Dispersal of micro-organisms in commercial defeathering systems

1. The extent of cross contamination between carcases and the dispersal of micro-organisms to the environs during defeathering was measured in a commercial processing plant. 2. Defeathering reduced the numbers of a marker organism, a nalidixic acid-resistant strain of Escherichia coli K12, on inoculated carcases but dispersed the organism on to preceding and following carcases. 3. The pattern of microbial dispersal during defeathering was similar for naturally occurring bacteria on the carcase, for example, total aerobic counts and counts of presumptive coliforms, suggesting that the marker organism mimics the natural situation realistically. 4. The majority of feathers, together with micro-organisms, were removed during the first 10 s of the defeathering process, which was completed in 45 s, indicating that control measures to minimise cross contamination would be most effective if applied in the early stages of the process. 5. The method of defeathering used by the machine influenced the pattern of microbial dispersal and the extent of cross contamination to other carcases on the same processing line.

Native-feather degradation by Fervidobacterium islandicum AW-1, a newly isolated keratinase-producing thermophilic anaerobe

A native-feather-degrading thermophilic anaerobe was isolated from a geothermal hot stream in Indonesia. Isolate AW-1, identified as a member of the species Fervidobacterium islandicum, was shown to degrade native feathers (0.8%, w/v) completely at 70 degrees C and pH 7 with a maximum specific growth rate (0.14 h(-1)) in Thermotoga- Fervidobacterium(TF) medium. After 24 h of culture, feather degradation led to an increase in free amino acids such as histidine, cysteine and lysine. Moreover, nutritionally essential amino acids such as tryptophan and methionine, which are rare in feather keratin, were also produced as microbial metabolites. A homomultimeric membrane-bound keratinolytic protease (>200 kDa; 97 kDa subunits) was purified from a cell extract of F. islandicum AW-1. The enzyme exhibited activity toward casein and soluble keratin optimally at 100 degrees C and pH 9, and had a half-life of 90 min at 100 degrees C. The enzyme showed higher specific activity for the keratinous substrates than other proteases and catalyzed the cleavage of peptide bonds more rapidly following the reduction of disulfide bridges in feather keratin by 10 mM dithiothreitol. Therefore, the enzyme from F. islandicum AW-1 is a novel, thermostable keratinolytic serine protease.

Monitoring the hygene of chicken hatcheries in Taiwan during 1999-2001

Microorganism contamination in hatcheries and eggs has a serious impact on the viability and quality of chicks as well as on the overall growth performance of chickens. Microbiological agents are present in the fluff when chicks hatch. Detecting microorganisms in fluff is a convenient method for evaluating the hygienic status in a hatchery. Fluff samples from 31 hatcheries collected over 3 years were tested for the total bacterial count, the presence of Salmonella spp., and fungus to evaluate the hygienic status of hatcheries in Taiwan from 1999 through 2001. The total bacterial score from the fluff samples was calculated and expressed as a bacterial score in a log scale. Most hatcheries had a bacterial count ranged from scale 1 to 3. Among the hatcheries, 13% to 29% were contaminated with Salmonella spp.; and 33% to 73% were contaminated with fungi in different quarters. The third quarter of each year was the most contaminated period (p<0.01). According to the data obtained from the fluff tests, hatcheries keep their hygienic status and supply good quality chicks by cleaning and disinfecting.

Polymerase chain reaction for detection of Mycoplasma gallisepticum in environmental samples

The polymerase chain reaction (PCR) was used to detect Mycoplasma gallisepticum in samples collected from the environment of experimentally or naturally infected poultry. Culture was also used in the experimental infections. Of 160 samples of food, drinking water, feathers, droppings or dust collected during experimental infection, 103 were positive using a M. gallisepticum-specific PCR (MG-PCR) and 68 were positive using a PCR (mycoplasma-PCR) that detects all species of the genera Mycoplasma, Spiroplasma, Acholeplasma and Ureaplasma. Six of these samples were also positive by culture. In environmental samples collected on a depopulated M. gallisepticum-positive turkey farm, three and two out of a total of 12 were positive by mycoplasma-PCR and MG-PCR, respectively. These results indicate the disseminating capacity of this mycoplasma and the possible use of PCR methods for epidemiological analyses and control of farm decontamination before the introduction of new birds.

Sensitivity of ornithophillic fungi to some drugs

The occurrence of ornithophillic fungi and related dermatophytes was evaluated from the poultry farm soil samples. Two test species of Microsporum were tested by 'Spore germination' and 'Disc diffusion method' against the two well known antifungal antibiotics i.e. griseofulvin and mycostatin (polyene antibiotic). The data showed cent percent inhibition of fungal spore germination and increased zone of inhibition at higher doses. The antimicrobial drugs including acetyl salicylic acid, benzoic acid and boric acid were also assessed at different doses against the test organisms. Acetyl salicylic acid and boric acid were found to be toxic at higher doses, while these pathogens seems to be somewhat resistant for benzoic acid. It is suggested that the effective doses of these drugs should also be tried for allergic effects on birds and other animals before commercial use.

Direct polymerase chain reaction detection of Campylobacter spp. in poultry hatchery samples

A rapid, sensitive, and specific polymerase chain reaction (PCR) assay was developed for the direct detection of Campylobacter in environmental samples from hatcheries. PCR, with a set of primers specific for the Campylobacter flaA short variable region (SVR), detected the presence of Campylobacter in both fluff and eggshell samples; however, a determination of whether the organism was living or dead could not be made. Conventional cultural methods detected no Campylobacter from the same samples. An additional benefit of the direct PCR assay is it allows for the production of a product that can be sequenced to provide further epidemiologic information.

Broiler carcass contamination with Campylobacter from feces during defeathering

Three sets of experiments were conducted to explore the increase in recovery of Campylobacter from broiler carcasses after defeathering. In the first set of experiments, live broilers obtained from a commercial processor were transported to a pilot plant, and breast skin was sampled by a sponge wipe method before and after defeathering. One of 120 broiler breast skin samples was positive for Campylobacter before defeathering, and 95 of 120 were positive after defeathering. In the second set of experiments, Campylobacter-free flocks were identified, subjected to feed withdrawal, and transported to the pilot plant. Carcasses were intracloacally inoculated with Campylobacter (10(7) CFU) just prior to entering the scald tank. Breast skin sponge samples were negative for Campylobacter before carcasses entered the picker (0 of 120 samples). After defeathering, 69 of 120 samples were positive for Campylobacter, with an average of log10 2.7 CFU per sample (approximately 30 cm2). The third set of experiments was conducted using Campylobacter-positive broilers obtained at a commercial processing plant and transported live to the pilot plant. Just prior to scalding, the cloacae were plugged with tampons and sutured shut on half of the carcasses. Plugged carcasses were scalded, and breast skin samples taken before and after defeathering were compared with those collected from control broilers from the same flock. Prior to defeathering, 1 of 120 breast skin sponge samples were positive for the control carcasses, and 0 of 120 were positive for the plugged carcasses. After passing through the picker, 120 of 120 control carcasses had positive breast skin sponge samples, with an average of log10 4.2 CFU per sample (approximately 30 cm2). Only 13 of 120 plugged carcasses had detectable numbers of Campylobacter on the breast skin sponge, with an average of log10 2.5 CFU per sample. These data indicate that an increase in the recovery of Campylobacter after defeathering can be related to the escape of contaminated feces from the cloaca during defeathering.

Bacterial inoculum enhances keratin degradation and biofilm formation in poultry compost

Native microbial populations can degrade poultry waste, but the process can be hastened by using feather-degrading bacteria. Strains of Bacillus licheniformis and a Streptomyces sp. isolated from the plumage of wild birds were grown in a liquid basal medium and used to inoculate feathers in compost bioreaction vessels. Control vessels had only basal medium added to the feathers, litter and straw. Temperature, ammonia, carbon and nitrogen were monitored for 4 weeks. Scanning electron microscopy of the feather samples showed more complete keratin-degradation, more structural damage, and earlier microbial biofilm formation on inoculated feathers than on uninoculated feathers. A diverse community of aerobic bacteria and fungi were cultured early, but declined rapidly. Thermophilic B. licheniformis and Streptomyces spp. were abundant throughout. Enteric gram-negative bacteria, (e.g., Salmonella, E. coli) originally found on waste feathers were not recovered after day 4. Vessel temperatures reached 64-71 degrees C within 36 h and stabilized at 50 degrees C. When tumble-mixed at day 14, renewed activity peaked at 59 degrees C and quickly dropped as available carbon was used. Feathers soaked in an inoculum of B. licheniformis and Streptomyces degraded more quickly and more completely than feathers that were not presoaked. Inoculation of feather waste could improve composting of the large volume of feather waste generated every year by poultry farms and processing plants.

Feather keratin hydrolysis by a Vibrio sp. strain kr2

The aim of the study was to characterize feather-degrading bacteria isolated from poultry industry waste. A Vibrio sp. strain kr2 producing a high keratinolytic activity when cultured on native feather-containing broth was isolated. The bacterium grew with an optimum at pH 6.0 and 30 degrees C, where maximum featherdegrading activity was also observed. Keratinase production was similar at both 25 and 30 degrees C, while the maximum concentration of soluble protein was reached at 30 degrees C. Reduction of disulphide bridges was also observed, increasing with cultivation time. The keratinase of strain kr2 was active on azokeratin, azocasein, benzoyl-arginine-p-nitroanilide and Ala-Ala-p-nitroanilide as substrates. The amino acid composition of the feather hydrolysate was determined, presenting similarities with that reported for feather lysate, feather meal and raw feathers. A novel feather-degrading bacterium was isolated and characterized, showing high keratinolytic activity. Complete feather degradation was achieved during cultivation. Strain kr2 shows potential for use for biotechnological processes involving keratin hydrolysis.

Detection of Mycoplasma synoviae in poultry environment samples by culture and polymerase chain reaction

Successful detection of Mycoplasma synoviae (MS) by culture and PCR from samples collected in the environment of experimentally infected chickens and turkeys, or under field conditions, is described. Results showed that in the experimental infection, 10/96 and 46/96 samples of food, drinking water, feathers, droppings or dust were positive by culture and Mycoplasma-PCR. In field conditions, the number of positive results for environmental samples were respectively 7/28 and 17/28. These observations highlight the high disseminating capacities of this mycoplasma and show the usefulness of the PCR method for epidemiological studies.

Campylobacter recovery from external and internal organs of commercial broiler carcass prior to scalding

Campylobacter is a human pathogen commonly found on live broilers and processed carcasses. To plan effective intervention strategies, it would be helpful to know which Campylobacter populations are associated with the external and internal organs of broilers. Six carcasses were collected after exiting the bleed tunnel at a commercial broiler plant on each of three visits (n = 18). Carcasses were placed individually into sterile plastic bags, sealed, and covered with ice for transport to the laboratory. Five locations were sampled aseptically from each carcass: breast feathers (hand picked from the sternal tracts); breast skin, including the sternal tracts; crop; ceca; and colon. Samples included adhering contamination or lumen contents and were covered with phosphate-buffered saline and blended. Serial dilutions were made for examination of Campylobacter, coliform, Escherichia coli, and total aerobic bacterial populations. Average sample weights (grams) were as follows: feathers, 1.5; skin, 6.5; crop, 5.1; ceca, 7.8; and colon, 3.1. Campylobacter populations (mean log10 colony-forming units per gram of sample) found were feathers, 5.4; skin, 3.8; crop, 4.7; ceca, 7.3; and colon, 7.2. Coliform/E. coli populations observed were feathers, 6.4/6.0; skin, 5.3/4.9; crop, 4.3/3.7; ceca, 6.6/6.2; and colon, 5.8/5.3. Total aerobic bacterial populations found were feathers, 7.9; skin, 7.1; crop, 5.8; ceca, 6.8; and colon, 6.4. On a per gram basis, ceca and colon are the internal organs that if ruptured could cause the highest number of Campylobacter to be leaked onto the carcass. The crop also contained more Campylobacter per gram than did the skin, and if compromised may increase the numbers on the surface of the carcass. However, even with no contamination from an internal organ, a substantial population of Campylobacter is already resident on broiler skin as the carcass enters the early stages of processing.

Degradation of chicken feathers by Chrysosporium georgiae

Using a baiting technique, Chrysosporium georgiae was isolated from chicken feathers. Twenty-eight different fungal isolates were evaluated for their ability to produce keratinase enzymes using a keratin-salt agar medium containing either white chicken feathers or a prepared feather keratin suspension (KS). The Chrysosporium species were able to use keratin and grow at different rates. Chrysosporium georgiae completely degraded the added keratin after 9 days of incubation. Degradation of feathers by C. georgiae was affected by several cultural factors. Highest keratinolytic activity occurred after 3 weeks of incubation at 6 and 8 pH at 30 degrees C. Chrysosporium georgiae was able to degrade white chicken feathers, whereas bovine and human hair and sheep wool were not degraded and did not support fungal growth. Addition of 1% glucose to the medium containing keratin improved fungal growth and increased enzyme production. Higher keratin degradation resulted in high SH accumulation and the utilization of the carbohydrate carbon in the medium resulted in high keto-acid accumulation but decreased ammonia accumulation. Supplementation of the keratin-salt medium with minerals such as NH4Cl and MgSO4 slightly increased mycelial growth, but decreased production of extracellular keratinase. Keratinase enzymes were very poorly produced in the absence of keratin, indicating its inducible nature. Analysis of endocellular keratinases in the mycelial homogenate indicated higher activity of intracellular keratinase as compared to the extracellular enzyme in culture filtrates. Chrysosporium georgiae was the most superior for keratinase production among the Chrysosporium species tested in the presence or absence of glucose. It produced more of the intracellular enzymes than the exocellular ones.

Bacterial populations associated with the dirty area of a South African poultry abattoir

Bacterial populations associated with three sample types from the neck region of poultry carcasses in the dirty area of an abattoir were characterized. Sample types before and after scalding were skin only, feathers only, and a skin and feather combination. The neck skin of carcasses after the defeathering processing stage was also sampled. Bacterial populations associated with water from the scald tank, rubber fingers at the exit of the defeathering machine, and air in the dirty area were also characterized. Bacterial colonies (751) were randomly isolated from yeast extract-supplemented tryptone soya agar plates exhibiting 30 to 300 colonies. Micrococcus spp. were isolated in the highest proportion from pre-and postscalded carcass samples (63.5 to 86.1% of isolates), regardless of the sample type. Conversely, Enterobacteriaceae (40.3%), Acinetobacter (19.4%), and Aeromonas/Vibrio (12.5%) species predominated on neck skin samples taken from mechanically defeathered carcasses. Isolates from the rubber fingers were, however, predominantly Micrococcus spp. (94.4%). Bacterial groups isolated in the highest proportion from scald tank water samples were Micrococcus spp. (38.3%), species of Enterobacteriaceae (29.1%), and lactic acid bacteria (17.0%). Corynebacterium spp., species of Enterobacteriaceae, and Micrococcus spp. were dominant on air settle plates.

Latent turkey herpesvirus infection in lymphoid, nervous, and feather tissues of chickens

In earlier studies, we found that a late gene product, glycoprotein B (gB) was highly expressed in lymphoid tissues of chickens inoculated with turkey herpesvirus (HVT). The objectives of the present study were twofold. First, we wanted to expand on our previous research and determine if gB expression declines or disappears during later time periods of HVT infection. Second, we wanted to correlate gB expression with presence of HVT, i.e. if gB expression is absent, can HVT still be detected? Fifteen 1-day-old chicks were inoculated by intraperitoneal inoculation with 2000 plaque forming units of strain FC126 HVT. Thymus, spleen, bursa, brachial plexus, sciatic plexus, and feather tips were harvested at 21, 28, 35, 70, and 105 days postinoculation (PI). Brachial plexus and sciatic plexus were examined at 21, 28, and 35 days PI, and feather tips were examined at 21 and 28 days PI. An indirect immunofluorescence assay was used to detect HVT gB expression, and an in situ hybridization assay was used to detect HVT. At 21 days PI, gB expression was present in the thymus, spleen, and bursa. At 28 and 35 days PI, gB expression was detected in the thymus and spleen. At 70 days PI, gB expression was detected only in the spleen, and at 105 days PI, gB expression was not detected in any of the lymphoid tissue (thymus, spleen, or bursa). gB expression was not detected in the brachial plexus, sciatic plexus, or feather tips at any of the five time points. The bursa contained HVT only at 21 and 28 days PI. However, HVT was demonstrated in all other tissues from 21 to 105 days PI. Progression from a productive HVT infection to a latent HVT infection results in the loss of gB expression. Throughout this progression, a region of the HVT genome can be detected by appropriate methods.

Flagellin A gene restriction fragment length polymorphism patterns of Campylobacter spp. isolates from broiler production sources

The purpose of this study was to determine the potential reservoirs for Campylobacter spp. that provide the initial sources involved with broiler chicken colonization during poultry production. We characterized the flagellin A gene (flaA) of the organism by restriction fragment length polymorphism (RFLP) for 59 isolates of the bacterium provided during an epidemiological study. Isolates were obtained from three broiler production houses existing at separate locations. They were cultured and isolated from other (nonbroiler) domestic farm animals, wild birds, rodents, feed, farmers' boots, chicken feathers, and chicken intestinal materials. Eight distinctive flaA types were found in two of the houses. In one house, at least five flaA types (4, 6, 8, 15, and 21) were characterized from the poultry production environment, with three types isolated and identified from the chicken intestinal tract. flaA type 15 was found in flies, on boots, and in chicken intestinal samples. In another house, a distinctive diversity of flaA types existed (4, 7, 43, and 53). At least three flaA types found in samples from chicken intestinal tracts were also found in warm-blooded animals outside of the poultry house (domesticated animals, wild birds, and vermin).

First isolation of Salmonella blockley in Thailand

The first isolation of Salmonella blockley in Thailand was found in 2 strains of animal feed samples and 3 strains of chicken feather samples from a private poultry company in 1989. From 1987 to 1992, the number of S. blockley isolates increased and found in various sources. The major sources were the stools of diarrheal patients, mainly children. Another source of S. blockley was frozen chicken meat which increased every year studied. S. blockley isolated from human and other sources showed a high percentage resistance to streptomycin, tetracycline, kanamycin and chloramphenicol and a low percentage resistance to ampicillin and cotrimoxazole. Thus, S. blockley must now be listed as a possible cause of Salmonella food poisoning in Thailand.

Diagnosis of favus (avian dermatophytosis) in Oriental breed chickens

Chickens of various Oriental breeds (Shamo and Aseel) and crossbreeds in California's Central Valley were observed to have an unusual skin condition and feather loss. The appearance of white plaques on the comb, face, and/or ear lobes was followed by feather loss starting at the caudal base of the comb and progressing down the neck. Although the cocks were affected first, the condition spread to the hens paired with those cocks. The birds showed no other signs of illness. The affected areas were scraped and biopsied. The samples were examined histologically and by culturing on Sabouraud's dextrose agar and dermatophyte test medium. Microsporum gallinae, the causative agent of favus (avian dermatophytosis), was identified by the histological and mycological tests.

Laboratory diagnosis of psittacine beak and feather disease by haemagglutination and haemagglutination inhibition

Simple and sensitive haemagglutination and haemagglutination inhibition assays were developed for psittacine beak and feather disease (PBFD) virus and serum antibody, respectively. The assays were used in the examination of samples from 73 birds clinically affected with PBFD. High antigen titres (log2 9 to log2 12) were detected in feathers, faeces and cloacal contents of PBFD-affected birds. Antigen was not detected in either faecal or feather samples from 20 normal galahs (Eolophus roseicapillus) and 9 normal sulphur crested cockatoos (Cacatua galerita). After kaolin treatment and haemadsorption of serum, haemagglutination inhibition (HI) antibody titres could not be detected in serum from 42 PBFD-affected birds, whereas serum HI titres from 64 normal psittacine birds ranged from less than log2 1 to log2 8. Serum and yolk HI antibody responses of 6 PBFD virus-inoculated layer hens were measured. Pre-inoculation chicken sera contained high concentrations of non-specific haemagglutination inhibitors (not detected in chloroform-extracted yolk), which were removed by kaolin treatment and haemadsorption.

Synergism between the endogenous viral loci ev6 and ev9 in inducing immunological tolerance to avian leukosis virus

1. The course of infection by exogenous avian leukosis virus was followed in a commercial strain of White Leghorn domestic fowls by measuring viral antigen in feather pulp and egg albumin. Ten days after hatching, 2 out of 360 birds tested positive and at 286 days of age about 60% of the birds had been antigen positive at least once. 2. Among the antigen positive birds, two groups could be distinguished: those which permanently and those which transiently expressed viral antigen. Permanent antigen expression was associated with low antibody titres, while transient antigen expression was associated with high antibody titres. 3. The strain segregated for the two endogenous viral genes ev6 and ev9, both of which express endogenous viral envelope protein, and have been implicated in affecting immune-responsiveness. The antibody titre in individuals positive for both ev6 and ev9, was significantly lower than in those which had none or only one of the two ev-genes. In addition, individuals positive for both ev-genes occurred more frequently in the group permanently positive for viral antigen than in the group transiently antigen positive. 4. The results indicate that there was a strong synergism between ev6 and ev9 in reducing the antibody response to exogenous avian leukosis virus infection, perhaps by inducing immune tolerance or interfering with antibody formation.

Keratinolysis by Absidia cylindrospora and Rhizomucor pusillus: biochemical proof

Absidia cylindrospora and Rhizomucor pusillus causal agents of phycomycoses, were cultured on sterile natural keratins in a mineral solution and the keratin degradation products analyzed. The excess of sulphur was removed by oxidation to inorganic sulphate and thiosulphate, which were the main products of sulphitolysis of keratin. The proteolytic activity of the two fungi depended on the nature of the keratin substrate. Human scalp hair was the most favoured keratin substrate by both the fungi.

Distribution and numbers of Campylobacter in newly slaughtered broiler chickens and hens

If Campylobacter is present in the intestinal tract, broiler carcasses become extensively contaminated during the slaughter process. To determine the distribution and numbers of Campylobacter jejuni/coli in newly slaughtered broiler chickens and hens, a total of 100 birds from six Campylobacter-positive flocks were sampled at three Swedish processing plants. Campylobacters were isolated in 89% of neck skins, 93% of peritoneal cavity swab samples and in 75% of subcutaneous samples. Muscle samples were only very sparsely contaminated. It is likely that the feather follicles are the orifices where C. jejuni/coli is introduced into the subcutis layer.

Routes and prevalence of shedding of psittacine beak and feather disease virus

Psittacine beak and feather disease (PBFD) virus was recovered from the feces and crop washings from various species of psittacine birds diagnosed with PBFD. High concentrations of the virus also could be demonstrated in feather dust collection from a room where 22 birds with active cases of PBFD were being housed. The virions recovered from the feces, crop, and feather dust were confirmed to be PBFD virus by ultrastructural, physical, or antigenic characteristics. Virus recovered from the feather dust and feces hemagglutinated cockatoo erythrocytes. The specificity of the agglutination was confirmed by hemagglutination inhibition, using rabbit antibodies against PBFD virus. During the test period, 26% (8 of 31) of the birds screened were found to be excreting PBFD virus in their feces, and 21% (3 of 14) of crop washings were positive for PBFD virus. Some birds in the sample group had active cases of diarrhea, whereas others had normal-appearing feces. Diarrhea was found to be the only significant indicator of whether a bird was likely to be excreting virus from the digestive tract. These findings suggest that exposure of susceptible birds to PBFD virus may occur from contact with contaminated feather dust, feces, or crop secretions. Viral particles that were morphologically similar to parvovirus (20- to 24 nm-icosahedral nonenveloped virions) also were recovered from feces of some of the birds.

Favus in a backyard flock of game chickens

Favus, or avian ringworm, was diagnosed in a backyard flock of game chickens from which Microsporum gallinae was isolated. Infected birds had white crusts on the comb and on the skin of the head and neck. Histopathological lesions included hyperkeratosis of the skin epithelium with invasion of the stratum corneum by fungal mycelia, acanthosis, acantholysis, and hydropic degeneration of cells in the stratum spinosum. The underlying dermis was infiltrated by mononuclear cells and contained lymphoid foci. Daily topical treatment with miconazole was applied in the field and in the laboratory, with apparent success.

A novel DNA virus associated with feather inclusions in psittacine beak and feather disease

The nature of feather inclusions was characterized in 32 psittacine birds (30 cockatoos, one peach-faced lovebird (Agapornis roseicollis), and one red-lored Amazon parrot (Amazona autumnalis autumnalis] with naturally-acquired psittacine beak and feather disease. Intranuclear inclusions within feather epithelial cells and intracytoplasmic inclusions within macrophages in the feather epithelium and pulp cavity contained psittacine beak and feather disease viral antigen when stained by the avidin-biotin complex immunoperoxidase technique. Ultrastructurally, inclusions were observed primarily within macrophages and to a lesser extent within epithelial cell nuclei. Macrophage inclusions appeared as paracrystalline arrays of viral particles. Intranuclear inclusions were less well defined, although scattered viral particles were present. Intracytoplasmic and intranuclear particles in ultrastructural preparations were identified by colloidal gold labeling as psittacine beak and feather disease virus. Feather epithelium was more frequently and severely involved in the disease process than was adjacent follicular epithelium. Plucked feathers with an intact epidermal collar and feather epithelium were preferred to follicular biopsies for histopathologic examination.

The early pathogenesis in chicken inoculated with non-pathogenic serotype 2 Marek's disease virus

A newly cloned serotype 2 Marek's disease virus (MDV), strain ML-6, was inoculated via the nasal cavity in specific-pathogen-free chicks to examine early virus replication and the expression of Marek's disease (MD)-related antigens. Following inoculation, viral intracellular antigens (VIAs) were detected in lymphoid organs (bursas and spleens) between 5 and 14 days post inoculation (PI), in feather follicles between 14 and 30 days PI, and in lungs at 3 days PI by the immunohistopathological staining of avidin-biotin-peroxidase complex method. But, very few VIAs were expressed in the thymuses between 5 and 14 days PI. However, MD tumor-associated surface antigens were not detected in any organs. Viruses were isolated from separated spleen cells at 14 and 30 days PI. Fluorescent antibodies of convalescent sera were also detected after 10 days PI. As most of the VIAs were detectable in B-cells in bursas and spleens. B-cells were considered to be the main first target cells for the serotype 2 MDV infection.