruses.

Animals↗
PubMed2000

Viremia, virus shedding, and antibody response during natural avian polyomavirus infection in parrots.

OBJECTIVE: To determine rapidity of spread and onset and duration of viremia, virus shedding, and antibody production in parrots naturally infected with avian polyomavirus (APV). DESIGN: Case series. ANIMALS: 92 parrots in 2 aviaries. PROCEDURE: Blood samples were obtained from parrots naturally exposed to APV during a 3- to 4-month period for determination of serum virus neutralizing antibody and detection of viral DNA. Nestlings from the next year's hatch were monitored for APV infection. RESULTS: The first indication of inapparent infection was viremia, which developed simultaneously with or was followed within 1 week by cloacal virus shedding and antibody production. Cloacal virus shedding continued after viremia ceased. During viremia, viral DNA was detected continuously in blood samples. Viral DNA was detected in serial cloacal swab specimens in most birds, but it was detected inconsistently in 6 birds and not detected in 3 birds, even though these birds were viremic. Duration of cloacal virus shedding was < or = 4.5 months. In 1 aviary, prevalence of infection was 88% and dissemination of virus through the 3-room building required 4.5 months. In the second aviary, a single-room nursery, prevalence of infection was > or = 90%. For all affected birds, infection could be detected 18 days after the first death. CONCLUSIONS AND CLINICAL RELEVANCE: If a single sampling is used for polymerase chain reaction detection of viral DNA, blood and cloacal swab specimens are required. In nestling nonbudgerigar parrots, cloacal virus shedding may persist for 4.5 months. Management protocols alone are sufficient to prevent introduction of APV into a nursery.

Animals↗
PubMed2000

Respiratory medicine of cage and aviary birds.

Respiratory diseases are a relatively common cause of illness and death in cage birds. A diagnostic algorithm is provided based on history, physical examination, and ancillary diagnostic findings that assist clinicians in determining the cause of a bird's respiratory disease. Also included are detailed descriptions of the common respiratory diseases of cage birds and their treatment.

Algorithms↗
PubMed2000

Isolation and characterization of an avian isolate of Encephalitozoon hellem.

Members of the phylum Microspora are a group of unusual, obligate intracellular eukaryotic parasites that infect a wide range of hosts. However, there are a limited number of microsporidial infections reported in avian hosts, and no parasite species has been defined as an avian pathogen. A microsporidian organism was recovered from the droppings of a clinically normal peach-faced lovebird (Agapornis roseicollis) and established in in vitro culture. Intermittent parasite spore shedding was documented over a 2-month period using calcofluor M2R staining of cloacal swabs. The organism was identified as Encephalitozoon hellem based on protein and antigenic profiles and molecular sequencing of the small subunit and internal transcribed spacer regions of the ribosomal RNA gene.

Animals↗
PubMed1999

Partial tracheal obstruction due to chondromas in ball pythons (Python regius).

Over a 9-mo period, three adult ball pythons (Python regius) (one male, two females) were evaluated for severe dyspnea. Partial obstructions of the tracheal lumen were identified radiographically and/or visualized with a 3.0-mm rigid laparoscope inserted into the tracheal lumen in all three snakes. Administration of systemic antibiotics and nebulization resulted in partial improvement of the dyspnea. In two snakes, the tracheal lesions were removed with a rigid laparoscope and a flexible biopsy instrument inserted into the tracheal lumen. The other snake died and was necropsied. Histologically, the lesions from two snakes were determined to be benign chondromas. The chondromas were composed of a variably disorganized chondroid matrix populated by quiescent, normal-appearing chondrocytes within lacunae, although the chondrocytes were increased in density compared with normal hyaline cartilage and contained rare mitotic figures. The tracheal masses in one snake grew by expansion, not invasion, and were focally continuous with a mineralized cartilage tracheal ring, suggesting a benign nature. This is the second report of tracheal chondroma in ball pythons. Tracheal chondromas are exceedingly rare in humans and domesticated animals, suggesting a possible predisposition of ball pythons for this neoplasm.

Animals↗
PubMed1996

Heart failure in a macaw with atherosclerosis of the aorta and brachiocephalic arteries.

A female severe macaw (Ara severa) that was at least 11 years old was evaluated for sudden onset of exercise intolerance and dyspnea. Radiography revealed a large heart silhouette, an increase in prominence of the brachiocephalic arteries, and a diffuse increase in opacity of the lungs. Lateral nonselective angiography revealed dilatation of both chambers of the right side of the heart and incomplete emptying of the right atrium. Alterations in the shape and position of the left-side heart chambers and reduction in blood flow through the brachiocephalic arteries and aorta were identified. Despite treatment, the bird died suddenly 2.5 months after the first episode of dyspnea. At necropsy, severe atherosclerosis of the aorta and brachiocephalic arteries, dilatation of all heart chambers, pulmonary edema, and severe hepatic centrolobular atrophy and fibrosis were identified. Correlation between the angiography and necropsy findings suggested that angiography could be an important diagnostic tool for the detection of cardiovascular disease in birds.

Angiography↗
PubMed1995

Hemograms and hematozoa of sharp-shinned (Accipiter striatus) and Cooper's hawks (Accipiter cooperii) captured during spring migration in northern New York.

Hemograms were determined for 26 Cooper's (Accipiter cooperii) and 55 sharp-shinned hawks (Accipiter striatus) captured during spring migration (27 March to 12 May 1987) on the south shore of Lake Ontario, New York (USA). No significant differences were noted in packed cell volume and estimated total solids between the species. However, Cooper's hawks had significantly higher total white blood cells counts and higher concentrations of heterophils, monocytes, and eosinophils. Proportionally, lymphocytes made up a smaller percentage of the differential count in the Cooper's hawk. Eosinophil concentrations and percentages of the differential count were significantly higher in the females of both species. Both species had a high prevalence of Leucocytozoon toddi and Haemoproteus spp. infection. Haemoproteus nisi and H. elani were identified in both hawks. Trypanosoma avium was identified in a single Cooper's hawk and Plasmodium circumflexum was identified in a sharp-shinned hawk. Prevalence of Leucocytozoon toddi and Haemoproteus spp. infections were significantly higher in the birds caught late in the spring as compared to those caught earlier in the spring; this was evidence for a spring recrudescence of patent parasite infections.

Animals↗
PubMed1993

Organ distribution of avian polyomavirus DNA and virus-neutralizing antibody titers in healthy adult budgerigars.

Tissue specimens and serum samples obtained from adult budgerigars in various stages of reproduction housed in an aviary with enzootic avian polyomavirus (APV) disease were examined by means of polymerase chain reaction techniques for APV DNA. Although the birds were apparently healthy, APV DNA could be detected in all 40 birds examined (inapparent infection rate, 100%). Viral DNA was found in most organ systems examined. Analysis of data suggested that organ virus concentrations were lower in breeding than in nonbreeding birds. Serum samples from 144 birds were examined for virus-neutralizing (VN) antibody. All serum samples had detectable VN antibody titers. Determining VN titer had a sensitivity of 100% for detection of APV infection in birds and was more sensitive than analysis of droppings by use of polymerase chain reaction techniques to detect APV infection in 6-month-old birds. Analysis of the data suggested that lower VN antibody titers were associated with longer duration of continuous breeding.

Animals↗
PubMed1991

Polymerase chain reaction assay for avian polyomavirus.

A polymerase chain reaction assay was developed for detection of budgerigar fledgling disease virus (BFDV). The assay used a single set of primers complementary to sequences located in the putative coding region for the BFDV VP1 gene. The observed amplification product had the expected size of 550 bp and was confirmed to derive from BFDV DNA by its restriction digestion pattern. This assay was specific for BFDV and highly sensitive, being able to detect as few as 20 copies of the virus. By using the polymerase chain reaction, BFDV was detected in adult, nestling, and embryo budgerigar (Melopsitticus undulatus) tissue DNAs and in sera from adult and nestling budgerigars. These results suggest the possibility of persistent infections in adult birds and lend further support to previously described evidence of possible in ovo transmission. BFDV was also detected in chicken embryo fibroblast cell cultures and chicken eggs inoculated with the virus. A 550-bp product with identical restriction enzyme sites was amplified from a suspected polyomavirus isolated from a peach-faced lovebird (Agapornis pesonata) and from tissue DNA from a Hahn's macaw (Ara nobilis) and a sun conure (Aratinga solstitialis) with histological lesions suggestive of polyomavirus infection. These fragments also hybridized with a BFDV-derived probe, proving that they were derived from a polyomavirus very similar, if not identical, to BFDV.

Animals↗
PubMedDate not supplied

Genetic diversity in twenty variants of the avian polyomavirus.

To determine if different pathotypes of the avian polyomavirus (APV) exist and to compare the genomes of APVs originating from different geographic areas, dates, and species of birds, the partial sequences of 18 APVs were determined. New viral sequences were compared with three published APV sequences. Two of the new viruses had identical sequences. Forty point mutations were found at 31 loci. A 27-bp deletion was found in the VP2 and VP3 open reading frames of one virus. A duplication of the putative origin of replication and adjacent enhancer region was previously reported in one APV. Smaller duplications involving the origin in one APV and a second enhancer region in another were discovered. All duplications were in tissue culture-adapted viruses, suggesting they occurred during the isolation process. Excluding duplications and the deletion, maximum variation between viruses was small (11 bp). A maximum parsimony tree was constructed that contained three major branches. The three earliest isolates were on separate branches. The European viruses were confined to branch I, but APVs from the United States were on all three branches. Lovebird, budgerigar, and macaw APVs were also on each of the three branches, suggesting that species-specific pathotypes have not developed. Most nonsynonymous mutations occurred in a small portion of the VP2 and VP3 open reading frames, demonstrating a selection for these mutations. That a glycine at VP2 221 will inhibit virus replication in chicken embryo fibroblasts (CEFs) has been previously reported. In contrast, six of seven of the new APVs isolated in CEFs had a glycine at VP2 221.

Amino Acid Substitution↗
PubMedDate not supplied

Avian polyomavirus infection and disease in a green aracaris (Pteroglossus viridis).

Avian polyomavirus (APV) is one of the most significant pathogens of domestically raised psittacine birds (parrots). One or more APVs are suspected to infect nonpsittacine cage birds, but the relationship of these viruses to the APV infecting parrots remains unclear. In this report, for the first time, we fully document an APV infection in a nonpsittacine cage bird, a green aracaris (Pteroglossus viridis). Grossly, this bird evidenced generalized hemorrhage. Histologically, there was severe hepatic necrosis, splenic necrosis, and the presence of lightly basophilic to clear pannuclear inclusion bodies and karyomegaly in splenocytes and renal mesangeal cells, all characteristic lesions of APV infection in parrots. APV DNA was amplified directly from the liver by polymerase chain reaction and sequenced. The virus differed from the original APV sequence by only 24 base pairs (0.48% of the genome), demonstrating that it is a variant of the APV. A serologic survey of the remaining birds in the aviary demonstrated anti-APV antibody in two cockatoos, two cockatiels, a laughing kookaburra, a Lady Ross turaco, and five zebra finches. The remaining green aracaris was seronegative. The sequence and serologic data suggest that the APV that infected the green aracaris originated in a parrot and was capable of infecting birds from at least four orders.

Animals↗
PubMedDate not supplied

Elementary body agglutination for rapidly demonstrating chlamydial agglutinins in avian serum with emphasis on testing cockatiels.

The development and use of a stained chlamydial elementary body agglutination (EBA) antigen for detecting antibody activity in avian sera is described. Examples of serologic results on serum samples from various types of birds indicate the usefulness of EBA, latex agglutination (LA), and direct complement fixation (DCF) in diagnosing avian chlamydiosis. Results of tests on 10 cockatiels examined in clinics indicate that a combination of serology, culture, and/or antigen-detection enzyme-linked immunosorbent assay may be helpful when testing this type of bird. Agreement between EBA, LA, and DCF was 81.8% when testing 407 serum samples from cockatiels of unknown health status. The relationship between positive (> or = 10 titer) antibody activity and known health status of 77 cockatiels revealed that agreement between the two criteria was only 59.7%. Of 13 Chlamydia-inoculated cockatiels, seven birds seroconverted from negative to positive by EBA; five seroconverted by DCF. Only the five birds that seroconverted by both EBA and DCF were culture-positive for chlamydiae. None of 15 sham-inoculated control cockatiels developed detectable antibody activity, and none of 10 cultured were positive. In tests with column-separated IgM and IgG, EBA detected only IgM activity, LA detected IgM and IgG activity, and DCF detected only IgG activity.

Agglutination Tests↗
PubMedDate not supplied

Chlamydia latex agglutination antigen and protocol improvement and psittacine bird anti-chlamydial immunoglobulin reactivity.

Latex agglutination detection of chlamydial antibody activity in psittacine bird sera was significantly more sensitive when an improved protocol was followed than was a test using the previously used protocol. Titers of antibody-positive sera were fourfold to 32-fold higher by the improved protocol than titers by the previously used protocol, whereas antibody-negative sera were negative by both protocols. Column chromatography was used to separate immunoglobulins in psittacine bird serum. Immunoglobulin M was reactive in latex agglutination (LA) but non-reactive in direct complement fixation (DCF). Immunoglobulin G was reactive in LA and DCF. The fifth supernatant fluid of serum multiply absorbed with latex beads was non-reactive in LA and DCF. The immunoglobulins reactive in LA had high avidity and affinity for latex beads. Prolonged storage at 4 C to 6 C preserved LA reactivity of absorbed immunoglobulins better than storage at 21 C to 23 C.

Animals↗
PubMedDate not supplied

Characterization of the avian polyomavirus-associated glomerulopathy of nestling parrots.

The glomerulopathy occurring in nestling nonbudgerigar parrots with avian polyomavirus (APV) disease was examined in 10 parrots. Glomerular lesions were characterized by the presence of dense, periodic acid-Schiff (PAS)-positive material that expanded the mesangium and that narrowed and at times occluded capillary lumina. PAS-staining was found to be more sensitive than hematoxylin and eosin in the detection of the lesions. Ultrastructurally, finely granular electron-dense material was found in massive intracapillary and mesangial condensates. Capillary endothelial cells exhibited changes consistent with cellular swelling. No evidence of chronic glomerular changes was observed. Immunofluorescent staining demonstrated that the PAS-positive, electron-dense condensates were complexes of IgG, avian polyomavirus antigen, and, in one bird, IgM. Viral DNA was detected in the serum of all six birds examined. Anti-APV antibodies were also present in all five serum samples examined. These findings suggested that the pathogenesis of this acute immune complex glomerulopathy and other APV-associated lesions depends on the presence of an appropriate ratio of circulating virus and anti-APV antibody.

Animals↗
PubMedDate not supplied

Failure of maternally derived yolk IgG to reach detectable concentrations in the sera of nestling budgerigars (Melopsittacus undulatus).

Transfer of maternal immunoglobulin G (IgG) to the yolk and nestling was investigated in the budgerigar. Specific antibodies to avian polyomavirus and Newcastle disease virus could be detected in 82% of yolk extracts of eggs from seropositive hens. Using a double immunodiffusion assay with anti-chicken IgG antibodies, IgG could also be detected in yolk supernatants with virus neutralizing activity. In all assays, IgG concentrations in the yolk extracts were significantly less than those of the adult budgerigar serum. No antiviral activity was detected in nestling serum. Examination of nestling serum with the double immunodiffusion assay and an immuno-dot-blot technique specific for IgG showed that detectable concentrations of IgG are not present in nestling serum until after the yolk sac is fully absorbed. This observation, coupled with the absence of specific anti-viral antibody in nestlings of seropositive hens, indicated that none of the yolk sac antibody reached the nestling circulation.

Animals↗
PubMedDate not supplied

Production of avian polyomavirus seronegative budgerigars (Melopsittacus undulatus) from seropositive adults.

Adult budgerigars (Melopsittacus undulatus) with 2 years of breeding experience were removed from an aviary with enzootic avian polyomavirus (APV) disease and maintained in an isolation unit. Following a 7-month respite from breeding, these birds were allowed to breed without interruption for 2 years. Although the adults were seropositive both at the beginning and end of the experiment, all 102 of their offspring were seronegative. These data suggest that APV can be eliminated from a budgerigar aviary with the use of simple management techniques.

Animal Husbandry↗