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Duration of Growth Depression and Pathogen Shedding in ExperimentallyReproduced Poult Enteritis SyndromeAuthor(s): Naresh Jindal, Devi P. Patnayak, Andre F. Ziegler, Alfonso Lago, and Sagar M. GoyalSource: Avian Diseases, 53(4):517-522. 2009.Published By: American Association of Avian PathologistsDOI: http://dx.doi.org/10.1637/8845-040709-Reg.1URL: http://www.bioone.org/doi/full/10.1637/8845-040709-Reg.1

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Duration of Growth Depression and Pathogen Shedding in ExperimentallyReproduced Poult Enteritis Syndrome

Naresh Jindal, Devi P. Patnayak, Andre F. Ziegler, Alfonso Lago, and Sagar M. GoyalA

Department of Veterinary Population Medicine, College of Veterinary Medicine, University of Minnesota, 1333 Gortner Avenue,Saint Paul, MN 55108

Received 17 April 2009; Accepted and published ahead of print 4 July 2009

SUMMARY. An experimental study was conducted to determine the duration of growth depression and virus shedding inturkey poults after oral inoculation with intestinal contents from birds affected with poult enteritis syndrome (PES). Poults at day14 of age were divided into four groups (groups A, B, C, and D) of 40 poults each and inoculated orally with unfilteredsupernatant, filtered supernatant, sediment suspended in phosphate-buffered saline (PBS), or PBS alone (control), respectively. Thepoults were observed daily for clinical signs, and their growth response, pathology, and pathogen shedding were examined at 10, 20,30, 40, and 50 days postinoculation (DPI). Body weights of eight poults in each group were recorded at each of these intervalsfollowed by euthanasia. Dullness, depression, and diarrhea were observed in birds inoculated with supernatant or sedimentsuspension. All three treatments significantly reduced body weight gain of poults compared with the control group; average weightloss was 14%. Gross pathologic changes consisted of pale distended intestines with watery contents and distended ceca with frothyand watery contents. Astrovirus and rotavirus were detected in the inoculum by reverse transcription (RT)-PCR, whereasSalmonella was identified on bacterial isolation. Both viruses were detected in treated poults by RT-PCR for up to 10 and 40 DPI,respectively. Of the three treatments, sediment suspension caused maximal decrease in weight gain as well as greatest pathologiclesions followed by unfiltered supernatant and filtered supernatant. These findings suggest a role for bacteria in increasing theseverity of PES. Lower weight gain in treated poults (compared with controls) at 9 wk of age also indicates that PES-affected poultsmay not reach normal weight at marketing, leading to economic losses for the producer.

RESUMEN. Duracion de la baja en el crecimiento y eliminacion del patogeno por la enteritis de los pavipollos reproducidaexperimentalmente.

Se realizo un estudio experimental para determinar la duracion de la baja en el crecimiento y la eliminacion viral en pavipollosdespues de la inoculacion oral con contenidos intestinales de aves afectadas con el sındrome de la enteritis de los pavos. Pavipollosde catorce dıas de edad fueron divididos en cuatro grupos (grupos A, B, C, y D) con cuarenta pavipollos cada uno. Los gruposfueron inoculados oralmente con un sobrenadante no filtrado, con un sobrenadante filtrado, con el sedimento en suspension consolucion amortiguadora de fosfatos (PBS) o con PBS solamente (grupo control), respectivamente. Los pavipollos fueron observadosdiariamente para detectar signos clınicos y su respuesta en el crecimiento. Las lesiones y la eliminacion del patogeno se examinaron alos 10, 20, 30, 40 y 50 dıas despues de la inoculacion. Los pesos corporales de ocho pavipollos en cada grupo fueron registrados entodos estos intervalos despues de la eutanasia. Se observo letargo, depresion y diarrea en las aves inoculadas con sobrenadante o conla suspension del sedimento. Todos los tratamientos redujeron significativamente la ganancia en el peso de los pavipollos inoculadosen comparacion con el grupo control, el promedio en la disminucion de peso corporal fue de 14%. Los cambios patologicosmacroscopicos consistieron de intestinos distendidos, palidos con contenido acuoso y sacos ciegos distendidos con contenidosespumosos y acuosos. Se detecto astrovirus y rotavirus en el inoculo mediante la transcripcion reversa y la reaccion en cadena de lapolimerasa (RT-PCR), mientras que se identifico Salmonella sp en los aislamientos bacterianos. Ambos virus fueron detectadosmediante la RT-PCR en los pavipollos tratados hasta los 10 y 40 dıas despues de la inoculacion, respectivamente. De los trestratamientos, el sedimento suspendido causo la mayor disminucion en la ganancia de peso ası como las lesiones mas severas, seguidodel sobrenadante sin filtrar y el sobrenadante filtrado. Estos hallazgos sugieren que bacterias juegan un papel aumentando laseveridad de la enfermedad. El bajo peso en los pavipollos tratados (en comparacion con las aves del grupo control) a las nuevesemanas de edad y tambien indica que las aves afectadas posiblemente no alcancen el peso normal al momento de salir al mercado,produciendo perdidas economicas para los productores.

Key words: poult enteritis syndrome, growth depression, pathogen shedding

Abbreviations: bp 5 base pairs; DPI 5 days postinoculation; EM 5 electron microscopy; PBS 5 phosphate-buffered saline;PEC 5 poult enteritis complex; PEMS 5 poult enteritis and mortality syndrome; PES 5 poult enteritis syndrome; RT 5 reversetranscription; SMT 5 spiking mortality of turkeys; SRV 5 small round virus(es); TAstV-2 5 turkey astrovirus-2

Minnesota turkey growers and poultry veterinarians haveencountered a disease in young turkeys and have named it ‘‘poultenteritis syndrome’’ (PES). From 2002 to 2007, the MinnesotaVeterinary Diagnostic Laboratory received 151 cases of PES. Thedisease seems to be multifactorial in etiology because severalpathogens were identified in the affected birds, e.g., rotavirus, smallround viruses (SRV), reovirus, adenovirus, Salmonella, Escherichiacoli, Enterococcus spp., and Eimeria spp. However, a majority of cases

revealed the presence of rotavirus or Salmonella or both (14). Noneof the PES cases from Minnesota was positive for coronavirus,although this virus is the primary agent identified in a similarsyndrome called the ‘‘poult enteritis and mortality syndrome’’ orPEMS (11,41).

Small round viruses are 15–30 nm in diameter and includeenterovirus, astrovirus, and picorna-like virus. Although these viruseshave distinct morphologies (6), they may not be clearly distinguish-able (39) by electron microscopy (EM), a method of choice for thedetection of enteric viruses in livestock and poultry (10). Thus, onACorresponding author. E-mail: goyal001@umn.edu

AVIAN DISEASES 53:517–522, 2009

517

the basis of EM alone, it may be difficult to determine which SRV isinvolved in enteric disease, and there is a risk of misidentification/misclassification of the etiologic agent (39). In addition to beingsubjective, the EM results are not as sensitive as molecular methodssuch as the reverse transcription (RT)-PCR. In fact, we were unableto detect astrovirus in several PES cases by EM, although these samesamples were astrovirus-positive when examined by RT-PCR (Jindal,unpubl. data).

We previously conducted experiments to reproduce PESexperimentally by oral inoculation of 14-day-old turkey poults withintestinal contents from PES-affected birds (15). The inoculumcontained rotavirus, astrovirus, and Salmonella. In addition todiarrhea and depression, an average weight reduction of 31.8% wasobserved in treated poults (15). The poults in that study weremonitored for only 20 days postinoculation (DPI). To better assesslong-term growth depression, a longer duration of study was desired.If the trend of growth depression continues for a longer duration, theturkey growers stand to incur considerable economic losses due toreduced body weight at marketing age.

In fact, another syndrome has been observed in Minnesota turkeyscalled the ‘‘light turkey syndrome,’’ in which the turkeys weighconsiderably less than expected weight at marketing age (23–24 wk).We believe that PES sets the stage for turkeys to be light weight atmarketing. With this in mind, we conducted an experiment to studythe effects of PES on growth response and pathogen shedding inexperimentally inoculated poults for up to 9 wk of age (50 DPI).

MATERIALS AND METHODS

Source of inoculum. Twenty birds (2 wk of age) showing clinicalsigns of PES (diarrhea, depression, and lethargy) were selected from aPES-affected commercial turkey flock. The birds were killed by cervicaldislocation and necropsied. Homogenates of tissue pool comprisingvisceral organs (other than gastrointestinal tract) were examined forSalmonella by first enriching it in tetrathionate brilliant-green bile-enrichment broth for 24 hr at 37 C followed by subcultivation onbrilliant green agar for 24 hr at 37 C. Salmonella-like colonies werepicked and confirmed by slide agglutination using polyvalent antiserumagainst Salmonella spp. The intestinal contents from these same birdswere pooled, homogenized, and divided into three separate parts. Part 1was examined for the presence of enteric viruses (astrovirus, rotavirus,coronavirus, and reovirus) by EM (10) and RT-PCR (see below); part 2was examined for protozoa (Eimeria sp.) by fecal flotation (35); and part3 was processed further for the preparation of experimental inoculum.

Preparation of inoculum. A 10% suspension of pooled intestinalcontents (part 3) was prepared in phosphate-buffered saline (PBS;pH 7.4). The suspension was homogenized in a stomacher followed bycentrifugation at 784 3 g for 20 min. The supernatant was divided intotwo equal portions; portion 1 was used as an inoculum without anyfiltration and was named unfiltered supernatant, whereas portion 2 wasfiltered through a 0.22-mm filter coated with 4% fetal bovine serum andwas named filtered supernatant. The supernatants and the pellet(sediment) were stored at 220 C until use. Before use, the sediment wassuspended in 80 ml of PBS. Before inoculation, the unfilteredsupernatant was tested for enteric viruses by RT-PCR, and the sedimentsuspension was tested for Salmonella.

Experimental protocol. One-day-old male turkey poults (n 5 160)were procured from a commercial hatchery. The poults were placed inan isolation building and were given a starter diet from the first day untilthe end of the experiment. At day 14 of age (day 0 of experiment), thepoults were divided into four groups with 40 poults in each group(groups A, B, C, and D). Each group was placed in a separate room so asto avoid the spread of pathogens from one group to the other. Poults ingroup A were inoculated with unfiltered supernatant orally at 2 ml/bird.Poults in groups B and C were inoculated with filtered supernatant and

sediment suspension, respectively. Group D poults were inoculated withPBS alone, and this group was named the control group. The dose androute of inoculation in groups B, C, and D were the same as in group A.Groups A, B, and C are referred to as the ‘‘treated’’ groups in this study.The animal care protocol for this experiment was approved by theInstitutional Animal Care and Use Committee of the University ofMinnesota.

Clinical observations and growth response. Poults in all fourgroups were observed daily for 50 DPI (64 days of age) for thedevelopment of clinical signs and mortality. Before inoculation (0 day ofexperiment), eight randomly selected poults from each of the fourgroups were weighed to determine baseline weights. Subsequently, eightrandomly selected poults from each of the four groups were weighed atfive different intervals (10, 20, 30, 40, and 50 DPI). Weight gain at eachinterval in each group was calculated by subtracting the mean bodyweight of poults at 0 day of experiment from mean body weight ofpoults at the current interval. For example, weight gain in group A at 10DPI was calculated by subtracting mean body weight at 0 day ofexperiment from mean body weight at 10 DPI. Overall growthdepression (%) in the treated groups due to PES was calculated by thefollowing formula: 100 2 [(average of mean treatment effect weightgain values in groups A, B, and C/mean treatment effect weight gainvalue in group D) 3 100].

Necropsy findings and pathogen detection. After weighing, thepoults at 10, 20, 30, 40, and 50 DPI were euthanatized, and grosspathologic changes were recorded. Livers and spleens from eight poultsin each group at each interval were pooled, homogenized, and examinedfor Salmonella as described above. Intestinal contents of these birds werepooled and examined for enteric viruses by EM and for coccidia by fecalflotation. A part of the pooled sample was mixed with PBS, pH 7.4, tomake a 10% suspension. This suspension was homogenized andcentrifuged at 784 3 g for 20 min, and the supernatant was tested forthe presence of enteric viruses by RT-PCR.

RNA extraction. Total RNA was extracted from unfilteredsupernatant of the inoculum, supernatants of pooled intestinal samplesfrom all groups, a turkey rotavirus (kindly provided by Prof. Y. M. Saif,Ohio Agricultural Research and Development Center, Wooster, OH),turkey astrovirus-2 (TAstV-2), and turkey coronavirus (NC95; kindlyprovided by Prof. J. Guy, North Carolina State University, Raleigh,NC). The latter three were used as positive controls. Two hundred andfifty microliters of each sample was used for extraction of total RNA byusing the TRIzol LS reagent (Invitrogen, Carlsbad, CA).

RT-PCR for rotavirus, astrovirus, and coronavirus. ExtractedRNAs were subjected to RT-PCR for the detection of rotavirus,astrovirus, and coronavirus using virus-specific primers (Table 1). TheRT-PCR was performed using OneStep RT-PCR kit (QIAGEN,Valencia, CA). The reaction mix and reaction conditions used foramplification of these viruses by RT-PCR have been describedpreviously (15). The position of the bands on agarose gel at 630 basepairs (bp), 849 bp, and 598 bp confirmed the presence of rotavirus,astrovirus, and coronavirus, respectively. PCR products were purifiedusing a QIAquick PCR purification kit (QIAGEN) and were sequencedat the Advanced Genomic Analysis Center, University of Minnesota(Saint Paul, MN). Sequencing was performed in both directions withthe same primers as used in RT-PCR reactions. Sequences obtained werealigned with the existing database using BLAST search tool availableonline (www.ncbi.nlm.nih.gov).

RT-PCR for reovirus. Primers from the S4 gene, a nonstructuralprotein, were used for the detection of reovirus in the inoculum (Table 1).RNA from a known turkey reovirus (SEP 108; kindly provided by Dr. M.Day, Southeast Poultry Research Laboratory, Athens, GA) was used as apositive control. Amplification was carried out using a OneStep RT-PCRkit (QIAGEN). The reaction mix consisted of 13 RT-PCR reactionbuffer, 320 mM each dNTP, 0.6 mM each primer, 2 ml of enzyme blend,and 5 ml of extracted RNA for a total volume of 50 ml. Amplification stepsconsisted of reverse transcription at 50 C for 30 min; Taq activation at94 C for 15 min, followed by 35 cycles of denaturation at 94 C for30 sec, annealing at 53 C for 1 min, and extension at 72 C for 1 min;and a step of final extension at 72 C for 10 min. The PCR products were

518 N. Jindal et al.

gel electrophoresed and the position of the band (1120 bp) indicated viruspresence. For confirmation, PCR purified product from known positivecontrol was sequenced. The sequences were aligned with the existingdatabase using BLAST search tool.

Statistical analysis. To determine the effect of different treatmentson body weights and the interaction between treatment and age ofpoults, the data were analyzed statistically using the MIXED procedureof SAS, version 9.1 (SAS Institute, Inc., Cary, NC) at a significance levelof P , 0.05.

RESULTS

Clinical findings. Poults in groups A, B, and C started showingclinical signs of diarrhea from 2 DPI onward. Initially, the feces werewatery and frothy but later (from 33 DPI) changed to a semisolidconsistency. Poults given sediment suspension (group C) exhibitedmore watery and frothy feces and for a longer duration than thosegiven unfiltered supernatant (group A) or filtered supernatant (groupB). Some of the poults in groups A, B, and C were dull anddepressed between 3 and 10 DPI. No mortality was seen in any ofthe treated groups during the experiment. Poults in control group(group D) did not exhibit any signs of depression, lethargy, ordiarrhea during the course of the study.

Growth response. Data on body weight gain in birds of differentgroups at different intervals are presented in Table 2. In general, theweight gain was lower in the treated poults (groups A, B, and C)than in the control group (group D). Compared with the controlgroup (group D), birds in groups A, B, and C started showingsignificantly lower body weights from 10, 40, and 20 DPI,respectively. Poults treated with sediment suspension (group C)and unfiltered supernatant (group A) had a similar pattern of growthresponse, with no statistical difference at any interval. Althoughweight gain in birds of groups A and C was lower than in those ofgroup B at all intervals, the decrease was significant at 50 DPI andfrom 30 DPI, respectively.

When data from five intervals were averaged for each of the fourgroups for calculation of mean treatment effect on weight gain,significantly lower weight gain was detected in treated groups than inthe control group. Also, average weight gain in groups A and C wassignificantly lower than in group B. Percentage of weight loss ingroups A, B, and C compared with group D was 16%, 8%, and18%, respectively (Table 2), with an average overall growthdepression of 14% in the treated groups. Overall age 3 treatmentinteraction was significant.

Gross pathology. On necropsy, no gross changes were observedin poults of group D (control group). Gross changes, mostlyconfined to gastrointestinal tract, were observed in treated poults(groups A, B, and C) from 10 DPI onward. Pale distended intestineswith watery contents and distended ceca with loose to watery andfrothy contents were seen. When birds were opened at necropsy at10 DPI, greenish watery feces dripped from the vents of treated

poults. Similar changes were also noticed at 20 DPI, but the severitywas less. A few poults in group C revealed distended intestines at 30DPI but not thereafter. Cecal changes observed at 10 DPI werenoticed for up to 50 DPI in groups A and C but not in group B.Gross changes were more severe and involved a greater number ofbirds in group C than in groups A and B and correlated with theduration of diarrhea in treated poults. Poults given unfilteredsupernatant or sediment suspension revealed intestinal changes up to20 and 30 DPI, respectively. Poults in these groups also showeddiarrhea up to 26 and 33 DPI, respectively. Intestinal changes inpoults given filtered supernatant were observed for up to 20 DPI,and diarrhea in this group also lasted for 22 DPI.

Pathogen shedding. Rotavirus was detected in the inoculum byboth EM and RT-PCR, but astrovirus was detected only by RT-PCR. The data on shedding of these viruses in pooled intestinalcontents of treated poults are presented in Table 3. Rotavirus wasdetected in treated poults for up to 40 DPI, whereas astrovirus wasdetected only at 10 DPI in all three groups (groups A, B, and C).None of the pooled intestinal sample from group D was positive forrotavirus or astrovirus at any interval. Salmonella was isolated fromthe inoculum that belonged to serogroup E. No Salmonella wasisolated from treated poults at any intervals.

DISCUSSION

Observations of dullness and diarrhea in treated poults as early as2 DPI are consistent with our previous experiments (15). Similarresults were reported in rotavirus-inoculated turkey poults (40) andin poult malabsorption syndrome (26). Pantin-Jackwood et al. (23)also reported diarrhea, frothy feces, and depression in turkey poultsinoculated orally with TAstV-2. No mortality was observed in any ofthe groups, which is consistent with the results of our previous study(15) and with Yason and Schat (40) who did not observe anymortality in rotavirus-infected turkey poults. However, Brown et al.(5) and Guy et al. (12) have reported high mortality in turkeysinoculated with turkey coronavirus. These studies indicate thatmortality may depend on the pathogen involved.

Decreased body weight gains for up to 50 DPI in this study areconsistent with a decrease in body weights of turkey poults affectedwith poult enteritis complex (PEC) (2,5,7,27,32). In our previousstudy, we observed an average weight loss of 31.8% due to PES (15)compared with 14% in this study. This variation could be due tostrain(s), concentration, and virulence of the pathogen involved.However, even a 14% growth depression is economically significant.Barnes et al. (3) estimated that a 10%–15% growth depression dueto PEC would cause losses of US$300 and US$400 million annuallyto the U.S. turkey industry. Davis et al. (7) observed a 49% growthdepression in turkey poults inoculated with filtered intestine-pancreas homogenate obtained from spiking mortality of turkeys-affected turkey poults. Davis et al. (7) believed that this growth

Table 1. Primers used in the present study.

Virus Primer sequence Gene Reference

Rotavirus Forward: 59-GTGCGGAAAGATGGAGAAC-39 NSP4 Pantin-Jackwood et al. (24)Reverse: 59-GTTGGGGTACCAGGGATTAA-39

Astrovirus Forward: 59-AGCAGCAGTAGGTGGCAGTG-39 Capsid Koci et al. (16)Reverse: 59-TCATCATCCTCTCACACTGG-39

Reovirus Forward: 59-GTGCGTGTTGGAGTTTCCCG-39 S4 Pantin-Jackwood et al. (25)Reverse: 59-TACGCCATCCTAGCTGGA-39

Coronavirus Forward: 59-GGTAGCGGTGTTCCTGA-39 N Sellers et al. (34)Reverse: 59-CCCTCCTTACCTTTAGT-39

Effects of PES 519

depression was due to the presence of rotavirus, enterovirus-likevirus, birnavirus, and other undetected viruses present in thehomogenate.

The decrease in body weight gain can be attributed to decreasedfeed intake or altered feed conversion efficiency or both. It seemsthat infection with enteric viruses may decrease feed conversionefficiency, leading to lower weight gain in treated poults thatcontinues at a later stage also. Odetallah et al. (20) believed thatimpaired energy utilization and fat digestibility in PEMS were likelycontributors to stunted growth and reduced recovery rates. It hasbeen reported that the attainment of target weight was delayed instunted PEMS survivors and that severely affected survivors neverreached target market weight (9,20). We did not observe anycompensatory growth in any of the treated groups. Significantinteraction of treatment with age of poults indicated that themagnitude of the treatment effect was different depending on the ageat what the birds were euthanatized. In the present study, wemonitored turkey poults only for 50 DPI (9 wk of age) and did notobserve compensatory growth during this period, indicating thatthese birds may not attain an expected weight at market age, thusleading to considerable economic losses.

Gross changes noticed in the present study are consistent withthose reported in turkey poults affected with PEC(1,7,13,26,32,36,37). More severity in clinical signs, more depres-sion of growth and more pathology in sediment suspension-inoculated poults compared with unfiltered supernatant- and filteredsupernatant-treated poults may be due to the additive pathologiceffects of enteric viruses and Salmonella. More growth depression inpoults co-infected with turkey coronavirus and E. coli than poultsinfected with turkey coronavirus or E. coli has been reportedpreviously (12). The inoculum in this study was positive forrotavirus, astrovirus, and Salmonella and was negative for reovirusand coronavirus. Although the inoculum was positive for rotavirus,astrovirus, and Salmonella, the role of additional unidentifiedpathogens in the inoculum in causing and/or increasing the severityof PES cannot be ruled out. We did not attempt to characterize E.coli from PES cases; however, the enteropathogenic strains of E. colihave been reported from PEMS cases (22).

The shedding pattern of rotavirus indicated that this viruspersisted in the treated poults for up to 40 DPI. Rotavirus is amajor cause of diarrhea in humans and animals. This virus hasbeen detected in diarrheic turkeys (18,30,38) and in broilerchickens with runting and stunting syndrome (21). Astrovirus wasdetected only at 10 DPI. It is unclear why astroviruses were notdetected at later intervals. It is possible that the inoculum hadlower concentration of astrovirus to begin with. This finding is incontrast to our field observations in which we detected turkeyastrovirus in apparently healthy turkey breeder flocks for up to9 wk of age (Jindal, unpubl. data). Astroviruses are also importantcauses of diarrhea in humans and animals. McNulty et al. (19)identified turkey astroviruses for the first time from diarrheicpoults in the U.K. Subsequently, astroviruses were reported fromthe United States (17,28,30,31,32,33,41). We did not detectSalmonella in experimental poults, which may be due to lowconcentration of the pathogen in the inoculum, or to intermittentshedding of Salmonella. It has been reported that frequency ofintestinal colonization of Salmonella and its invasion of internalorgans is higher in newly hatched chicks compared with older birds(8,29). Barrow et al. (4) reported that Salmonella serotypescolonized in the gut when the infection was given within 2 days ofhatching, and there was no colonization when infected at 3 wk ofage. Therefore, age of inoculation of PES material (at 14 day of

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520 N. Jindal et al.

age) could be a factor for nonisolation of Salmonella in the presentstudy.

Under field conditions, the commercial poults are generally rearedon deep litter systems and the litter is not replaced during grow-outperiod. Buildup of microbial load (enteric viruses and bacteria) mayoccur during this time. A greater environmental load may help theseviruses to persist and also may increase the chances of fecal-oral routeof spread over time. Under such scenarios, adverse effects of greaterseverity may be expected. However, additional studies of a longerduration are required to know the shedding pattern of these virusesand their effect on body weight under field and experimentalconditions.

Thus, the present study reveals that oral inoculation of turkeypoults with PES material positive for rotavirus, astrovirus, andSalmonella leads to diarrhea and significant growth depression for upto 9 wk of age. There also may be additional implications for turkeygrowth beyond that time point—subsequent depression may resultin economic challenge to growers in the field.

REFERENCES

1. Ali, A., and D. L. Reynolds. Stunting syndrome in turkey poults.Isolation and identification of the etiologic agent. Avian Dis. 41:870–881.1997.

2. Angel, C. R., J. L. Sell, and D. W. Trampel. Stunting syndrome inturkeys. Development of an experimental model. Avian Dis. 34:447–453.1990.

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Table 3. Virus shedding (as detected by reverse transcription-PCR) in experimentally inoculated poults.

Virus GroupA

Virus shedding at DPIBC

10 20 30 40 50

Rotavirus A + 2 2 + 2B + 2 + + 2C 2 + 2 + 2D 2 2 2 2 2

Astrovirus A + 2 2 2 2B + 2 2 2 2C + 2 2 2 2D 2 2 2 2 2

AA 5 poults inoculated with unfiltered supernatant; B 5 poults inoculated with filtered supernatant; C 5 poults inoculated with sedimentsuspension; D 5 poults inoculated with phosphate-buffered saline (controls).

BDPI 5 days postinoculation.C+ 5 positive; 2 5 negative.

Effects of PES 521

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ACKNOWLEDGMENT

This work was funded in part with a research grant from RapidAgricultural Response Fund, University of Minnesota.

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