A serologic survey for avian polyomavirus and Pacheco's disease virus in Australian cockatoos.

Sera collected from wild and captive Australian cockatoos and other psittacine species (n = 411) were tested for antibodies to avian polyomavirus (APV) and Pacheco's disease virus (PDV). Of 144 wild sulphur-crested cockatoos (Cacatua galerita) sampled at three regions in New South Wales (NSW) 96 (64.4%) birds had positive (>/= 1:32) neutralizing antibody titres to avian polyomavirus (range 1:32-1:2048). Two of 17 wild long-billed corellas (Cacatua tenuirostris) were also APV-antibody positive. However, no samples from 107 wild galahs (Eolophus roseicapillus) were positive for neutralizing antibody to APV. Sera were also collected from captive psittacine bird flocks from NSW, Tasmania, Victoria, and Western Australia. In a mixed aviary of cockatoos and lorikeets, APV antibody was detected in sera from sulphur-crested cockatoos, Major Mitchell's cockatoos (Cacatua leadbeateri), a white-tailed black cockatoo (Calyptorhynchus baudinii latirostris), a red-tailed black cockatoo (Calyptorhynchus magnificus) a single galah, a rainbow lorikeet (Trichoglossus haematodus), and a scaley-breasted lorikeet (Trichoglossus chlorolepidotus). All 411 wild and captive birds were negative for the presence of neutralizing antibody to PDV. These results indicate that wild sulphur-crested cockatoos in NSW are enzootically infected with avian polyomavirus and that the sampled populations are free of Pacheco's disease.     

A feather disease in Senegal doves (Streptopelia senegalensis) morphologically similar to psittacine beak and feather disease.

The pathogenesis and epidemiology of a feather disease in wild Senegal doves (Streptopelia senegalensis) which is morphologically similar to psittacine beak and feather disease (PBFD) was investigated. Although the lesions in doves resembled PBFD there was little evidence for the presence of psittacine circovirus (PsCV). Haemagglutination activity (HA) using type A galah (Eolophus roseicapillus) erythro-cytes was not detected in feathers or livers of affected doves as would occur in PBFD. Low concentrations of HA excreted in the faeces of affected doves was not caused by psittacine circovirus (PsCV) because the antigen in faeces also caused haemagglutination of PsCV-insensitive type B galah erythrocyte and was not inhibited by anti-PsCV antibody. Similar HA of unknown cause was also detected in faeces from clinically normal Senegal doves. Anti-PsCV haemagglutination inhibiting (HI) antibody was not detected in the serum of affected doves or in the blood of 206 clinically normal wild Senegal doves or 17 captive columbid birds in close contact with a flock of psittacine birds that was known to be PsCV-infected. Senegal doves also failed to seroconvert after two inoculations with PsCV purified from the feathers of a PBFD-affected long-billed corella (Cacatua tenuirostris). The results indicate that the feather disease seen in feral Senegal doves in Perth is not due to PsCV although the possibility that it is due to another antigenically distinct circovirus was not eliminated.     

Recombinant expression of a truncated capsid protein of beak and feather disease virus and its application in serological tests.

Beak and feather disease virus (BFDV) causes severe disease characterized by irreversible feather disorders and severe immunosuppression in many psittacine species. BFDV cannot be propagated in tissue or cell cultures, rendering virus propagation and thus diagnosis rather difficult. To develop reliable diagnostic methods, the region encoding the BFDV capsid protein C1 was cloned from an infected sulphur-crested cockatoo (Cacatua galerita). Phylogenetic analysis showed this gene had 76.3 to 83.2% amino acid identity to published sequences. No protein was detected after induction of full-length C1 expression in Escherichia coli. However, deletion of an amino-terminal arginine-rich sequence facilitated expression. C1(39-244)-His, a polyhistidine-tailed variant of this protein, was purified and used for immunization of chickens. The immune sera detected C1 with an apparent molecular weight of 27 kDa in western blots of organ homogenates of BFDV-infected birds. Using C1(39-244)-His as antigen, 11 psittacine sera were tested for the presence of BFDV-specific antibodies by enzyme-linked immunosorbent assay and immunoblotting. The results obtained correlated well with the BFDV-specific haemagglutination inhibition activity of the sera, suggesting C1(39-244)-His has value as a recombinant antigen for BFDV-specific serological tests.     

Comparison of three animal viruses with circular single-stranded DNA genomes

Summary No common antigenic determinants and no DNA sequence homologies were detected when three animal viruses, chicken anaemia agent (CAA), porcine circovirus (PCV), and psittacine beak and feather disease virus (PBFDV), all of which possess circular single-stranded DNA genomes, were compared. Negative contrast electron microscopy showed that PCV and PBFDV particles were 30% smaller than CAA particles and lacked the surface structure of CAA.     

Prevalence and genetic characterization of avian polyomavirus and psittacine beak and feather disease virus isolated from budgerigars in Mainland China

Budgerigar fledgling disease (BFD) and psittacine beak and feather disease (PBFD) are caused by avian polyomavirus (APV) and psittacine beak and feather disease virus (PBFDV), respectively. These diseases frequently infect psittacine birds and result in similar clinical manifestations. In this study, we observed the prevalence of PBFDV infection and a dual infection of APV and PBFDV in a budgerigar (Melopsittacus undulatus) in Mainland China for the first time. One PBFDV isolate and two APV isolates were harvested using chicken embryos. Genetic characterization and phylogenetic analysis of the complete genome of the two APV isolates revealed nucleotide similarity ranging from 99.0% to 99.6% to other sequences in GenBank, and a 14-bp insertion was observed in the genome of one APV isolate. The results of complete genome analysis of the PBFDV isolate showed nucleotide similarity ranging from 83.0% to 95.0% with other PBFDV sequences in GenBank. Genetic characterization and phylogenetic analysis of the APV and PBFDV strains isolated in this study indicated that the isolates from China were closely related to their Japanese counterparts. The results of this study will help to identify molecular determinants and will aid further research on the prevention and control of APV and PBFD infection.     

Hemagglutination by equine infectious anemia virus.

Equine infectious anemia (EIA) virus which was propagated on an equine dermal cell line agglutinated guinea pig erythrocytes. Viral fluids containing about 10(7.5) mean tissue culture infective doses/ml showed hemagglutinating (HA) titers ranging from 16 to 32 units/0.05 ml. Results of cesium chloride equilibrium density gradient centrifugation revealed that the hemagglutinin was inseparable from the virus particles. The hemagglutination reaction persisted over a wide range of temperature and pH, and the absence of divalent cations did not decrease its activity. The HA activity was stable at 4 degrees C but not at 56 degreesC. The activity was destroyed by virus-disrupting lipid solvents and moderately sensitive to a proteolytic enzyme. Neuraminidase enhanced HA activity slightly. Phospholipase C had no effect on HA titer, although it completely inactivated infectivity. It was relatively stable to ultraviolet irradiation. Thus, the hemagglutinin appears to be closely associated with virus particles, and its activity is dependent on the presence of its lipids and proteins. Hemagglutination was inhibited by sera from horses infected with EIA virus. Hemagglutinin receptors on the erythrocytes were inactivated by a proteolytic enzyme and formaldehyde but were not influenced by neuraminidase, sodium deoxycholate, or KIO4.     

Isolation and characterization of a parvovirus of rabbits.

The isolation and characterization of a new virus from rabbit stool are described. The virus replicated in rabbit kidney cell cultures and agglutinated human group O erythrocytes at 4 degrees C. It was stable at acid pH and resistant to chloroform and heat treatment. The growth of the virus was inhibited by 5-iodo-2-deoxyuridine, and virions were stained red with acridine orange, suggesting that they contain single-stranded deoxyribonucleic acid. The density of virions was 1.41 to 1.44 g/ml in CsCl, and the sedimentation value was 137S in sucrose at 4 degrees C. The infectious particles had cubic symmetry and were 27 to 28 nm in diameter by electron microscopy. By these properties this virus can be classified as a member of the parvovirus group. Antibody response was demonstrated in the rabbit from which this virus was recovered. A number of rabbits from a commercial source were found to contain hemagglutination-inhibiting antibody to this virus.     

Hemagglutination with transmissible gastroenteritis virus

Summary Transmissible gastroenteritis virus grown in primary swine kidney cell cultures agglutinated erythrocytes from chicken, guinea pig and cattle but not erythrocytes from mouse and goose. The optimal incubation temperature was at 4°C. The hemagglutination (HA) reaction was inhibited by specific antiserum. Some factors involved in the HA and HA-inhibition (HI) were investigated and standard HA and HI tests were established. HI antibody titers of individual pig sera showed a significant positive correlation with their neutralizing antibody titers.     

Wesselsbron virus haemagglutination: studies with erythrocytes of various animal species at different pH and temperatures

Summary The haemagglutinating (HA) properties of the Nigerian strain of Wesselsbron virus have been investigated using erythrocytes from a wide range of animals. The results showed that Wesselsbron virus possesses HA activity when extracted using the sucrose and acetone method. The erythrocytes of goose, horse, donkey, pig, cattle, sheep, goat, monkey, man, rabbit, rat, guinea pig and chicken were agglutinated by Wesselsbron virus at different pH values (5.75–7.0) and temperatures of 4°C, room (25±2°C) and 37°C.The ability to haemagglutinate fell as pH increased, but the effect of incubation at different temperature was not marked. However, under the conditions of the experiment HA pattern was clearest at 37°C. High HA titres (1:16) were consistently obtained using goose, horse, donkey and human erythrocytes at different temperatures.     

An outbreak of Newcastle disease in a pheasant flock in Iraq

A highly virulent strain of Newcastle disease virus (NDV) was isolated from pheasants in an unvaccinated private imported flock in the Rathwania area near Baghdad, Iraq, which was suffering from ND. The virus was propagated in 9-day-old specific pathogen-free chicken embryos. It was characterised by the following tests: intracerebral pathogenicity index (ICPI), intravenous pathogenicity index (IVPI), mean death time (MDT), haemagglutinin stability at 56 degrees C and mammalian erythrocyte agglutination. The ICPI, IVPI and MDT for the virus were: 1.89, 2.63 and 64 hours respectively. The stability of its haemagglutinin at 56 degrees C was 120 minutes. It agglutinated chicken and pheasant but not bovine, equine and human type "O" erythrocytes.     

Lack of correlation between haemagglutination and adherence to epithelial cells in Yersinia pseudotuberculosis

Yersinia pseudotuberculosis was examined for its haemagglutinating activity and adherence to cultured epithelial cells (HEp-2) in relation to possession of a virulence (VW) plasmid and to growth conditions. VW-lacking (VW-) bacteria were isolated from ten VW+ strains of each serovar which, after they were grown on CFA plates at 37 degrees C, agglutinated the erythrocytes from five different species. In contrast to the bacteria possessing the plasmid (VW+) half of the VW- bacteria, grown on CFA plates at 37 degrees C, did not agglutinate any of the erythrocytes used and the other half agglutinated only human erythrocytes. Furthermore, when grown on CFA plates at 25 degrees C, neither VW+ nor VW- bacteria showed a haemagglutinating activity. When the bacteria were grown in CFA broth, only two strains grown at 25 degrees C did not agglutinate any of the erythrocytes tested. The VW+ and VW- bacteria of the remaining strains, grown either at 25 degrees C or 37 degrees C, showed relatively high haemagglutinating activity. Adherence to HEp-2 cells did not correlate with haemagglutinating activity in Y. pseudotuberculosis; the VW+ bacteria grown at 37 degrees C adhered to HEp-2 cells more efficiently than either the VW- derivatives or the VW+ bacteria grown at 25 degrees C, regardless of the growth medium. These results indicate that some of the haemagglutinins detected on Y. pseudotuberculosis are not involved in the adherence to HEp-2 cells.     

Temperature enhancement of syncytium formation by HIV and Sendai virus.

Syncytium formation, the characteristic cytopathic effect (CPE) of the human immunodeficiency virus (HIV) and cell fusion by Sendai virus, is accelerated by increasing the ambient temperature to values at which normal metabolic activity is inhibited. Uninfected C8166, CEM, and H9 cells were absorbed at 4 degrees C onto monolayers of H9 cells chronically infected with HIV and incubated subsequently at either 37 degrees C or 45 degrees C. Similarly chick and human erythrocytes and Hela cells were agglutinated with Sendai virus at 4 degrees C before incubation at temperatures of up to 50 degrees C. With both viruses the rate of cell fusion was directly related to temperature. Since membrane fluidity is dependent on the phase-transition temperature points of the membrane lipids it is proposed that sufficient membrane fluidity is essential for cell fusion to occur. The implication of these observations on the cytopathology of HIV is discussed.     

Properties of mouse leukemia viruses. IV. Hemagglutination assay and characterization of hemagglutinating surface components

A hemagglutination (HA) assay for mouse leukemia virus (MuLV) concentrates is described. The assay gives linear dose-response data between concentrations of approximately 10¹¹ and 8 × 10¹² particles per milliliter. One HA unit was equivalent to approximately 5 sX 10⁷ virus particles in those preparations where surface projections (knobs) were readily detectable on the virions. When knobs were removed during purification or by bromelain treatment, the HA activity was reduced or eliminated. Bromelain-treated virus also lacked glycoprotein component (s), did not absorb neutralizing MuLV antibody, and was noninfectious. Thus, the HA substructure is clearly a surface component of the virion and has an apparent association with the surface knobs, glycoprotein (s), and type-specific antigens. Treatment with neuraminidase and phospholipase C, as required for demonstration of HA activity, damaged the envelope of the virion but did not release hemagglutinating subunits or surface knobs. Active hemagglutinin recovered from enzyme-treated virus by degradation with Tween 80 and ether and density gradient centrifugation was stable under various physical treatments but was heat sensitive. Active hemagglutinin could also be recovered from non-enzyme-treated virus by similar procedures. Concentrated preparations of avian myeloblastosis virus and feline leukemia virus agglutinated chicken and sheep erythrocytes, respectively, but in both cases the specific HA activities were low and the reactions could not be inhibited by specific antisera.     

Purification and hemagglutinating properties of egg drop syndrome 1976 virus

Summary We purified three populations of virus particles, F7, F9 and F17, with buoyant densities of 1.34, 1.33 and 1.29 g/ml, respectively, in CsCl equilibrium density gradients from cultures of chick embryo liver cells infected with the H-162 strain of the virus of egg drop syndrome 1976. F9 particles were infectious complete virions and most F17 particles were empty particles. F7 particles were less infectious, and had little capacity of hemagglutination (HA). HA titers were the same at 4° and 37° C and maximal between pH 6.4 and 8.4 and ionic strength from 0.14 to 0.54m of NaCl. HA titer was inversely proportional to erythrocyte concentration. Potassium periodate destroyed markedly the infectivity of the virus and partially its HA activity at 37° C. HA activity was stable at 56° C or lower temperatures and destroyed at 80° C. Trypsin, -chymotrypsin, papain, ficin and neuraminidase had no effect on HA activity. Alpha-chymotrypsin destroyed the receptor for the virus on chicken erythrocytes, whereas trypsin and neuraminidase did not affect the receptor.With 2 Figures     

Preparation of noninfectious hepatitis A virus hemagglutinin for detecting hemagglutination inhibition antibodies

Hepatitis A virus (HAV) harvested from infected MRC-5 cells can hemagglutinate various species of erythrocytes at acid pH (Eckels et al., 1989). Further studies revealed that the majority of the hemagglutinin (HA) in MRC-5 and BS-C-1 cells was cell-associated. A simplified procedure for preparing HAV-HA consisted of collecting infected cells in phosphate-buffered saline followed by three cycles of freeze-thawing and sonication. The fluids were clarified and stored at 4 degrees C. The analysis of HA by rate-zonal sucrose gradient centrifugation indicated that the majority of HA co-migrated with infectious virus. Complete inactivation of infectious HAV with 0.03% beta-propiolactone (BPL) did not affect HA activity, while inactivation with 0.05% formalin caused a 16-fold reduction in titer. There was no difference in HAI antibody titers when BPL-treated HA was compared to untreated HA in the hemagglutination inhibition (HAI) test.     

Polyuria and polydipsia due to vitamin and mineral oversupplementation of the diet of a salmon crested cockatoo (Cacatua moluccensis) and a blue and gold macaw (Ara ararauna).

This paper describes a salmon-crested cockatoo (Cacatua moluccensis) and a blue and gold macaw (Ara ararauna) of one owner, both presented with polyuria/polydipsia and weight loss. A tentative diagnosis of hypervitaminosis D(3) was based on the condition of hypercalcaemia, radiological findings and dietary history. On postmortem examination of the cockatoo, metastatic calcifications in the kidneys, lungs and proventriculus were seen. The diet was found to be oversupplemented with vitamin and mineral mixtures. The dietary concentrations of vitamins D(3) and A were over 20-fold higher than the recommended levels. The diet also contained more calcium than is recommended. Although macaws are considered to be more susceptible to hypervitaminosis D(3) than other psittacines, the cockatoo had more severe signs and died.     

Hemagglutination with pseudorabies virus

Summary Pseudorabies virus grown in CPK cell cultures was tested for hemagglutination (HA) with erythrocytes of a variety of species at 4°C, 25°C and 37°C. HA was observed at all temperatures with mouse erythrocytes but not with cattle, sheep, goat, swine, cat, rabbit, guinea pig, rat, mongolian gerbil, chicken, and goose erythrocytes. Mice showed a strain variation in agglutinability of their erythrocytes, requiring selection of mice to obtain erythrocytes for HA. The HA reaction was inhibited by specific antiserum. Some factors involved in the HA and HA-inhibition (HI) were investigated and standard HA and HI tests were established. HI antibody titers of individual pig sera showed a significant positive correlation with their neutralizing antibody titers.     

Mutation of the HANA protein of Sendai virus by passage in eggs.

A study was made to elucidate the effect of host cells on the HANA protein of Sendai virus. Two strains of Sendai virus were isolated from an epidemic in an animal laboratory by inoculating the lung homogenate of a moribund mouse either into LLC-MK2 cells (Oh-L) or into the allantoic cavity of embryonated eggs (Oh-E). Oh-E agglutinated chicken red blood cells at 37 degrees (HA37+), while Oh-L did not (HA37-). When Oh-L was passaged in eggs, conversion of the HA37- virus to the HA37+ virus readily occurred. A single point mutation was recognized on the HANA protein of the HA37+ virus either at position 525 (Gln----Arg) or at position 198 (Leu----Phe). Hl test with monoclonal antibody revealed conformational changes around the receptor binding site. Neuraminidase activity was also affected by these mutations. The changes in these biological activities of the HANA protein seemed to allow the HA37+ virus to replicate in eggs. On the contrary, the HA37+ virus replicates as efficiently as the HA37- virus in LLC-MK2 cells and no reversion to the HA37- virus was observed. The overall results indicate that the passage of Sendai virus in eggs resulted in selection of viruses possessing a specific mutation on the HANA protein. The pneumopathogenicity in mice was not significantly different between the HA37- virus and the HA37+ virus, suggesting the existence of genes other than the HANA gene that determine mouse pathogenicity.     

Hemagglutination with avian infectious laryngotracheitis virus

Summary Avian infectious laryngotracheitis virus grown in primary chicken kidney cell cultures was tested for hemagglutination (HA) with erythrocytes of a variety of species at 4°C, 22°C, and 37°C. HA was observed at all temperatures with mouse erythrocytes but not with cattle, sheep, goat, swine, rabbit, guinea pig, chicken, and goose erythrocytes. A strain variation between mice in the agglutinability of their erythrocytes necessitated selection of mice to obtain erythrocytes. The HA reaction was inhibited by specific antiserum. Some factors involved in the HA and HA-inhibition (HI) were investigated and standard HA and HI tests were established. HI antibody titers of individual chicken sera had a significant positive correlation with their neutralizing antibody titers.     

Integration of herpes simplex virus type 1 DNA into the DNA of growth-arrested BHK-21 cells.

The ability of HSV-1 DNA to become associated with host cell DNA in an alkaline-stable form has been demonstrated following infection of a ts baby hamster kidney growth mutant (ts BTN-1), at the non-permissive temperature (39.5 depgrees C). After 8 h pre-incubation at 39.5 degrees C, ts BTN-1 cells infected at this temperature using m.o.i. ranging from 0.5 to 200 p.f.u./cell fail to replicate virus DNA even though transport of input virus genomes to the nucleus is the same at both permissive and non-permissive temperatures. Virions containing 3H-labelled DNA were used to infect ts BTN-1 cells at 39.5 degrees C, and the total cellular DNA isolated from these cells was resolved into host and virus material by repeated CsCl equilibrium gradient centrifugation. A significant amount of the input radioactivity was found as a distinct band in the host region in both neutral and alkaline CsCl gradients, strongly suggesting a covalent association between host and virus DNAs. Evidence for this association was strengthened by demonstrating that radioactive material (virus DNA) banding in the host region of CsCl gradients could be driven towards the density expected for virus DNA following degradation of the putative hybrid molecules by shearing.