Velogenic Viscerotropic Newcastle Disease Virus Research Articles

Vaccination against Moroccan strains of Newcastle disease virus.

Different vaccination programmes commonly used in Moroccan poultry farms were tested for their capacity to protect chickens against two representative Moroccan strains of velogenic viscerotropic Newcastle disease virus under controlled conditions. All vaccination programmes protected the chickens against mortality and the inactivated vaccine gave the highest antibody titres and the best protection against respiratory symptoms.

Cellular and Humoral Response of in Ovo-Bursectomized Chickens to Experimental Challenge with Velogenic Newcastle Disease Virus

Humorally deficient, in ovo-bursectomized (Bx) and sham-Bx chickens were vaccinated twice, 1 month apart, with Newcastle disease virus (NDV) Roakin strain and challenged with a velogenic viscerotropic NDV strain via the oronasal route. Hemagglutination-inhibition and seroneutralization tests showed that Bx chickens had reduced antibody-mediated immunity to virus infection. In contrast, they had significantly higher cell-mediated immunity (CMI) before challenge, as estimated simultaneously by determination of blastogenic capacity of peripheral blood lymphocytes induced by phytohemagglutinin and by specific antigen stimulation. After virus challenge, there was transitory inhibition of CMI based on marked reductions in levels of stimulation indices, and this impairment in CMI was supported by persistence of virus in Bx chickens for longer periods. Bx chickens resisted challenge, even though antibody titers were well below those considered predictive of resistance to challenge, suggesting that CMI provides a degree of resistance to velogenic NDV.

Failure to Demonstrate Viscerotropic Velogenic Newcastle Disease in Psittacine Birds in the Republic of the Philippines

Birds on the islands of Luzon, Mindanao, and Palawan in the Republic of the Philippines were surveyed for viscerotropic velogenic Newcastle disease (VVND). Virus isolation was attempted on 728 cloacal samples from native and exotic psittacine birds, non-psittacine birds, and domestic chickens and ducks. A VVND virus isolate was obtained from a single domestic chicken that had exhibited ocular discharge and diarrhea 3 days before sampling. All other birds were negative for VVND.

Velogenic Viscerotropic Newcastle Disease Virus Strains in Morocco

Isolates of Newcastle disease virus (NDV) in Morocco were characterized as velogenic. Two isolates were from tracheal swabs taken at a Moroccan live poultry market, and four isolates were from field cases. Infection of 8-week-old chickens showed that these isolates and previously characterized Moroccan isolates were of the viscerotropic pathotype. Based on hemagglutinin thermostability and the capacity to agglutinate equine erythrocytes, the Moroccan velogenic viscerotropic NDV isolates were classified as belonging to at least three distinct strains.

Newcastle disease vaccination in Malaysia: application of oil emulsion vaccine.

An experimental oil emulsion Newcastle disease vaccine was evaluated for its efficacy in broiler chickens. A group of chickens vaccinated at one day old with a live lentogenic Newcastle disease vaccine and subsequently revaccinated at three and eight weeks old with the experimental oil emulsion vaccine showed satisfactory haemagglutination inhibition antibody response which persisted for 18 weeks. Between 90 and 100 per cent of the vaccinated chickens were protected when challenged with the velogenic viscerotropic Newcastle disease virus. Although the vaccinated chickens were protected against clinical disease, virus could be isolated from a number of birds. By day 10 to 12 after challenge all the chickens were free from Newcastle disease infection.

Virus Isolations from Pet Birds Submitted for Importation into the United States

From October 1973 to September 1981, 2,882,111 birds were offered for importation into the United States. All were quarantined for 30 days, and specimens were submitted to the laboratory for virus-isolation studies. Viruses were isolated from specimens from 26.3% (598/2,274) of the quarantined lots of birds. Viscerotropic velogenic Newcastle disease virus (VVNDV) was isolated from 141 lots. Nonviscerotropic velogenic Newcastle disease virus (VNDV) was isolated from six lots. All VVNDV- and VNDV-positive lots were refused entry. The percentage of lots refused entry declined from 31.6% in 1974 to 2.9% in 1981. Mesogenic Newcastle disease virus (NDV) was isolated from three lots, and lentogenic NDV was isolated from 23 lots. Lots positive for mesogenic and lentogenic NDV were allowed to enter the United States. Hemagglutinating (HA) viruses other than NDV were isolated from 24.5% (373/1,521) of the lots imported through privately owned quarantine facilities. Of the 8,563 HA viruses isolated, 1,558 were selected for identification. Forty-six percent were identified as paramyxovirus (PMV)-2, 34% were PMV-3, and 20% were influenza A viruses possessing the hemagglutinin subtypes H3, H4, H7, and H10 and the neuraminidase subtypes N1, N6, N7, and N8. The frequency of PMV-2 and PMV-3 isolations fluctuated from year to year, whereas the frequency of isolations of influenza A viruses decreased from 64% in 1974 to 0.2% in 1981. Viruses that did not agglutinate chicken red blood cells were isolated from 52 lots. Psittacine herpesvirus (Pacheco's disease) was isolated from 25 lots of psittacines. Viruses identified by electron microscopy as reoviruses were isolated from 24 lots.(ABSTRACT TRUNCATED AT 250 WORDS)

Scanning Electron Microscopy of Tracheal Epithelium of Chickens Infected with Velogenic Viscerotropic Newcastle Disease Virus

Ultrastructural changes in the tracheal epithelium of chickens infected intranasally with velogenic viscerotropic Newcastle disease virus were examined by scanning electron microscopy. Hypertrophy of the mucus-secreting, or goblet, cells was the first sign of change, followed by disoriented and deformed cilia, hemorrhage, and hyperplasia of goblet cells accompanied by an increase in mucus. By day 7 postinfection, there was a marked decrease in the number of ciliated cells. Submucosal glands and some collagen fibers were exposed to the surface, an indication of loss of the epithelial cells. Macrophages and cell debris were abundant, and hyperplasia of the basal cells was evident in the later stages of infection, probably in an attempt to regenerate the lost epithelium. However, all chickens died 10 days postinfection, before any further work could be done.

Differentiation of Exotic Strains of Newcastle Disease Virus by Oligonucleotide Fingerprinting

The oligonucleotide fingerprints of five of six strains of velogenic-viscerotropic Newcastle disease (VVND) virus were readily distinguishable, even though the strains could not be differentiated by a series of in vivo and in vitro procedures. Two of the VVND virus strains tested (10333-0 and 8231412) showed marked similarity to the prototype strain (MIL-0). Two of the remaining three strains (80-27489 and 80-28634) had identical oligonucleotide fingerprints, even though they had a different isolation history and exhibited small differences in their virulence for chickens. Fingerprints of the sixth VVND strain, 80-12927, demonstrated some similarities when it was compared with the prototype virus fingerprint, but it was quite different from strains 80-27489, 10333-0 and 8231412.

Comparison of Three Experimental Inactivated Oil-Emulsion Newcastle Disease Vaccines

White Leghorn pullets vaccinated previously with live Newcastle disease virus (NDV) were revaccinated at point-of-lay with 3 experimental oil-emulsion (OE) Newcastle disease vaccines to determine whether immunogenicity of OE vaccines is influenced by emulsion composition differences. The vaccines used were formulated differently but contained equal amounts of inactivated NDV in stable, low-viscosity, water-in-oil emulsions. Serological responses to the vaccines differed (P less than 0.01), but 55 of 56 OE vaccinates remained clinically normal following challenge exposure with viscerotropic velogenic NDV 28 or 44 weeks after revaccination; 4 of 21 nonrevaccinated controls and all of 20 nonvaccinated challenge controls were clinically affected or died.

Characterization of a Newcastle disease virus isolated from a parrot (Psittacus erythracus) in Nigeria.

The characteristics of a Newcastle disease virus isolated from a parrot (Psittacus erythracus) in Nigeria were examined using standard laboratory tests. Minimum lethal dose in embryos was 10(-10), mean death time 44.8 h. The intracerebral and intravenous pathologic indices were 1.65 and 2.42, respectively. The virus was resistant at pH 3 and pH 7.2 and the hemagglutinin was thermostable at 56 C for 120 min. Of 10 mammalian species of erythrocytes examined, those of equine and rat were not agglutinated. The isolate was typed as a velogenic viscerotropic Newcastle disease virus.

Newcastle Disease—Pathogenesis and Diagnosis

The pathogenesis and the gross pathology resulting from infection with viscerotropic velogenic Newcastle disease virus pathotypes, generally are characteristic in a susceptible avian population on ...

Embryonated Eggs Compared with Fragments of Chorioallantois Attached to Egg Shell for Isolation of Newcastle Disease Virus

The feasibility of using fragments of chorioallantois attached to egg shell (C-S) as an alternative to embryonated eggs for isolating Newcastle disease virus (NDV) was assessed. In paired titrations of 6 strains of virus, embryonated eggs detected an average of 6-to-7-fold greater amounts of virus than did C-S fragments. The efficiency of isolation of viscerotropic velogenic NDV from 240 swab samples was 97% in embryonated eggs and 84% in C-S fragments. Sensitivity differences between the 2 host systems were revealed only in tests of samples expected to contain small amounts of virus. These results suggest that C-S fragments can be reliably used in some but not all instances, thereby relieving logistic constraints sometimes associated with the use of embryonated eggs.

Viscerotropic Velogenic Newcastle Disease in Pigeons: Clinical Disease and Immunization

SUMMARY Racing homer pigeons were exposed to viscerotropic velogenic Newcastle disease virus (VVNDV) to further characterize the disease in pigeons. Mortality was 7 of 21 juvenile birds and 1 of 10 adult birds. Virus shedding was detected until 21 days postinoculation in some birds. Pigeons infected experimentally shed VVNDV before the onset of clinical disease and were able to transmit VVNDV to chickens and pigeons by contact exposure. Pigeons were also susceptible to infection with VVNDV by contact exposure to an infected chicken. In experiments in which 3 commercial Newcastle disease virus (NDV) vaccines were used to evaluate several vaccination programs, only 1 of the programs completely prevented morbidity and mortality following VVNDV challenge 6 weeks after the final vaccination. Pigeons in that program were vaccinated with viable vaccine and revaccinated at 6 weeks postvaccination with inactivated oil-emulsion vaccine.

Interactions between Viscerotropic Velogenic Newcastle Disease Virus and Pet Birds of Six Species. II. Viral Evolution through Bird Passage

Following in vivo studies in pet birds of 6 species, 279 Newcastle disease virus (NDV) reisolates were selected for characterization by the embryonated-chicken-egg mean-death-time, plaque-assay, hemagglutination-elution, and hemagglutinin-thermostability techniques. Initially, the 279 isolates were screened by the mean-death-time and plaque-assay techniques, and 5 sequential isolates were chosen for each of 3 budgerigars and 2 parrots for characterization by the other 2 in vitro assays to determine whether the Colorado Psittacine Isolate of viscerotropic velogenic (VV) NDV (COPI-VVNDV) had evolved during passage through pet birds. Nineteen isolates were then selected for chicken back-passage studies. Fifteen of the 19 isolates were chosen for potential avirulence for 8-week-old domestic chickens. The 4 remaining isolates produced large red plaques when assayed and were therefore used as virulent virus controls likely to be VVNDV. Subsequent in vitro characterization of selected back-passage chicken NDV isolates demonstrated little change in the 4 parameters originally evaluated for the pet-bird isolates used for the back-passage studies. Although the psittacine isolate slowly evolved to relatively avirulent strains of NDV by passage in pet birds, reversion did not occur during the chicken back-passage studies.

Interactions between Viscerotropic Velogenic Newcastle Disease Virus and Pet Birds of Six Species. I. Clinical and Serologic Responses, and Viral Excretion

Clinical and serologic responses to a psittacine isolate of viscerotropic velogenic Newcastle disease virus (VVNDV) were evaluated in pet birds of six species: budgerigar, yellow-headed Amazon parrot, halfmoon conure, lesser hill mynah, black-headed nun, canary. The clinical response was most marked in the budgerigars, parrots, and conures, and only minimal in the nuns. Between post-exposure days (PED) 3 and 5 some birds developed ruffled plumage, conjunctivitis, and central nervous system dysfunction: ataxia, wing tremors, paralysis of the extremities, and tremors of the head accompanied by nodding and jerking. Mortality by PED 203 was 55% (29/52) in the halfmoon conures, 22% (23/105) in budgerigars, 29% (12/42) in parrots, and 21% (15/71) in nuns. The only clinical signs in canaries and mynahs were progressive death losses, respectively 25% (33/132) and 21% (10/48). The visceral lesions common in chickens with VVNDV were not observed in these six species. Canaries rapidly eliminated Newcastle disease virus (NDV), whereas it was detected for protracted periods in the oral and cloacal secretions of the other five species (for more than a year in parrots). Serologic evaluation by the hemagglutination-inhibition and neutralization tests also indicated prolonged NDV infections in 5 of the 6 species. The seroconversion rate observed in canaries was minimal (13%).

SIMULATED NATURAL INFECTION OF CHICKENS WITH AUSTRALIAN LENTOGENIC NEWCASTLE DISEASE VIRUS AND SUBSEQUENT CHALLENGE WITH VIRULENT VIRUS

A total of 291 eight-week-old chickens were exposed to chickens infected with either of two Australian lentogenic strains (V4 and AVL NDV-1) of Newcastle disease virus (NDV). At 3 weeks after exposure, all chickens exposed to V4 infected chickens had developed haemagglutination-inhibition (HI) antibody. All chickens exposed to AVL NDV-1 virus infected chickens had developed HI antibody 5 weeks later. This sudden late appearance of HI antibody, to titres higher than those observed with V4 chickens, was explained by V4 virus being introduced to the AVL NDV-1 group of chickens. When groups of these chickens were challenged with Roakin virus (mesogenic NDV) at 3 weeks and Fontana 1083 virus (viscerotropic velogenic NDV) and Texas GB virus (neutrotropic NDV) at 3, 5, 10 and 21 weeks only three chickens developed clinical illness one of which died. These chickens were one AVL NDV-1 chicken contact challenged with Fontana 1083 virus at 3 weeks, one V4 chicken oronasally challenged with Texas GB virus at 5 weeks and one V4 chicken challenged oronasally with Fontana 1083 virus at 10 weeks. Susceptible non-vaccinated chickens died soon after challenge. Challenge by oronasal infection with 10(7.0) ELD50 of virus or contact with susceptible infected chickens enabled virulent virus to be isolated from most chickens and was accompanied by a large anamnestic increase in serum HI antibody.

Response of Congenitally Immune Chicks to Viscerotropic Velogenic Newcastle Disease Virus

Separate groups of chicks of hen hyperimmune to viscerotropic velogenic Newcastle disease virus (VVNDV) were challenge-exposed to VVNDV by intraocular route at 1 day and 34 days old. Their response was evaluated by clinical symptoms, hemagglutination-inhibition (HI) titers, and virus isolations. Chicks exposed at 1 day old excreted VVNDV from the vent for up to 60 days; their active mean HI titers remained low (10-40); and deaths from VVNDV occurred early (5-16 days) and late (28-55 days). Chicks challenge-exposed at 34 days old excreted virus from the vent for 10 days; active HI titers developed quickly and remained high (891-1177); and deaths and signs of VVNDV occurred early (5-13 days).

Methods of Spread of Velogenic Viscerotropic Newcastle Disease Virus in the Southern Californian Epidemic of 1971-1973

Data collected during the velogenic viscerotropic Newcastle disease (VVND) epidemic that occurred in southern California from 1971 to 1973 were analyzed to determine the methods of spread of the disease. Spread between chicken flocks was extensive and due mainly to the movement of live birds and mechanical transport of virus by man, especially by vaccination and poultry service crews. Spread to exotic birds was from contact with infected imported stock. Spread to other species was most probably through contact with infected chickens. Infection persisted in commercial chicken flocks because of intensive vaccination programs, heavy traffic and contact between layer operations, and the maintenance of multi-age flocks. These foci of infection probably led to spread of the disease to areas from which VVND had been eradicated several months before. There was no evidence of significant wind-borne spread of virus between flocks.

Salmonellosis in Canaries

In February, 1974, 4,400 canaries were shipped from Holland to a bird import quarantine station in the United States. Approximately two thousand of these birds died within 3 weeks postentry. Tissues were submitted to Veterinary Services Laboratories (VSL), Ames, Iowa, for examination for exotic disease agents. After the Diagnostic Virology Section, VSL, reported no evidence of velogenic viscerotropic Newcastle disease virus, tissues were submitted to the Diagnostic Bacteriology, Clinical Pathology and Reference Assistance Sections, VSL, for differential diagnosis.

Efficacy of a Commercial Newcastle Vaccine against Velogenic Viscerotropic Newcastle Disease Virus

Effects of parental immunity and method of vaccination were studied in broiler chickens vaccinated with a commercial LaSota vaccine and challenged with the Fontana strain of velogenic viscerotropic Newcastle disease (VVND). Immunity was satisfactory from all methods of vaccination used.