A comparative evaluation of serum biochemistry profile and antigenic relatedness among velogenic and mesogenic Avian avulavirus 1 infection in chickens and pigeons

Newcastle disease (ND), caused by virulent Avian avulavirus 1 (AAvV 1), affects variety of avian species around the globe. Several AAvV 1 viruses of different genotypes have recently emerged with varying clinical impacts on their susceptible hosts. Although experimental infection with velogenic and mesogenic strains in chickens and pigeons is well-studied, nevertheless, there exists a paucity of data for comparative variations in serum biochemistry profile of susceptible hosts upon challenge with isolates of varying pathogenicities. With this background, a comparative assessment of a range of serum biochemical parameters was made following challenge with duck-originated velogenic strain (sub-genotype VIIi; MF437287) and pigeon-originated mesogenic strain (sub-genotype VIm; KU885949) in chickens and pigeons. For each of the isolate, commercial broiler chickens and wild pigeons were challenged (10^-6.51 EID₅₀/0.1 mL for sub-genotype VIIi and 10^-6.87 EID₅₀/0.1 mL sub-genotype Vim) separately via intranasal and intraocular route. Sera were collected on 0, 3rd, 5th, 7th, and 9th day post-infection (dpi), and processed for quantitative analysis of different biochemical parameters. By day 3 post-infection (pi), a substantial decrease (p < 0.0001) in serum alkaline phosphatase (ALP) was observed in chickens and pigeons challenged with velogenic isolate. On the other hand, from day 5 pi and onward, a significant increase (p < 0.001) in serum ALP and total protein concentration was observed exclusively in pigeons challenged with mesogenic isolate. For serum aspartate aminotransferase (AST), a significant increase (p < 0.05) in concentration was observed on day 3 pi which decreased from day 5 pi and onward in pigeons and chickens challenged with mesogenic isolate. Also, to reveal antigenic differences among homologous and heterologous vaccine and field-prevalent strains, cross-hemagglutination inhibition assay demonstrated antigenically diverse nature (R-value < 0.5) of both strains from vaccine strain (LaSota, genotype II). The study concludes antigenic differences among prevalent genotypes than vaccine strain and, although requires further studies to ascertain study outcomes, the serum biochemical profile may facilitate presumptive diagnosis of disease in their susceptible hosts.

[Comparative research into sensitivity and specificity of immune-enzyme analysis with chemiluminescence and colorimetric detection for detecting antigens and antibodies to avian influenza viruses and newcastle disease]

The goal of this work was to demonstrate the results of the development of the enzyme-linked immunosorbent tests with chemiluminescence detection and colorimetric detection of specific viral antigens and antibodies for identifying the avian influenza and the Newcastle disease viruses: high sensitivity and specificity of the immuno- chemiluminescence assay, which are 10-50 times higher than those of the ELISA colorimetric method. The high effectiveness of the results and the automation of the process of laboratory testing (using a luminometer) allow these methods to be recommended for including in primary screening tests for these infectious diseases.

Immunomodulatory and hepatoprotective role of feed-added Berberis lycium in broiler chicks

BACKGROUND

A large number of plants and their isolates have been shown to potentiate immunity. Some plants exert anti-inflammatory and anti-stress effects, others hepatoprotective activity. In this study, 320 1-day-old broiler chicks were randomly divided into four major groups A, B, C and D and fed rations supplemented with 0, 15, 20 and 22.5 g Berberis lycium kg⁻¹ ration respectively. Each group was further divided into two subgroups, one vaccinated against Newcastle disease (ND) and infectious bursal disease (IBD), the other non-vaccinated. Antibody titre against IBD and ND, relative weight of lymphoid organs, post-challenge morbidity and mortality, serum hepatic enzymes and total serum protein were observed.

RESULTS

Group C had higher anti-IBD and anti-ND antibody titres. Relative bursa weight in groups C and D was higher until day 28, but birds in group C performed better at later stages of examination. Relative spleen weight was highest in group C. During initial stages there was no effect on relative thymus weight, but at later stages the effect was significant. Groups C and D performed similarly in terms of relative thymus weight. The birds were challenged to field IBD through intramuscular injection at a dose rate of 0.5 mL per bird. Post-challenge morbidity was lowest in groups C and D, while treatment significantly (P < 0.001) affected mortality amongst affected (morbid) birds. Levels of serum alanine aminotransferase and alkaline phosphatase were lowest in group C. Serum protein was similar in all groups and in both vaccinated and non-vaccinated broiler chicks.

CONCLUSION

Berberis lycium added to feed at 20 g kg⁻¹ is effective in improving immunity against ND and IBD as well as liver function in broiler chicks.

Combined exposure to cyanobacterial biomass, lead and the Newcastle virus enhances avian toxicity

Under environmental conditions, wild birds can be exposed to multiple stressors including natural toxins, anthropogenic pollutants and infectious agents at the same time. This experimental study was successful in testing the hypothesis that adverse effects of cyanotoxins, heavy metals and a non-pathogenic immunological challenge combine to enhance avian toxicity. Mortality occurred in combined exposures to naturally occurring cyanobacterial biomass and lead shots, lead shots and Newcastle vaccination as well as in single lead shot exposure. Mostly acute effects around day 10 were observed. On day 30 of exposure, there were no differences in the liver accumulation of lead in single and combined exposure groups. Interestingly, liver microcystin levels were elevated in birds co-exposed to cyanobacterial biomass together with lead or lead and the Newcastle virus. Significant differences in body weights between all Pb-exposed and Pb-non-exposed birds were found on days 10 and 20. Single exposure to cyanobacterial biomass resulted in hepatic vacuolar dystrophy, whereas co-exposure with lead led to more severe granular dystrophy. Haematological changes were associated with lead exposure, in particular. Biochemical analysis revealed a decrease in glucose and an increase in lactate dehydrogenase in single and combined cyanobacterial and lead exposures, which also showed a decreased antibody response to vaccination. The combined exposure of experimental birds to sub-lethal doses of individual stressors is ecologically realistic. It brings together new pieces of knowledge on avian health. In light of this study, investigators of wild bird die-offs should be circumspect when evaluating findings of low concentrations of contaminants that would not result in mortality on a separate basis. As such it has implications for wildlife biologists, veterinarians and conservationists of avian biodiversity.

Maternal antibody transfer from dams to their egg yolks, egg whites, and chicks in meat lines of chickens

Maternal antibodies are transferred from hens to the chicks via the egg. To gain insight into maternal antibody transfer and endogenous production of antibodies in broiler chicks, total IgY, IgA, IgM, as well as anti-Newcastle disease virus (NDV) and anti-infectious bronchitis (IBV) antibody levels were examined in the dams' plasma, egg yolks, egg whites, and chicks' plasma on d 3, 7, 14, and 21. Blood was collected from 39-wk-old breeder hens (line 1, n = 17; line 2, n = 21). Fertile eggs were used for antibody extraction from the egg yolks and egg whites (4 to 5 eggs/dam) and for hatching. Unvaccinated chicks (4 to 5 chicks/dam) were reared in a HEPA-filtered room and were bled on d 3, 7, 14 and 21. Based on ELISA methods, plasma levels of IgY and IgM were higher (P < 0.0001), and those of IgA were similar (P = 0.31), in line 2 compared with line 1. Egg yolk IgY and IgA, as well as egg white IgY, IgA, and IgM levels were higher in line 2 compared with line 1 (P < 0.0001). Independent of line of chicken, the percentage dam-to-chick (3 d) plasma transfer of IgY was estimated to be approximately 30%, with that for IgM and IgA less than 1%. Chicks synthesized IgM first, followed by IgA and IgY. Anti-NDV and anti-IBV antibodies were detected in the dams' plasma, egg yolks, and in the chicks' plasma on d 3 and 7, with line 2 having higher anti-IBV and lower anti-NDV levels than line 1 in all samples (P < 0.0001). In summary, IgY levels, total or antigen-specific, in the dams' plasma or eggs were found to be a direct indicator of maternal antibody transfer to the chicks' circulation, with an expected percentage transfer of approximately 30%. This knowledge, together with the observed time course of endogenous antibody production in broiler chicks, may find direct application in formulating strategies for protecting chicks, especially during the first few weeks of age when their immune system is not yet fully functional.

Newcastle disease virus (strain Herts 33/56) in tissues and organs of chickens infected experimentally

Six-week-old susceptible specific pathogen free chickens were infected intranasally with the virulent Newcastle disease virus strain Herts 33/56 and the levels of virus present in blood, faeces, breast muscle, leg muscle and a pool of heart/kidney/spleen were estimated in birds killed humanely at each day post inoculation. Highest titres were recorded at day 4 post inoculation when titres of virus were 10(6) median egg infectious doses (EID50)/g in the heart/kidney/spleen pool, 10(4.2) EID50/g in the leg muscle and 10(4) EID50/g in the breast muscle and faeces. A median oral infectious dose of Newcastle disease virus strain Herts 33/56 for 3-week-old chickens was estimated to be equivalent to 10(4) EID50.

Unexpected newcastle disease virus in day old commercial chicks and breeder hen

Newcastle disease virus (NDV) specific antigen in the gut contents and NDV specific antibody in blood circulation were seen in day old chicks belonging to nine different commercial hatcheries of Tamil Nadu, India. Antigen disappeared by 4th week and antibody by 6th week of age. Fourteen NDV isolates obtained from the gut contents of day old chicks of different commercial hatcheries, one NDV isolate from dead in shell eggs and one NDV isolate from breeder hen were characterized and grouped under velogenic, mesogenic and lentogenic pathotypes. Four isolates were grouped under F and another four isolates were grouped under E based on reaction with monoclonal antibodies (Mabs) but found to be velogenic based on pathogenicity tests. In one particular flock velogenie NDV was isolated from breeder hen, dead in shell embryos and day old chicks and they all belong to Mabs group E. Vertical transmission of velogenic, mesogenic and lentogenic NDVs and role of NDVs in the gut contents have been discussed.

Rapid serological profiling by an immunocomb-based dot-enzyme-linked immunosorbent test for three major poultry diseases

An immunocomb-based dot-ELISA, employing specially designed apparatus, was used to measure the antibody status for the three major poultry diseases--Newcastle disease, infectious bursal disease and infectious bronchitis--in single test sera. Positive samples could be classified into strong, moderate and weak positives by comparison with the colour reaction given by known strong and weak positive serum controls. The simultaneous dot-immunobinding assay gave reproducible results and allowed considerable savings on the cost of reagents compared to liquid ELISA. The antigen-coated immunocomb can be stored under refrigeration and the test can be performed rapidly under field conditions by trained personnel.

Diseases of free-ranging chickens in the Qwa-Qwa District of the northeastern Free State province of South Africa

A total of 177 free-ranging chickens from 19 Qwa-Qwa villages were bled from wing veins over a period of 6 months (June-November 2000). Serological tests indicated that 5% of chickens tested had been exposed to Newcastle disease, 43% to infectious bronchitis and 63% to Mycoplasma gallisepticum infection. McMaster and Visser sieve techniques were used to determine helminth and coccidia from pooled fresh faecal samples. Helminths isolated in 37% of the villages investigated were Heterakis, Ascaridia and Capillaria species. Eimeria species were also isolated in 32% of the villages investigated. The red fowl mite (Dermanyssus gallinae) was isolated from some of the birds and their nests. Data from a questionnaire survey indicated that all farmers interviewed had never received any technical support and that their chickens had never been vaccinated against any avian diseases. Only 10.5% of the owners interviewed had scientific knowledge on poultry diseases. There is an urgent need for the government to support free-ranging poultry farmers by providing subsidised vaccinations and technical support in order to develop and stimulate economic development in impoverished rural areas of South Africa.

Immunoglobulin class distribution of systemic and mucosal antibody responses to Newcastle disease in chickens

In serum, tracheal wash fluid, and bile from chickens that were inoculated with live or inactivated Newcastle disease virus (NDV), the kinetics and immunoglobulin (Ig) class distribution of an antibody response were demonstrated. The Ig classes (IgM, IgG, and IgA) were captured using monoclonal antibodies (MAbs) in enzyme-linked immunosorbent assays (Ig-capture ELISA). The antibody specificity of the captured Ig was confirmed by binding of NDV. After inoculation with live virus, antibodies of the IgG and IgM classes were mainly found in serum. IgM was produced early from day 4 postexposure (PE) onward, IgG was detected later from day 7 PE onward, and in the tracheal wash fluid and bile, all three Ig classes were demonstrated. After inoculation of inactivated virus, a delayed response of all three classes was observed in serum, and only IgM and IgG were recognized in the tracheal fluid and bile. The type of vaccine and the mute of antigen entrance may have determined the immunoglobulin class produced. The Ig-capture ELISA assay developed in this study can be useful for evaluating various strategies to improve the efficacy of Newcastle disease vaccines and to study the evoked immune mechanisms.

A novel transcutaneous plasmid-dimethylsulfoxide delivery technique for avian nucleic acid immunization

In this report, we show that dimethylsulfoxide (DMSO) enhances liposome-mediated transfection of nucleic acid in chicken macrophage cells and that this could be exploited for the transcutaneous delivery of naked DNA through the intact skin of chickens. We found that DMSO enhanced transfection efficiencies of lipofectamine and polyethyleneimine in HD-11 chicken macrophage cells. Based on this principle, we showed that transcutaneous delivery of a DNA plasmid-dimethylsulfoxide mixture (1:1) to untreated skin of chickens results in a wide distribution of the plasmid in the body. Distribution studies were done using plasmids encoding enhanced green fluorescent protein (EGFP) reporter gene and a bivalent DNA vaccine coding for infectious bursal disease virus (IBDV) and Newcastle disease virus (NDV) immunogenic protein genes. This bivalent vaccine induced mucosal and systemic immune responses, as evidenced by IgA and IgM production in the tears and serum of vaccinated chickens. Mucosal immune responses in the tears after topical vaccination were significantly higher (P < 0.05) than after i.m. delivery of the same DNA vaccine and were characterized by the absence of an IgG response. The biodistribution of plasmid indicated that topical delivery with DMSO resulted in a wide distribution and persistence of the plasmid until 15 weeks post-primary vaccination. Both delivery methods resulted in insert-specific message being made in several body tissues, but after topical delivery the virus-specific mRNA could be detected in the bone marrow of one out of three chickens until 15 weeks post-primary vaccination. Furthermore, transcutaneous delivery of this DNA vaccine using DMSO conferred protection from challenge with virulent IBDV (86% survival) and NDV (86% survival). This novel transcutaneous method of delivery of a DNA vaccine shows promise as being an easy and effective way to deliver nucleic acids through intact skin for vaccination or therapeutic purposes.

Serosurvey for Newcastle disease and avian influenza A virus antibodies in great cormorants from France

Inland great cormorants (Phalacrocorax carbo) culled in France were examined in the winter of 1997-98 and 1998-99 for antibodies to Newcastle disease (ND) and influenza A strains H5 and H7 by the hemagglutination inhibition test. Antibodies to influenza A group antigen were tested by agar gel precipitin test. Ten of 53 adult individuals were seropositive for ND virus. All sera were negative for influenza A antibodies. It is speculated that ND occurred in the sampled population.

Newcastle disease virus in double-crested cormorants in Alabama, Florida, and Mississippi

In order to understand the epidemiology of Newcastle disease (ND) outbreaks in double-crested cormorants (Phalacrocorax auritus), a study was conducted on wintering migratory cormorants (P. a. auritus) in Alabama and Mississippi (USA) and non-migratory cormorants (P. a. floridanus) that breed in Florida (USA). Antibodies against ND virus were detected by the hemagglutination-inhibition method in sera from 86 of 183 (47%) migratory cormorants over-wintering in eight roosting sites in Alabama and Mississippi between November, 1997 and April, 1999. Titers ranged from 5 to 40. Antibody prevalences in sera collected from females in early winter (November and December) (26%) and late winter (February and March) (56%) were significantly different (P = 0.0007). None of 45 serum samples from 1- to 7-wk-old nestlings from 11 colonies in Florida during the 1997-98 and 1998-99 breeding seasons was positive. However, antibodies were detected in yolk samples from 98 of 126 (78%) eggs collected in these same colonies. Titers ranged from 4 to 256. The prevalence of antibodies in eggs collected from fresh-water colonies (63% prevalence, n = 30) and salt-water colonies (82% prevalence, n = 96) was significantly different (P = 0.041). ND virus was not isolated from tissues of 18 cormorants and cloacal and tracheal swabs from 202 cormorants collected in Alabama and Mississippi; virus was also not isolated from cloacal and tracheal swabs from 51 nestlings from Florida.

The interaction between Newcastle disease virus and Escherichia coli endotoxin in chickens

The interaction between Newcastle disease virus (NDV) and Escherichia coli endotoxin was studied in cell cultures, embryonated chicken eggs, and 8-wk-old chickens. These interactions were evaluated according to the induction of specific or nonspecific resistance in the host system and the virus titer produced in both chicken embryos and chickens. The endotoxin of E. coli induced a decrease in the size of the bursa of Fabricius in live chickens. Escherichia coli endotoxin given intravenously induced plasma antiviral activity in chickens that was interpreted to be interferon, as detected in a vesicular stomatitis virus plaque reduction assay. Endotoxin failed to produced toxic effects in the chicken embryo fibroblasts (CEFs) or to result in any antiviral effect because no change was noted in the number of NDV plaques formed in CEF cultures. When endotoxin was given 3 days before NDV exposure in chickens, the virus titers were significantly (P < 0.05) decreased from a peak of 10(2) to 10(0.18), 10(2.5) to 10(0.18), and 10(2.5) to 0 in the spleens, lungs, and kidneys, respectively, at 72 hr post-NDV inoculation. When endotoxin was given 24 hr after NDV inoculation, the NDV titer significantly (P < 0.05) increased from 10(2.0) to 10(3.5), 10(2.5) to 10(6.5), 10(2.5) to 10(4.5), 0 to 10(2.5) in the spleen, lungs, kidneys, and liver, respectively, at 72 hr after NDV inoculation. In chicken sera, hemagglutination inhibition (HI) titer to NDV was significantly (P < 0.05) enhanced from 1164 to 3127 when endotoxin was given prior to virus inoculation. However, there was a decrease in HI to NDV from 1164 to 727 without a significant difference in chicken sera when NDV was given prior to endotoxin inoculation.

Antigenetically unusual Newcastle disease virus from racing pigeons in India

Newcastle disease virus isolated from an outbreak in racing pigeons in India was found to be velogenic, based on the mean time to death in 10-day-old embryonated hen's eggs, the intravenous pathogenicity index in 6-week-old chickens and the pathogenesis in chickens and pigeons. The virus induced disease in chickens without prior adaptation in chickens. The virus was antigenically unusual since it could not be grouped with the available panel of monoclonal antibodies at the World Reference Laboratory for Newcastle disease, UK. However, commercially available lentogenic and mesogenic vaccines provided 100% protection to chickens against this antigenically unusual NDV.

A survey of Newcastle disease in Swiss laying-hen flocks using serological testing and simulation modelling

Newcastle disease (ND) is a highly contagious viral disease of birds particularly domestic poultry. Switzerland is currently declared free from ND; since vaccination is prohibited, the detection of antibodies against ND virus (NDV) results in the destruction of the respective flock (stamping-out policy). However, in 1995 and 1996, antibody-positive flocks were detected and sporadic ND outbreaks even occurred in Switzerland. Therefore, a serosurvey was done to look for evidence of NDV infections in Swiss laying-hen flocks. The survey was designed to provide 95% confidence of detecting at least one seropositive flock if the flock prevalence were 1%. Thirty blood samples from each of 260 commercial laying-hen flocks were collected during 1996 in a central poultry slaughterhouse. Sera were screened for NDV antibodies with a commercial blocking enzyme-linked immunosorbent assay (ELISA). Samples with a questionable or positive test result were retested with the same ELISA. A stochastic computer model was applied to define a cut-off number of test-positive samples to help to differentiate between true- and false-positive flocks and to estimate the true flock prevalence of infection. Four flocks were identified as NDV-seropositive and the NDV true seroprevalence among commercial laying-hen flocks in Switzerland was most likely between 1.35 and 1.55%. This indicates that Swiss laying-hen and parental flocks with more than 150 animals have been in contact with strains of NDV that cause subclinical infection in chicken, because no clinical symptoms have been observed. In this context, computer simulation was a useful technique to interpret survey results.

A dot immunoblotting assay (dot blot ELISA) for early detection of Newcastle disease antibodies in chickens

An enzyme-linked immunosorbent assay using nitrocellulose blotting membrane (dot blot ELISA) was developed for the detection of antibodies against Newcastle disease virus (NDV) in chickens. In this method, a nitrocellulose blotting membrane was used as the solid phase carrier. NDV antigens were directly bound onto the nitrocellulose membrane that was set into a dot blot microfiltration apparatus. Efficiency of the assay was evaluated using known positive and negative NDV sera obtained from chickens. The ability of the assay to detect antibodies 2 days earlier than the standard hemagglutination-inhibition (HI) test was demonstrated on sera collected from chickens experimentally infected with NDV, La Sota strain.

Detection of antibodies to Newcastle disease virus in ostriches (Struthio camelus) by an indirect ELISA

A two-graph receiver operating characteristic analysis, performed on the hemagglutination-inhibition (HI) and enzyme-linked immunosorbent assay (ELISA) test results of a Newcastle disease virus (NDV)-positive and NDV-negative control group of ostrich sera, proved that the ELISA was superior to the HI in both sensitivity and specificity. Comparison of results of the two assays performed on a panel of simulated positive sera ranging from very weak to very strong showed that the ELISA was at least 10 times more sensitive than the HI in detecting low levels of ostrich antibodies to NDV. The ELISA also has the advantage of using untreated serum in a single dilution as opposed to the HI test, which uses pretreated serum in titration.

Postvaccinal immune response to regimens of Newcastle disease vaccination by filter paper sampling technique

Seven hundred and ten blood samples were collected at random from commercial layers in Tamil Nadu on Whatman filter paper No. 1 instead of the conventional method of serum collection. The birds were subjected to different Newcastle disease (ND) vaccination schedules and samples were collected to study the vaccinal response to ND at field level. Eluates were obtained from sample areas of filter paper using Brij-35 solution [detergent] and subjected to the micro haemagglutination inhibition (HI) test for ND antibodies. The HI titre ranged from less than 2(4) to 2(9). The possible causes of poor immune response to ND vaccinations are discussed.

Efficacy of a recombinant fowl pox-based Newcastle disease virus vaccine candidate against velogenic and respiratory challenge

A fowl pox-based recombinant virus TROVAC-NDV (vFP96.5) was developed expressing the fusion and hemagglutinin-neuraminidase glycoproteins from a velogenic strain of Newcastle disease virus (NDV). Studies in specific-pathogen-free birds indicated that inoculation of a single dose of the recombinant led to the induction of significant levels of hemagglutination-inhibiting antibody that were maintained to 8 wk postinoculation. Further, the recombinant induced protective immunity against a combined intramuscular velogenic NDV challenge and respiratory NDV challenge. In commercial broiler chickens that were inoculated in the presence of maternally derived NDV immunity, the level of the NDV-specific humoral response was dampened, but significant levels of protection against both a lethal intramuscular NDV challenge and a fowl poxvirus challenge were obtained.

Efficacy of experimental animal and vegetable oil-emulsion vaccines for Newcastle disease and avian influenza

Acceptable oil-emulsion vaccines were sought to replace mineral oil-emulsion vaccines that, by regulations, require a 42-day minimum holding period for poultry between injection and slaughter for consumption. Water-in-oil emulsions were prepared using animal or vegetable oils in a ratio of 4 parts oil to 1 part Newcastle disease or avian influenza aqueous antigen. Beeswax particles suspended in the oil at the 5% or 10% level (wt:vol) served as the oil-phase surfactant. Hemagglutination-inhibition titers induced by mineral-oil vaccines were not significantly different from those induced by the most efficacious formulations prepared from animal and vegetable oils. Tissue reaction from injection of animal- and vegetable-oil vaccines was less than that induced by mineral-oil vaccines. An inactivated avian influenza vaccine formulated from peanut oil induced protection against morbidity and death when vaccinated chickens were challenged with a virulent isolate of avian influenza virus.

Effect of vitamin A deficiency and Newcastle disease virus infection on IgA and IgM secretion in chickens

The effect of vitamin A deficiency or the lentogenic La Sota strain of Newcastle disease virus (NDV) infection, or both, on immunoglobulin (IgA and IgM) levels in bile and plasma were investigated. In addition, tissue distribution of IgA-, IgG- and IgM-containing cells was studied to establish the source of these Ig. Chickens (1-d-old) with limited vitamin A reserves were fed ad lib. on diets containing either marginal or adequate levels of vitamin A. At 4 weeks of age, half the chickens in each group were infected with NDV. The number of IgA- and IgM-containing cells was not significantly affected by vitamin A deficiency, demonstrating that neither class-switching nor homing of Ig-containing cells is influenced by vitamin A deficiency. Although bile IgM levels were not significantly different in vitamin A-deficient chickens compared with normal chickens, IgA levels were significantly lower. This decrease was even more pronounced in deficient NDV-infected chickens, despite the higher number of IgA-containing cells found in these birds. These results, together with the slightly increased levels of IgA in plasma of vitamin A-deficient chickens, suggest that the hepatobiliary transport of IgA is impaired by vitamin A deficiency and possibly also by NDV infection, although disturbed secretion by IgA-containing cells cannot be excluded.

Effects of Newcastle disease virus administration to mice on the metabolism of cerebral biogenic amines, plasma corticosterone, and lymphocyte proliferation

Newcastle disease virus (NDV) administration to mice increased concentrations of plasma corticosterone, with a maximal effect at 8 h. This elevation of plasma corticosterone concentrations was not observed in hypophysectomized animals in which the completeness of the hypophysectomy was verified by functional tests. NDV administration consistently increased concentrations of free tryptophan in all brain regions examined (prefrontal cortex, hypothalamus, and brain stem). It also caused an activation of cerebral catecholamine and indoleamine metabolism as determined by measurement of the amines and their catabolites. 3-Methoxy,4-hydroxyphenylethyleneglycol (MHPG), the major catabolite of norepinephrine (NE), homovanillic acid (HVA), a major catabolite of dopamine (DA), and 5-hydroxyindoleacetic acid (5-HIAA), the major catabolite of serotonin (5-HT), were all increased in both hypothalamus and brain stem. Ratios of catabolites to the parent amine, considered to be an index of utilization of the neurotransmitters, were increased for NE, DA, and 5-HT in the hypothalamus and for DA and 5-HT in the brain stem. This pattern of changes resembles that observed following stressors such as footshock or restraint. There were also significant increases of tryptophan, HVA, dihydroxyphenylacetic acid (DOPAC), and 5-HIAA in hypophysectomized relative to sham-operated mice. The NDV treatment also increased thymus weights and markedly decreased the proliferative responses of isolated spleen cells to phytohemagglutinin, concanavalin A, pokeweed mitogen, and Escherichia coli lipopolysaccharide. These changes were not caused by increased circulating corticosterone because they were present at equal magnitude in hypophysectomized mice. Thymosin alpha 1 concentrations in the plasma were not altered by NDV or hypophysectomy. These results indicate that administration of NDV to mice can initiate neurochemical and endocrine responses like those observed during stress and can also cause immunosuppression. They are thus consistent with the hypothesis that a virus can be a stressor.

Biochemical changes in fowl serum during infection with strains of Newcastle disease virus of differing virulence. Changes in serum proteins, uric acid, lipids and electrolytes

Chickens aged five to six weeks were inoculated with three strains of Newcastle disease virus of differing pathogenicity. The serum level of the metabolites: total protein, albumin, globulin, uric acid, total lipids, cholesterol and electrolytes: calcium, magnesium, sodium and potassium were determined. The changes in serum levels of metabolites were as follows: velogenic infection was accompanied by decrease in total protein and albumin, reduction of lipids and cholesterol and increase in uric acid. No significant changes were found in the values of these metabolites in the serum of chickens infected with mesogenic strain. Lentogenic strain caused elevation of uric acid and cholesterol. All three strains caused decrease of the level of potassium in serum.

Effect of Newcastle disease on serum copper, zinc, cholesterol, and carotenoid values in the chick

Experimentally induced Newcastle disease virus infection of chicks, with a mortality index of 48%, was accompanied by increased concentrations in serum of copper and cholesterol and decreased concentrations of zinc and total carotenoids. These changes distorted, or were superimposed upon, the rhythmic variability in the normal serum concentrations of each of these moieties. Changing values for copper, zinc, and cholesterol became apparent before any overt signs of disease.