Infected Poults Research Articles

PB1-F2 Protein Does Not Impact the Virulence of Triple-Reassortant H3N2 Swine Influenza Virus in Pigs but Alters Pathogenicity and Transmission in Turkeys

PB1-F2 protein, the 11th influenza A virus (IAV) protein, is considered to play an important role in primary influenza virus infection and postinfluenza secondary bacterial pneumonia in mice. The functional role of PB1-F2 has been reported to be a strain-specific and host-specific phenomenon. Its precise contribution to the pathogenicity and transmission of influenza virus in mammalian host, such as swine, and avian hosts, such as turkeys, remain largely unknown. In this study, we explored the role of PB1-F2 protein of triple-reassortant (TR) H3N2 swine influenza virus (SIV) in pigs and turkeys. Using the eight-plasmid reverse genetics system, we rescued wild-type SIV A/swine/Minnesota/1145/2007 (H3N2) (SIV 1145-WT), a PB1-F2 knockout mutant (SIV 1145-KO), and its N66S variant (SIV 1145-N66S). The ablation of PB1-F2 in SIV 1145 modulated early-stage apoptosis but did not affect the viral replication in swine alveolar macrophage cells. In pigs, PB1-F2 expression did not affect nasal shedding, lung viral load, immunophenotypes, and lung pathology. On the other hand, in turkeys, SIV 1145-KO infected poults, and its in-contacts developed clinical signs earlier than SIV 1145-WT groups and also displayed more extensive histopathological changes in intestine. Further, turkeys infected with SIV 1145-N66S displayed poor infectivity and transmissibility. The more extensive histopathologic changes in intestine and relative transmission advantage observed in turkeys infected with SIV 1145-KO need to be further explored. Taken together, these results emphasize the host-specific roles of PB1-F2 in the pathogenicity and transmission of IAV. Novel triple-reassortant H3N2 swine influenza virus emerged in 1998 and spread rapidly among the North American swine population. Subsequently, it showed an increased propensity to reassort, generating a range of reassortants. Unlike classical swine influenza virus, TR SIV produces a full-length PB1-F2 protein, which is considered an important virulence marker of IAV pathogenicity. Our study demonstrated that the expression of PB1-F2 does not impact the pathogenicity of TR H3N2 SIV in pigs. On the other hand, deletion of PB1-F2 caused TR H3N2 SIV to induce clinical disease early and resulted in effective transmission among the turkey poults. Our study emphasizes the continuing need to better understand the virulence determinants for IAV in intermediate hosts, such as swine and turkeys, and highlights the host-specific role of PB1-F2 protein.

Acquisition of immunity to the protozoan parasite Eimeria adenoeides in turkey poults and cellular responses to infection

Newly hatched turkey poults were infected with 102 oocysts of Eimeria adenoeides and subsequently reinfected with 103 and 104 oocysts at 6 and 12 d of age, respectively. Three peaks in oocyst production were observed in the feces of poults following this series of infections. A second group of poults given the same dosing regimen was challenged with 5 × 104 oocysts/poult at different times to evaluate the acquisition of immunity. Judging by weight gain and mortality, no protection had been acquired at 6 d of age, but partial protection was observed by 12 and 18 d of age. A third group of poults were also infected with 102 oocysts and subsequently reinfected with 103 and 104 oocysts at 6 and 12 d of age to evaluate cellular immune responses to infection. Sections of ceca from infected poults showed a significantly higher leukocyte infiltration on d 6, 10, 12, 16, and 18 after infection than uninfected controls. The percent area occupied by CD4+ and CD8+ lymphocytes in the ceca, as assessed by immunohistochemistry, was significantly elevated in infected poults on d 12, 16, and 18. The relative expression of chemokine CXCLi2, and cytokines IL1β, IFNγ, IL10, IL13, IL2, IL12b, and IL18 was measured by real-time reverse-transcription PCR. The expression of CXCLi2 and IL10 was found to be elevated on d 12, and IFNγ on d 10, 12, and 16. Expression of IL13 and IL18 was increased on d 10 and IL2 on d 10 and 16, and that of IL12b on d 16 in infected poults. Increase in the infiltration of leukocytes, percent area occupied by CD4+ and CD8+ lymphocytes, and changes in the relative expression of cytokines in the ceca characterize the dynamics of immune responses in turkey poults infected with E. adenoeides early in life.

Cellular immune responses, chemokine, and cytokine profiles in turkey poults following infection with the intestinal parasite Eimeria adenoeides

Cellular immune responses, chemokine, and cytokine profiles were investigated in 20-d-old turkey poults following an oral infection with 12.5 × 10(3) oocysts of Eimeria adenoeides, a protozoan parasite of the genus Eimeria that develops in the ceca. Large numbers of oocysts were produced in the feces of infected birds from d 5 after infection followed by a rapid decline by d 7. Local immune activities were characterized by observing the extent of leukocyte infiltration in the ceca by histology, measuring subsets of the lymphocyte population by immunohistochemistry, and determining the relative expression of cytokines by real-time, reverse-transcription PCR. Inflammation, assessed by scoring the extent of cellular infiltration of leukocytes in sections of ceca, was significantly higher in infected poults compared with uninfected poults on d 4, 7, 9, and 11 following infection. The percent area occupied by CD4+ and CD8+ cells in the ceca was significantly greater on d 9 and 11 (CD4+) and d 11 (CD8+) in infected poults compared with uninfected controls. The relative expression of the chemokine CXCLi2 and the cytokines interleukin (IL) 1β, interferon (IFN) γ, IL13, and IL10 was investigated in tissue samples taken from the ceca. Increased expression of CXCLi2 occurred on d 4 and 7. Increased expression of IL10 and IFNγ occurred on d 4 and of IL1β and IL13 occurred on d 7 postinfection. The increased leukocyte infiltration in the ceca, alterations in the lymphocyte subpopulations, and changes in expression of chemokines and cytokines are an indication of the cell-mediated immune mechanisms occurring in the host as a result of exposure to E. adenoeides.

Pathology and Tissue Distribution of Turkey Coronavirus in Experimentally Infected Chicks and Turkey Poults

SummaryTwenty 1-day-old specific pathogen free chicks and 20 1-day-old commercially derived turkey poults were inoculated with a Brazilian strain of turkey coronavirus (TCoV) to study the pathogenicity and virus distribution up to 14 days post-inoculation by histopathology, immunohistochemistry, reverse transcriptase polymerase chain reaction and sequencing. At 2–14 dpi, TCoV antigens were detected in the paranasal sinus and lachrymal accessory gland (Harderian gland) of infected chicks and in the ileum, ileocaecal junction and caecum of infected poults. Lymphocytic inflammation was present in these tissues. TCoV was re-isolated from pooled tissue suspensions of nasal concha, Harderian gland and paranasal sinus from chicks, as well as from the ileum, ileocaecal junction and caecum of poults, after three consecutive passages in 28-day-old embryonated turkey eggs. Viral RNA corresponding to the spike gene region (1178–2073 genome position) was amplified from the upper respiratory tract of chickens and from the intestinal tract of poults and phylogenetic analysis confirmed the identity as TCoV. This is the first description of TCoV antigens and mRNA in upper respiratory tissues in experimentally infected chickens.

Pathological and clinical findings and tissue distribution of Salmonella Gallinarum infection in turkey poults

This study aimed to experimentally induce Salmonella enterica subsp. enterica serovar Enteritidis (Salmonella Gallinarum) infection in turkey poults in order to detect S. Gallinarum using immunohistochemical, bacteriological, and histological procedures. The study included 90 white turkey poults that were divided into 3 groups (1-day-old, 3-week-old, and 2-month-old), each of which was orally inoculated with an inoculum of 0.3 mL of S. Gallinarum strain 9 broth culture that contained approximately 2 × 10^4, 1 × 10^6, and 1 × 10^9 cfu/mL, respectively. The duration of the experiment was 18 days. Clinical, pathological, and bacteriological findings were evaluated daily until 18 days post inoculation (pi). The most evident clinical symptoms in all 3 groups were diarrhea and somnolence, especially in 1-day-old group. S. Gallinarum strain 9 was isolated from organs and cloacal swabs up to 16 days pi. Inflammation and typical granulomatous nodules in the internal organs were observed in all 3 groups. Strong immunoreactivity was determined in the lungs, bursa of Fabricius, caecum, ileum, and cloaca of all infected poults up to 18 days pi. In conclusion, S. Gallinarum infection caused heterophilic granulomas, especially in the duodenum of turkey poults, and immunohistochemical analysis can be considered as an adjunct to bacteriological methods in the diagnosis of S. Gallinarum infection.

Acquisition of immunity to the protozoan parasite Eimeria adenoeides in turkey poults and the peripheral blood leukocyte response to a primary infection

A primary infection of 12.5 x 10(3) oocysts of Eimeria adenoeides , given to 20-d-old turkey poults, resulted in depression of weight gain, and the production of large numbers of oocysts in the feces, compared with uninfected controls. Poults were raised under conditions to prevent possible reinfection to determine the ability of the primary infection to confer protective immunity against a challenge infection of 5 x 10(4) oocysts given at 34 d of age. Using weight gain and oocyst production after challenge as criteria for protection, the results indicated that immunity had developed. The concentration and proportions among white blood cell (WBC) populations in peripheral blood were determined at different times after the primary infection. The WBC concentration of infected poults was elevated on d 7 and 11, primarily due to elevated levels of lymphocytes and monocytes on d 7 and eosinophils on d 11. There were no differences in heterophil and basophil concentrations between infected and uninfected poults at any of the time points examined. With the exception of increased percentages of eosinophils on d 11, infection was not associated with alterations in the proportions among WBC populations. Comparison of CD4+ and CD8+ defined lymphocyte subpopulations in the blood of infected versus uninfected poults revealed higher concentrations of CD4+ lymphocytes on d 11, lower concentrations of CD8+ cells on d 4, and higher concentrations of CD8+ cells on d 11 of infection, as well as elevated ratios of CD4+:CD8+ lymphocytes in infected birds on d 4 and 11. These alterations in WBC profiles after primary E. adenoeides infection in turkey poults suggest initiation of both innate and adaptive cellular immune activities designed to effectively cope with a parasitic, intracellular pathogen.

Infection with a pathogenic turkey coronavirus isolate negatively affects growth performance and intestinal morphology of young turkey poults in Canada

Turkey coronavirus (TCoV) is an important viral pathogen causing diarrhoea of young turkey poults that is associated with sizeable economic losses for the turkey industry. Using a field isolate that was found to be free from turkey astrovirus and avian reovirus we were able to reproduce the clinical disease associated with TCoV. Clinical signs and weight gain of poults during experimental infections were compared with age-matched, uninfected controls. Poults infected at 2 days of age had 100% morbidity and 10% mortality, and birds infected at 28 days of age showed 75% morbidity and no mortality. Diarrhoea was consistently seen in infected poults at 2 to 3 days post infection (d.p.i.) with a duration of about 3 to 5 days. Mean body weights of birds infected at 2 or 28 days of age were significantly reduced compared with uninfected birds by 7 d.p.i. and remained significantly lower for the duration of the study. At 44 days of age, poults infected at 2 or 28 days of age weighed only 68.1% or 77.7%, respectively, compared with uninfected turkeys of the same age on the same diet, a mean difference in body weights of 683 or 477g, respectively. Infected birds had profound villus atrophy with some compensatory crypt hyperplasia at 5 to 7 d.p.i. Villus heights in the duodenum were significantly reduced at 7 d.p.i. We were able to reproduce enteric disease using only a pathogenic field isolate (MG10) of TCoV that negatively affected growth performance and intestinal morphology of young turkey poults.

AvianMycoplasma lipofaciensTransmission to Veterinarian

To the Editor: Mycoplasma spp. are well-known pathogens in human and veterinary medicine. Mammals, especially primates and including humans, share similar or even identical Mycoplasma spp., which might be commensal or pathogenic (1). Additionally, sporadic infections of immunocompromised persons with Mycoplasma spp. that originated from domestic animals have been reported (1); susceptibility in this human population is increased (2,3). M. phocicerebrale is the only Mycoplasma pathogen of animals that regularly infects humans, causing a disease called seal fingers (1,4). However, we report a human infection with an avian Mycoplasma organism. A clinical trial to investigate the capability of M. lipofaciens (strain ML64) (5) to spread horizontally between infected and noninfected turkey poults in an incubator demonstrated airborne transmission of the pathogen within 24 hours (6). During the trial, the veterinarian conducting the study, a 36-year-old man, was monitored for infection. Each day, 2 swabs were taken from both nostrils, starting from the day before the infected poults hatched (day 0) through day 7 after the poult hatching date. When handling eggs and poults, the veterinarian wore gloves but not a protective mask. Two days after the poults hatched (day 3), the veterinarian reported throat pain and a slight rhinitis, which indicated a respiratory disease. The next day only the rhinitis with minor nasal pain was present. One nasal swab from each sampling day was used for Mycoplasma spp. culture (5). Isolated Mycoplasma organisms were subjected to an immunobinding assay (6) with antiserum against M. lipofaciens, M. buteonis, M. falconis, M. gypis, M. gallisepticum, M. meleagridis, M. synoviae, and M. iowae, selected because the veterinarian regularly handled these isolates. The second nasal swab from each sampling day was taken to detect Mycoplasma DNA by PCR (5). The samples for PCR testing were stored at –20°C and tested only when attempts to isolate Mycoplasma spp. failed. Six weeks after the infection, a serum sample from the patient was examined for specific antibodies against M. lipofaciens by 3 different methods: modified immunobinding assay (6) (which used patient’s serum and peroxidase-conjugated goat-antihuman serum [STAR90P, Serotec Ltd, Oxford, UK]), a growth inhibition test, and antibody titers of serum dilutions. The first 2 methods used M. lipofaciens (strain ML64) from a turkey trial (6) and the reference strains of M. buteonis (Bb/T2g) and M. falconis (H/T1). For the third method, to determine the titer, 2-fold serial dilutions of the patient’s serum samples were prepared and incubated with a bacterial suspension (M. lipofaciens strain ML64) containing 3.2 × 102 CFU. The antibody titer was based on the highest serum dilution capable of reducing 50% of the mean CFU count. Before the infected poults hatched, attempts to isolate Mycoplasma organisms and demonstrate Mycoplasma DNA from the nasal swabs were unsuccessful. However, from the day of hatching (day 1) until 3 days later (day 4), Mycoplasma organisms were isolated from the nasal swabs and identified as M. lipofaciens. On day 5, only Mycoplasma DNA was demonstrated (Table). Specific antibodies against M. lipofaciens (strain ML64) were detected by using the immunobinding assay and growth inhibition test. Antibodies against other Mycoplasma spp. were not detected. Antibody titer against M. lipofaciens was 128. Table Timeline of natural infection of veterinarian with Mycoplasma lipofaciens (strain ML64) from infected poults* M. lipofaciens have been reported from a chicken, turkey, duck (7,8), and a raptor egg (5). Strain ML64 is highly pathogenic for chicken and turkey embryos and can be transmitted by air (6,9). The veterinarian handling the infected poults was free of nasal Mycoplasma organisms a day before contact. His infection occurred concurrent with demonstration of airborne transmission among poults. The isolation of M. lipofaciens from his nares for 4 days demonstrates the infectivity and reproductive capability of this Mycoplasma strain in humans: as a pure contaminant, isolation for several days would be unlikely. Christensen et al. (10) have reisolated different avian Mycoplasma strains (M. gallisepticum, M. synoviae, M. iowae) from a human nose, from 12 hours through 1 day after artificial infection, demonstrating differences between avian strain abilities to survive on human mucosa. M. lipofaciens invasiveness for humans is underscored by finding specific antibodies against this species 6 weeks after infection. Cross-reactivity to other Mycoplasma spp. cannot be excluded but seems unlikely. This study suggests that M. lipofaciens (strain ML64) can be transmitted successfully to humans and may cause clinical symptoms; the study documents nonartificial human infection with an avian Mycoplasma sp. These findings should be considered especially for humans highly susceptible to Mycoplasma infections, including children and persons with congenital or acquired immunodeficiencies (2,3).

Immunohistochemistry Assay to Detect Turkey Coronavirus (TCoV) from Experimentally Infected Poults

The objective of this study was to develop a direct immunohistochemical assay to detect TCoV antigens in formalin-fixed paraffin-embedded sections prepared from experimentally infected poults. The sections of ileo, ileo-cecal junction and ceca regions from intestine were prepared and submitted to two different primary antibodies, first the non-biotin labeled polyclonal antibody for the indirect method, and second the biotin-labeled polyclonal antibody, both raised against IBV by immunized specific pathogen free chickens. All sections were submitted to immufluorescent assay (IFA), a conventional method, and the results compared. The direct immunohistochemical technique showed a higher frequency of antigen in tissues, especially from the ileo-cecal junction with no difference between results obtained by the conventional method. Finally, the immunofluorescence and all modalities of molecular approaches have been played an important role to the diagnosis and prevention of TCoV infections, although to be precise on infectious disease diagnosis, it is necessary complementary techniques. Here, was standardized the biotin labeled polyclonal antibody as reliable tool to be used as an alternative detection of Turkey Coronavirus.

Pathogenicity of Turkey Astroviruses in Turkey Embryos and Poults

The pathogenicity of turkey astrovirus 2001 (TAstV2001) and turkey astrovirus 1987 (TAstV1987) in specific-pathogen-free (SPF) turkey embryos and commercial poults was investigated. The virus shedding in poults was monitored using electron microscopy (EM) and reverse transcription-polymerase chain reaction (RT-PCR) during the 14-day experimental period. Both viruses caused enteritis and growth depression in SPF turkey embryos and poults. The TAstV2001 did not induce macroscopic or microscopic lesions in thymuses and bursas of embryos or poults. No macroscopic changes were observed in thymuses and bursas of embryos and poults inoculated with TAstV1987, and no statistically significant differences in bursa weight/ body weight ratios (P > 0.05) were detected. However, TAstV1987 infection resulted in microscopic lesions in bursas but not in thymuses of infected embryos and poults. Both TAstV2001 and TAstV1987 were shed during the whole 14-day experimental period as detected by EM and RT-PCR. These findings indicated that both TAstV1987 and TAstV2001 are etiologic agents of turkey enteritis. In addition, TAstV1987 might cause impairment of the immune system of infected poults. The pathogenicity of TAstV1987 is somewhat different from TAstV2001.

Development of Antigen-Capture Enzyme-Linked Immunosorbent Assay and RT-PCR for Detection of Turkey Astroviruses

Turkey astrovirus (TAstV) is an important agent of poult enteritis. The diagnosis of astroviruses has been dependent mainly on electron microscopy (EM) or immune EM (IEM). To develop other simple, rapid, and reliable diagnostic assays, two antigen-capture enzyme-linked immunosorbent assays (AC-ELISAs), polyclonal AC-ELISA and monoclonal AC-ELISA, were developed in this study. Monoplex and multiplex reverse transcription-polymerase chain reactions (RT-PCRs) were also developed using nondegenerate primer sets specific to the capsid region and degenerate primer pairs specific to the polymerase area of two TAstV. EM was included for comparison. Fecal or intestinal contents samples from naturally and experimentally infected poults with enteritis were examined using the developed assays. The polyclonal AC-ELISA had higher sensitivity and wider detection spectrum than the monoclonal AC-ELISA with group-specific monoclonal antibody (MAb), whereas the monoclonal AC-ELISA had very high specificity but lower sensitivity, which was estimated at 0.06 microg of viral proteins. Small round viruses (SRV) that could be astroviruses or other small viruses were detected in 34.4% of the samples examined by EM. The monoplex RT-PCR results amplified with primers SRV-1-3 and SRV-1-5 revealed that the positive rate of astroviruses was 45.3%, which was 10.9% higher than that of EM even if other SRVs were not excluded. Multiplex RT-PCR with SRV-1-3 and SRV-1-5 and AFCP-F1 and AFCP-R1 and the monoplex RT-PCR with degenerate primers verified that the positive rate of astroviruses was 59.4%, which was 25% higher than that of EM. Both RT-PCRs showed good specificity and wider detection spectrum compared with earlier published data.

The Comparison of an Aqueous Preparation of Tilmicosin with Tylosin in the Treatment of Mycoplasma gallisepticum Infection of Turkey Poults

A virulent strain of Mycoplasma gallisepticum (MG) was used to infect groups of 40 2-day-old poults kept in separate pens of 10 each. Of the six groups, three were treated with separate concentrations of tilmicosin, one was treated with tylosin, one remained untreated, and a final group was not infected and not treated. Mortality, clinical signs, and gross lesions were significantly less (P < 0.001) in the uninfected and infected medicated groups than in the infected unmedicated group. Also, the mean body weight gain of poults surviving to the end of the experiment was greater (P < 0.005) in the uninfected and infected medicated groups. MG was not recovered from the uninfected birds, and, among the infected poults, it was recovered from significantly fewer (P < 0.05) poults in the medicated groups. Serologic results were negative for the uninfected group, and there were fewer positive reactors for the infected medicated than the infected unmedicated group. In consideration of these results, tilmicosin should prove to be a useful addition to the antimicrobials in the treatment of MG infection in poults.

The effects of Bordetella avium infection on elastin and collagen content of turkey trachea and aorta

Turkey poults were inoculated at hatch with the “W” isolate of Bordetella avium. At 17 d of age, serum copper levels and ceruloplasmin activities were determined. The trachea and aorta were analyzed for collagen and elastin content in an attempt to relate these structural proteins to the clinical observations of tracheal ring distortion and cardiac dysfunction associated with bordetellosis. Serum copper levels and ceruloplasmin activity were elevated in the B. avium-infected poults and indicated enzyme activity sufficient for elastin and collagen cross-link formation. In the infected poults, crude elastin content was increased significantly (0.67% infected vs 0.59% control) in the trachea but not in the aorta (13.12% infected vs 12.68% control). However, collagen content in infected poults (69.7 hydroxyproline residues per 1,000 amino acid residues) was decreased in the trachea compared to the controls (97 hydroxyproline residues per 1,000 amino acid residues), whereas collagen and elastin cross-links (HLNL, hydroxy-lysinohydroxy-norleucine, moles per mole of collagen per 300 residues hydroxyproline) were increased in the trachea of infected poults (2.85 in infected vs 1.80 in control) and also increased (DHLNL, dihydroxy-lysinohydroxy-norleucine, moles/mole of collagen/300 residues hydroxyproline) in the aorta (0.49 in infected vs 0.39 in control) of infected poults. The differences in collagen and elastin content, in association with differences in the cross-linking, appeared to be the cause of tracheal collapse that is characteristic of B. avium infection and also may have an adverse influence on cardiovascular function.

Effect of litter moisture and brooding temperature on body weights of turkey poults experiencing poult enteritis and mortality syndrome

Studies were conducted to determine the influence of the interactions among litter moisture (high [HiM]> or =40% vs low [LoM]< or =20%), brooding temperature (high [HiB] = 38 C vs normal [NrB] = 34 C), and development of poult enteritis and mortality syndrome (PEMS) as indicated by body weights, relative weights of lymphoid organs, and mortality in Control [C] vs Infected [I] groups. There was a significant interaction between litter moisture and brooding temperature that had a significant influence on BW. The brooding temperature main effect was not significant, but there was a significant litter moisture effect on BW. Body weights were suppressed by PEMS infection, but infected poults brooded at HiB on LoM had significantly greater BW than those brooded at NrB and HiB on HiM. Main effects showed that there were significant litter moisture- and brooding temperature-mediated responses for BW. Relative weights of lymphoid organs revealed significant disease main effects but no effect due to brooding temperature and litter moisture. There was a significant effect of disease and brooding temperature with regard to mortality. The results from this study suggest that litter moisture influences productivity and mortality associated with PEMS, but brooding temperature has the greatest influence on PEMS-associated mortality. Therefore, higher brooding temperature for turkey poults being placed into a facility where they may be at risk for PEMS exposure is recommended.

Improvement of Poult Performance Following Bordetella avium Challenge by Administration of a Novel Oxy-Halogen Formulation

The ability of a novel oxy-halogen formulation (OHF) to alter the development of bordetellosis (turkey coryza) in large white turkey poults was assessed. Bordetella avium (BA)-infected (1-day-of-age) and noninfected control poults received 0, 0.008%, or 0.016% of an OHF continuously in the drinking water. At 4, 7, 10, 14, and 17 days of age, reisolation of BA from infected poults was attempted. Infected poults receiving 0.016% OHF exhibited significantly lower cumulative BA reisolation rates (90%) when compared with infected poults receiving 0 (96.7%) or 0.008% OHF (100%). At 7, 14, and 17 days of age, infected poults in the OHF-treated groups were significantly heavier than those BA-challenged poults receiving control water. Feed utilization was significantly improved from hatch to 7 days of age in BA-infected poults receiving OHF when compared with infected poults receiving control water. Clinical symptoms were severe only in untreated, infected poults and were mild or absent in all others. Damage to the tracheal epithelium, as measured by scanning electron microscopy, paralleled the clinical signs. Tracheal epithelial damage was virtually eliminated by OHF administration in infected poults. These results suggest that OHF treatment ameliorates many of the symptoms frequently associated with bordetellosis in young turkeys.

Experimental Infection of Turkey Poults with Western Equine Encephalitis Virus

The pathogenicity of a field isolate of western equine encephalitis (WEE) virus, which was recovered from a breeder hen during investigations of egg production drops in California turkey flocks, was tested in 2-wk-old turkey poults. No symptoms or mortality were observed in poults inoculated intramuscularly with 4.2 log10 50% embryo lethal doses of virus; however, the infection did result in mild to moderate lymphoid necrosis in the bursa of Fabricius and thymus glands beginning on the first day postinoculation. In addition, WEE virus could be isolated from the blood of infected poults for up to 3 days postinoculation.

Optimising the conditions for isolation of Mycoplasma gallisepticum collected on applicator swabs

An experiment to compare the recovery of Mycoplasma gallisepticum (Mg) on dry swabs and swabs wet with mycoplasma broth (MB) was carried out by swabbing choanal clefts of Mg infected turkey poults at days 3, 6, 9, 12 post-infection. Wet swabs yielded significantly greater numbers of mycoplasmas than dry swabs on three out of four sampling days. When low numbers of mycoplasmas were collected on wet or dry swabs (in vitro) and then stored at room temperature (RT) or 4°C for various intervals, those on dry swabs at RT had lost viability by 8 to 24 h. They survived at least 24 h on wet swabs kept at 4°C. When Mg was collected and stored on dry and wet swabs from experimentally infected poults survival was again best on wet swabs stored at 4°C. Swabs pre-wet with MB and stored before sampling could be used without any ill effects on mycoplasma recovery as long as they were stored at 4°C and for no more than 48 h. After storage at RT for 48 h such swabs appeared to be detrimental to the organism. Mg collected on wet charcoal swabs was viable for 48 to 72 h when kept at 4°C whereas it was viable for only 24 h when stored at RT. Mg was recovered from wet charcoal swabs sent through the mail but not from dry or wet plain swabs.

A Sequential Histopathologic and Immunocytochemical Study of Chickens, Turkey Poults, and Broiler Breeders Experimentally Infected with Turkey Rhinotracheitis Virus

The histopathologic changes and the distribution of turkey rhinotracheitis virus (TRTV) antigen in the respiratory and reproductive tracts of experimentally infected chickens, turkey poults, and broiler breeders is described. TRTV antigen was detected using both immunofluorescent staining of cryostat sections and immunoperoxidase staining of formalin-fixed tissues. Viral antigen was observed associated with the cilia of the epithelial cells of turbinates, trachea, and lung. No TRTV antigen and no histopathologic changes were detected in the conjunctiva of any of the sacrificed birds, or in the reproductive tract and central nervous system of broiler breeders. The main histopathologic lesions and sites of TRTV replication were observed in the ciliated epithelial cells of turbinates and lung. These findings bring forward new information about pathologic changes and TRTV antigen distribution in tissues of experimentally infected birds.

Development of an Antigen-Capture Enzyme-Linked Immunosorbent Assay for Detection of Enterovirus in Commercial Turkeys

Diagnosis of enterovirus infection in turkey poults is currently done using electron microscopy. We have developed an antigen-capture enzyme-linked immunosorbent assay (ELISA) for use in diagnosis of enterovirus infection in turkey intestinal contents. Intestinal contents from naturally and experimentally infected turkey poults were evaluated for the presence of astrovirus and enterovirus by immune electron microscopy (IEM). The results were compared with the findings obtained using the ELISA for the presence of enterovirus. The ELISA, using the samples from the naturally infected poults, had a sensitivity of 0.963 and a specificity of 0.879. The Kappa value of 0.834 for the naturally infected samples and 0.97 for the experimentally infected samples showed excellent agreement between the ELISA and IEM for detection of enterovirus. Our results indicate that the ELISA is a rapid, sensitive, and specific method for diagnosis of turkey enterovirus infection.

Tracheal Cilia Response to Exogenous Niacin in Drinking Water of Turkey Poults Infected with Bordetella avium

Niacin was added daily to the drinking water of control and Bordetella avium-infected turkey poults at a dosage of 0, 70, and 280 mg/liter over a 2-week experimental period. Fourteen days postinoculation, tracheal sections were examined by histological and morphometrical analysis of cilia, as well as agar plate isolation for bacteria. Infected poults exhibited a 96-97% loss of cilia along the tracheal epithelial border, compared with only a 4-5% loss in controls. Infected poults receiving niacin in the drinking water exhibited only a 61.0% and 76.0% loss of cilia at doses of 70 mg/liter and 280 mg/liter, respectively. The results indicate that niacin treatment may influence the pathogenicity of B. avium infection.