Infection and transmission dynamics of Turkey arthritis reovirus in different age Turkeys.

Turkey arthritis reovirus (TARV) has been established as a cause of lameness in meat type turkeys in the past decade. However, no information is available on the age susceptibility of TARV or its transmission dynamics. We conducted this study to determine the age at which turkey poults are susceptible to TARV infection and whether infected birds can horizontally transmit the virus to their non-infected pen mates (sentinels). Five groups of turkeys were orally inoculated with TARV (∼106 TCID50/ml) at 2, 7, 14, 21 and 28 days of age (DOA). Two days after each challenge, four uninfected sentinel turkeys of equal age were added to the virus-inoculated groups. At one- and two-weeks post infection, turkeys from each group, including two sentinels, were euthanized followed by necropsy. Inoculated birds in all age groups had TARV replication in the intestine and gastrocnemius tendon with no statistically significant variation at p < 0.5. Furthermore, the inoculated birds at different age groups showed consistently high gastrocnemius tendon histologic lesion scores while birds in the 28-days-old age group had numerically lower lesion scores at 14 days post inoculation (dpi). The sentinels, in turn, also showed virus replication in their intestines and tendons and histologic lesions in gastrocnemius tendons. The findings indicate that turkeys at the age of 28 days or less are susceptible to infection with TARV following oral challenge. It was also found that TARV-infected birds could transmit the infection to naïve sentinel turkeys of the same age.

Comparative pathogenesis of turkey reoviruses.

Turkey reoviruses have been implicated in multiple disease syndromes resulting in significant economic losses to the turkey industry. It has been known for decades that turkey enteric reovirus (TERV) is involved in poult enteritis complex, but turkey arthritis reovirus (TARV), the causative agent of tenosynovitis in turkeys, emerged in 2011. In 2019, we isolated reovirus from several cases of hepatitis in turkeys and tentatively named it turkey hepatitis reovirus (THRV). The comparative pathogenesis of these viruses, and correlation with their genetic make-up (if any), is not known. In this study, we inoculated nine groups of 1-week-old turkey poults with two THRV, five TARV and two TERV via oral route. A tenth group served as a negative control. A subset of birds from each group was euthanised at 3, 5, 7, 14, 21, and 28 days post-inoculation (dpi). Tissues were collected for histology and real-time RT-PCR. All nine viruses were found to be enterotropic; the virus gene copy number in the intestine reached a peak at 5 dpi followed by a sharp decline at 7 dpi. All viruses caused a significant decline in body weight gain of birds as compared to the negative control group. Both TARV and THRV strains replicated in tendons and produced histologic lesions consistent with tenosynovitis. Hepatic lesions were produced by THRV only and the virus was re-isolated from liver and spleen of inoculated birds fulfilling Koch's postulates. The results of this study should be helpful in facilitating diagnosis and designing future mitigation plans.

Genome characterization of Turkey Rotavirus G strains from the United States identifies potential recombination events with human Rotavirus B strains.

Rotavirus G (RVG) strains have been detected in a variety of avian species, but RVG genomes have been published from only a single pigeon and two chicken strains. Two turkey RVG strains were identified and characterized, one in a hatchery with no reported health issues and the other in a hatchery with high embryo/poult mortality. The two turkey RVG strains shared only an 85.3 % nucleotide sequence identity in the VP7 gene while the other genes possessed high nucleotide identity among them (96.3-99.9 %). Low nucleotide percentage identities (31.6-87.3 %) occurred among the pigeon and chicken RVG strains. Interestingly, potential recombination events were detected between our RVG strains and a human RVB strain, in the VP6 and NSP3 segments. The epidemiology of RVG in avian flocks and the pathogenicity of the two different RVG strains should be further investigated to understand the ecology and impact of RVG in commercial poultry flocks.

Experimentally induced lameness in turkeys inoculated with a newly emergent turkey reovirus.

Newly emergent turkey arthritis reoviruses (TARVs) have been isolated from cases of lameness in male turkeys over 10 weeks of age. In a previous study, experimental inoculation of TARV in one-week-old turkey poults produced lymphocytic tenosynovitis at four weeks post inoculation but without causing clinical lameness. This study was undertaken to determine if TARV infection at an early age can lead to clinical lameness in birds as they age. One-week-old male turkeys were inoculated orally with a TARV (strain TARV-O'Neil) and monitored for the development of gait defects until 16 weeks of age. At 4, 8, 12 and 16 weeks of age, a subset of birds was euthanized followed by the collection of gastrocnemius tendon, digital flexor tendon, and intestines for virus detection by rRT-PCR and for histologic inflammation scoring. Clinical lameness was first displayed in TARV-infected turkeys at 8 weeks of age and ruptured gastrocnemius tendons with progressive lameness were also seen at 12-16 weeks of age. The virus was detected in gastrocnemius tendon of 4- 8- and 12-week-old turkeys but not in 16-week-old turkeys. Histologic inflammation scores of tendons at each of the four time points were significantly higher in the virus-inoculated group than in the control group (p < 0.01). Lesions began as lymphocytic tenosynovitis with mild synoviocyte hyperplasia at four weeks of age and progressed to fibrosis as the birds aged. These results demonstrate the potential of TARV to infect young turkeys and to produce subclinical tenosynovitis that becomes clinically demonstrable as the turkeys age.

Efficacy of Five Commonly Used Disinfectants Against Turkey Arthritis Reovirus.

Since late 2009, an unusual problem of reovirus-related lameness has been seen in market-age tom turkeys in the upper Midwest area of the United States. In this study, we determined the efficacy of five commonly used disinfectants (Virocid, Keno X5, Synergize, One Stroke, and Tek Trol) against turkey arthritis reoviruses (TARVs). For comparison, turkey enteric reovirus (TERV) and chicken arthritis reovirus (CARV) were also included. At their recommended concentrations, all five disinfectants were found to be effective virucidals, inactivating 99.99% of all viruses within 10 min. However, oxidizing agents and quaternary ammonium compounds + aldehyde types of disinfectants were more effective, killing the viruses in a shorter time (2-5 min) than the other types of disinfectants. These results indicate that these disinfectants can be an effective tool in the control of these viruses.

Pathogenicity of newly emergent turkey arthritis reoviruses in chickens.

Turkey arthritis reoviruses (TARVs) were isolated recently from gastrocnemius and digital flexor tendons of lame turkeys with swollen joints and tenosynovitis. These TARVs were genetically different from chicken arthritis reoviruses (CARVs) and produced gastrocnemius tenosynovitis when inoculated into turkey poults. The purpose of this study was to determine the pathogenicity of TARVs in chickens. One-week-old, specific-pathogen-free chicks were inoculated with either a TARV (TARV-MN2 or TARV-O'Neil) or CARV via oral, intratracheal, or footpad routes. At 2 and 3 weeks post inoculation (PI), a subset of chicks from each group was euthanized followed by collection of tissues for real-time RT-PCR (rRT-PCR), virus isolation, and histopathology. Chickens inoculated with CARV via intratracheal and footpad routes developed gastrocnemius lymphocytic tenosynovitis at 2 and 3 weeks PI. Both TARV-MN2 and TARV-O'Neil induced gastrocnemius lymphocytic tenosynovitis in chicks inoculated only via the footpad route at 2 and 3 weeks PI. Although there was no evidence of clinical lameness, the virus was present in leg tendons, internal organs, and intestines of all TARV-inoculated chicks regardless of route of inoculation, as indicated by rRT-PCR and virus isolation. These results indicate that TARVs do not produce gastrocnemius tenosynovitis in chicks by 3 weeks PI when administered via the most probable natural route (e.g., oral and intratracheal). Further studies are needed to determine the long term effects these viruses might play in inducing lameness in chickens.

Survival of turkey arthritis reovirus in poultry litter and drinking water.

Turkey reoviruses (TRVs) can cause arthritis, tenosynovitis, and enteric diseases in turkeys, leading to huge economic losses. The TRVs are tentatively divided into turkey arthritis reoviruses (TARVs) and turkey enteric reoviruses (TERVs) depending on the type of disease they produce. This study was conducted to determine the survival of these viruses in autoclaved and nonautoclaved poultry litter and drinking water at room temperature (approx. 25°C). Three isolates of TARV (TARV-O'Neil, TARV-MN2, and TARV-MN4) and one each of TERV (TERV-MN1) and chicken arthritis reovirus (CARV) were used in this study. The viruses were propagated and titrated on QT-35 cells. In autoclaved dechlorinated tap water, all 5 viruses were able to survive for 9 to 13 wk. In nonautoclaved water, all 5 viruses survived for at least 2 wk. In autoclaved litter, the viruses survived for 6 to 8 wk, and in nonautoclaved litter, they survived for 6 to 8 d only. The implications of these results are discussed below.

The role of avian reoviruses in turkey tenosynovitis/arthritis.

Turkey arthritis reovirus (TARV) has been isolated from the gastrocnemius tendons and tibiotarsal joint fluid of lame male turkeys >12 weeks old in the Midwest. Two experiments were conducted to compare the pathogenicity in turkeys of three TARVs (TARV-MN2, TARV-MN4 and TARV-O'Neil), one turkey enteric reovirus (TERV strain MN1) and one chicken arthritis reovirus (CARV strain MN1). Two hundred microlitres of virus were inoculated by the oral, intratracheal, or footpad route into 6-day-old poults placed in isolator units. Poults were necropsied at 1 and 4 weeks post infection in Experiment 1, and at 2 and 4 weeks post infection in Experiment 2. Reovirus was detected by reverse transcription-polymerase chain reaction and virus isolation in tendons of TARV-inoculated poults at 1, 2 and 4 weeks post infection. TARV-O'Neil and TARV-MN2 were detected in tendons of sentinal birds at 1 and 4 weeks and 1 week p.i., respectively. In general, TARVs produced lymphocytic tenosynovitis of the gastrocnemius and digital flexor tendon sheaths without inflammation of the tendons proper. In Experiment 1, poults inoculated with TARV-MN2 and TARV-O'Neil had significantly higher gastrocnemius tendon inflammation scores, as determined by histology, than those inoculated with TERV-MN1 or CARV-MN1. In Experiment 2, poults inoculated with TARV-MN2 and TARV-O'Neil had significantly higher gastrocnemius tendon inflammation scores than those inoculated with TARV-MN4 and virus-free medium (negative control group). Koch's postulates was fulfilled when TARV-MN2 and TARV-O'Neil were re-isolated from tendons of poults that had originally been challenged with either of these viruses. Results of these experiments indicate that TARVs have a unique ability to induce gastrocnemius tenosynovitis in turkeys and that administration of TARV-O'Neil through the oral or intratracheal route is a reproducible model to study pathogenesis of TARV infection.

Detection and characterization of Newcastle disease virus in formalin-fixed, paraffin-embedded tissues from commercial broilers in Egypt.

Newcastle disease (ND) is highly contagious and causes severe economic losses to the poultry industry due to high morbidity and mortality. In this report, we describe the detection of Newcastle disease virus (NDV) in formalin-fixed tissues from an outbreak of ND on broiler farms in Egypt. The affected birds experienced respiratory and/or nervous signs and a 75% mortality rate. Tissue samples were collected and placed in 10% neutral buffered formalin followed by embedding in paraffin. RNA was extracted from 80-microm formalin-fixed paraffin-embedded tissue blocks and recovered in 60 microl of elution buffer. All samples were negative for influenza virus by real-time reverse-transcription (RT)-PCR but positive for NDV. These flocks were known to have been vaccinated with a live NDV vaccine (LaSota strain). The nucleic acid sequences of the virus detected in this study were similar to those of a velogenic virus at its cleavage site 111GRRQKR*F117 and clustered with class II genogroup VII lineage of NDV, with a nucleotide sequence identity of 94%-99%. Although extraction and amplification of NDV from paraffin-embedded tissues from experimentally infected birds has been reported previously, this study reports on the use of RT-PCR on formalin-fixed tissues from actual field samples.

One-step real-time reverse transcription-PCR for the detection of turkey reoviruses.

During late 2010 and early 2011, an unusual problem of lameness and swollen hock joints in commercial turkeys was reported in the upper Midwest, which continues to this day. The disease caused substantial economic losses to turkey producers. Reovirus was isolated from tendons and joint fluids of lame turkeys submitted to the Minnesota Veterinary Diagnostic Laboratory. This study was undertaken to develop a TaqMan real-time reverse transcription-PCR (rRT-PCR) assay for the early detection of turkey reoviruses (both enteric and lameness strains). A primer probe set was designed from the conserved region of the S4 segment of the turkey reovirus genome. The newly developed rRT-PCR was specific for the detection of turkey reoviruses. The detection limit of this assay was 10 genome copies per reaction. For the TARV-MN4 strain of turkey arthritis reovirus, one 50% tissue culture infectious dose was equivalent to 11.6 +/- 0.2 genome copies. The highest coefficient of variation for intraexperimental and interexperimental variability was 0.08 and 0.06, respectively, indicating the reproducibility of the assay. This new test should be useful for the detection of turkey enteric and arthritis reoviruses.

The occurrence of enteric viruses in Light Turkey Syndrome.

Two studies were conducted to determine the role of enteric viruses in Light Turkey Syndrome (LTS), which is characterized by lower weight in market age turkeys than their standard breed character. In the surveillance study, we selected four LTS and two non-LTS turkey flocks in Minnesota and collected faecal samples at 2, 3, 5 and 8-weeks of age. Astrovirus, rotavirus, and reovirus were detected alone or in various combinations in both LTS and non-LTS flocks. No coronavirus was detected in LTS flocks and no corona- or reovirus was detected in non-LTS flocks. In the second study, 2-week-old turkey poults were divided into two groups; Group A (challenged) was inoculated orally with 10% pooled faecal suspension from LTS flocks and group B (control) was inoculated with phosphate buffered saline (PBS). Clinical signs of depression, huddling, and lack of uniform size were observed in the challenged group but not in the control group. diarrhoea was observed in both groups but was more severe in the challenged group than in the control group. Birds in the challenged group shed astrovirus, rotavirus and reovirus, while the control group shed only astrovirus. Virus shedding in both groups was observed for up to nine weeks of age. Significantly lower body weights were seen in the challenged group starting at seven weeks of age and lasting until 20 weeks of age. These findings suggest that viral enteritis at an early age may set up conditions for the development of LTS in adult turkeys.

Isolation and characterization of a turkey arthritis reovirus.

During the spring and summer of 2011, the Minnesota Veterinary Diagnostic Laboratory at the University of Minnesota received 14 submissions of 15-to-18-week-old tom turkeys that were recumbent with wing tip bruises ("wing walkers") and uni- or bilateral swelling of the hock (tibiotarsal) joints. Gastrocnemius or digital flexor tendons were occasionally ruptured. A total of five turkey arthritis reoviruses (TARV-MN1 through TARV-MN5) were isolated in specific-pathogen-free embryonated chicken eggs and QT-35 cells. The identity of the isolates was confirmed by electron microscopy, reverse transcription-polymerase chain reaction, and gene sequence analysis. BLAST analysis on the basis of a 880 bp nucleotide sequence of the S4 gene confirmed all isolates as a reovirus. Phylogenetic analysis divided the five isolates into two subgroups: subgroup I containing TARV-MN1, -2, -3, and -5, and the other subgroup containing TARV-MN4. Isolates in subgroup I had a similarity of 97%-100% with each other, while subgroup II (TARV-MN4) had a similarity of only 89.2% with subgroup I viruses. This isolate showed 90%-93% similarity with turkey enteric reoviruses in the United States, while the other four isolates in subgroup I had 89%-97.6% similarity. These results indicate divergence within TARVs as well as from enteric viruses, which needs to be confirmed by complete genome sequence analysis. Further experimental studies are planned to determine the role of these isolates in turkey arthritis and to compare them with classical chicken reovirus.

Efficacy and Immunogenicity of Recombinant Pichinde Virus-Vectored Turkey Arthritis Reovirus Subunit Vaccine.

We created a recombinant live pichinde virus-vectored bivalent codon optimized subunit vaccine that expresses immunogenic Sigma C and Sigma B proteins of turkey arthritis reovirus. The vaccine virus could be transmitted horizontally immunizing the non-vaccinated pen mates. The vaccine was tested for efficacy against homologous (TARV SKM121) and heterologous (TARV O'Neil) virus challenge. Immunized poults produced serum neutralizing antibodies capable of neutralizing both viruses. The vaccinated and control birds showed similar body weights indicating no adverse effect on feed efficiency. Comparison of virus gene copy numbers in intestine and histologic lesion scores in tendons of vaccinated and non-vaccinated birds showed a decrease in the replication of challenge viruses in the intestine and tendons of vaccinated birds. These results indicate the potential usefulness of this vaccine.

An Outbreak of Fowl Aviadenovirus A-Associated Gizzard Erosion and Ulceration in Captive Bobwhite Quail (Colinus virginianus).

A flock of captive bobwhite quail (Colinus virginianus) experienced loose droppings, depression, and increased mortality starting at 3 wk of age. Necropsy of the affected birds revealed intestines dilated with frothy and tan fluid. Irregular dark brown fissures within the koilin layer of the gizzard were found in 20%-30% of the birds. Histologically, gizzards showed multifocal koilin degeneration or fragmentation, degeneration and necrosis of the subjacent epithelial cells, and infiltration of macrophages, lymphocytes, and heterophils. Necrotic epithelial cells occasionally contained large, smudgy, basophilic intranuclear inclusion bodies with marginated nuclear chromatin. Adenoviral paracrystalline arrays composed of icosahedral virions (60-70 nm diameter) were seen on transmission electron microscopy in the nuclei of epithelial cells in the gizzard mucosa. Adenovirus was isolated from gizzard, liver, intestine, and trachea by inoculation of specific-pathogen-free embryonated chicken eggs. Homogenates of the gizzard, liver, and intestine were positive for the adenovirus hexon gene by PCR. Sequencing of PCR amplicons confirmed the virus as fowl aviadenovirus A. The study isolates showed more than 99% and 97% nucleotide identity with quail bronchitis virus and with aviadenoviruses from gizzard erosion and ulceration (GEU) in broilers, respectively. The viral isolates showed six substitutions (G1T, C174A, A229G, C513A, T579A, and G621C) of which two were nonsynonymous (G1T and A229G), resulting in a change in the translated amino acid as A1S and S77G, respectively. These results indicate that adenoviruses of the same type or species can cause different clinical presentations in quails, e.g., bronchitis or GEU.

Artículo regular­Brote de erosiones y ulceraciones de la molleja asociadas con Aviadenovirus A del pollo en codornices de Virginia en cautiverio (Colinus virginianus). Una parvada de codornices de Virginia en cautiverio (Colinus virginianus) mostró heces acuosas, depresión y aumento de la mortalidad a partir de las tres semanas de edad. La necropsia de las aves afectadas reveló intestinos dilatados con líquido espumoso y marrón. Se encontraron fisuras irregulares de color marrón oscuro dentro de la capa de koilin de la molleja en el 20% al 30% de las aves. Histológicamente, las mollejas mostraron degeneración o fragmentación multifocal de la capa de koilin, degeneración y necrosis de las células epiteliales subyacentes e infiltración de macrófagos, linfocitos y heterófilos. Las células epiteliales necróticas contenían ocasionalmente cuerpos de inclusión intranucleares basófilos grandes, con cromatina nuclear marginada. Se observaron matrices paracristalinas adenovirales compuestas de viriones icosaédricos (60-70 nm de diámetro) en el microscopio electrónico de transmisión en los núcleos de las células epiteliales de la mucosa de la molleja. Se aisló adenovirus de molleja, hígado, intestino y tráquea mediante la inoculación de huevos embrionados de pollo libres de patógenos específicos. Los homogeneizados de la molleja, el hígado y el intestino fueron positivos para el gene del hexon del adenovirus por PCR. La secuenciación de amplicones de PCR confirmó la presencia de Aviadenovirus A del pollo. Los aislamientos del estudio mostraron una identidad mayor del 99% y 97% en la secuencia de nucleótidos con el virus de la bronquitis de codorniz y con aviadenovirus asociado con erosión y ulceración de mollejas (con las siglas en inglés GEU) en pollos de engorde, respectivamente. Los aislados virales mostraron seis sustituciones (G1T, C174A, A229G, C513A, T579A y G621C) de las cuales dos eran no-sinónimas (G1T y A229G), lo que resultó en un cambio en el aminoácido traducido como A1S y S77G, respectivamente. Estos resultados indican que los adenovirus del mismo tipo o especie pueden causar diferentes presentaciones clínicas en codornices, por ejemplo, bronquitis o erosión y ulceración de mollejas.

Development of a Recombinant Pichinde Virus-Vectored Vaccine against Turkey Arthritis Reovirus and Its Immunological Response Characterization in Vaccinated Animals.

Vaccination may be an effective way to reduce turkey arthritis reovirus (TARV)-induced lameness in turkey flocks. However, there are currently no commercial vaccines available against TARV infection. Here, we describe the use of reverse genetics technology to generate a recombinant Pichinde virus (PICV) that expresses the Sigma C and/or Sigma B proteins of TARV as antigens. Nine recombinant PICV-based TARV vaccines were developed carrying the wild-type S1 (Sigma C) and/or S3 (Sigma B) genes from three different TARV strains. In addition, three recombinant PICV-based TARV vaccines were produced carrying codon-optimized S1 and/or S3 genes of a TARV strain. The S1 and S3 genes and antigens were found to be expressed in virus-infected cells via reverse transcriptase polymerase chain reaction (RT-PCR) and the direct fluorescent antibody (DFA) technique, respectively. Turkey poults inoculated with the recombinant PICV-based TARV vaccine expressing the bivalent TARV S1 and S3 antigens developed high anti-TARV antibody titers, indicating the immunogenicity (and safety) of this vaccine. Future in vivo challenge studies using a turkey reovirus infection model will determine the optimum dose and protective efficacy of this recombinant virus-vectored candidate vaccine.

Enteric Viruses Associated with Mid-growth Turkey Enteritis.

Since August 2014, the University of Minnesota Veterinary Diagnostic Laboratory has received cases of turkey enteritis that are clinically different from previously described cases of poult enteritis syndrome and light turkey syndrome. The birds develop dark green and extremely foul-smelling diarrhea starting at 8-10 wk of age, which may last up to 15-16 wk of age. The affected turkey flocks show poor uniformity, and feed conversion and market weights are reduced. Multiple-age farms are affected more often than the single-age farms. Morbidity varies from flock to flock and in some cases reaches 100%. At necropsy, undigested feed with increased mucus is observed in the intestines along with prominent mucosal congestion and/or hemorrhage. Microscopically, lymphocytic infiltrates expand the villi in duodenum and jejunum to form lymphoid follicles, which are often accompanied by heterophils. Next generation sequencing (Illumina Miseq) on a pool of feces from affected birds identified genetic sequences of viruses belonging to Astroviridae, Reoviridae, Picornaviridae, Picobirnaviridae, and Adenoviridae. On testing pools of fecal samples from apparently healthy (16 pools) and affected birds (30 pools), there was a higher viral load in the feces of affected birds. Picobirnavirus was detected only in the affected birds; 20 of 30 pools (66.7%) were positive. These results indicate that a high viral load of turkey picobirnavirus alone, or in association with novel picornaviruses, may be a cause of this new type of turkey enteritis.

Experimental infection of Hawai'i 'Amakihi (hemignathus virens) with West Nile virus and competence of a co-occurring vector, culex quinquefasciatus: potential impacts on endemic Hawaiian avifauna.

Introduced mosquito-borne avian disease is a major limiting factor in the recovery and restoration of native Hawaiian forest birds. Annual epizootics of avian pox (Avipoxvirus) and avian malaria (Plasmodium relictum) likely led to the extinction of some species and continue to impact populations of susceptible Hawaiian honeycreepers (Drepanidinae). The introduction of a novel pathogen, such as West Nile virus (WNV), could result in further population declines and extinctions. During September and October 2004, we infected Hawai'i' Amakihi (Hemignathus virens) with a North American isolate of WNV by needle inoculation and mosquito bite to observe susceptibility, mortality, and illness in this endemic passerine, and to determine the vector competence of the co-occurring, introduced mosquito Culex quinquefasciatus. All experimentally infected Hawai'i ;Amakihi became viremic, with a mean titer >10(5) plaque-forming units (PFU)/ml, and they experienced clinical signs ranging from anorexia and lethargy to ataxia. The fatality rate among needle-inoculated Hawai'i' Amakihi (n=16) was 31.3%, but mortality in free-ranging birds is likely to increase due to predation, starvation, thermal stress, and concomitant infections of avian malaria and pox. Surviving Hawai'i' Amakihi seem to clear WNV from the peripheral blood by 7-10 days postinfection (DPI), and neutralizing antibodies were detected from 9 to 46 DPI. In transmission trials, Hawaiian Cx. quinquefasciatus proved to be a competent vector and Hawai'i Amakihi an adequate amplification host of WNV, suggesting that epizootic WNV could readily become an additional limiting factor of some native Hawaiian bird populations.

Retrospective Analysis of Turkey Arthritis Reovirus Diagnostic Submissions in Minnesota.

Turkey arthritis reovirus (TARV) causes tenosynovitis in turkeys, resulting in decreased profits for producers due to the increase in morbidity, mortality, and feed conversion ratio. There is limited information on TARV epidemiology, including the dynamics of diagnostic submissions to veterinary diagnostic laboratories. In this study, we retrospectively analyzed 719 cases of lameness in turkeys submitted to the Minnesota Veterinary Diagnostic Laboratory from March 2010 to May 2018. Almost all submissions were tendon pools, which were tested by virus isolation and/or real-time reverse transcription-polymerase chain reaction. Most of the submissions were from Minnesota. We found 52% of the submitted cases to be positive for TARV. The TARV-positive submissions increased considerably in the last few years. There was no statistical evidence that TARV diagnostic submissions were seasonal, although positive submissions were higher in January, April, July, and December. TARV-positive submissions also increased as flocks aged. In summary, we found that TARV submissions have increased in the last few years, have varied over time, and are correlated with age of the bird. This information is important guidance for conducting more studies to understand TARV infection dynamics.

Análisis retrospectivo de los casos de diagnóstico de artritis por reovirus en pavos en Minnesota. El reovirus de la artritis de los pavos (TARV) causa tenosinovitis en estas aves, lo que resulta en una disminución de las ganancias para los productores debido al aumento en la morbilidad, la mortalidad y la tasa de conversión alimenticia. Existe información limitada sobre la epidemiología del reovirus de los pavos, incluida la dinámica de los casos de diagnóstico enviados a los laboratorios de diagnóstico veterinario. En este estudio, se analizaron retrospectivamente 719 casos de cojeras en pavos enviados al Laboratorio de Diagnóstico Veterinario de Minnesota desde marzo del año 2010 hasta mayo del 2018. Casi todas los casos fueron muestras agrupadas de tendones, que se analizaron mediante aislamiento de virus y/o transcripción reversa y reacción en cadena de la polimerasa en tiempo real. La mayoría de los casos fueron de Minnesota. Se observó que el 52% de los casos presentados fueron positivos para reovirus de los pavos. Los casos positivos para artritis de los pavos por reovirus aumentaron considerablemente en los últimos años. No hubo evidencia estadística de que los casos de diagnóstico fueran estacionales, aunque los casos positivos fueron mayores en enero, abril, julio y diciembre. Las presentaciones positivas de la artritis de los pavos por reovirus también aumentaron a medida que las parvadas envejecían. En resumen, se observó que los casos de la artritis de los pavos por reovirus han aumentado en los últimos años, éstos han variado con el tiempo y están correlacionados con la edad del ave. Esta información es una guía importante para realizar más estudios para comprender la dinámica de la infección del reovirus causante de artritis en pavos.

Specific-pathogen-free Turkey model for reoviral arthritis.

Turkey arthritis reovirus (TARV) infections have been recognized since 2011 to cause disease and significant economic losses to the U.S. turkey industry. Reoviral arthritis has been reproduced in commercial-origin turkeys. However, determination of pathogenesis or vaccine efficacy in these turkeys can be complicated by enteric reovirus strains and other pathogens that ubiquitously exist at subclinical levels among commercial turkey flocks. In this study, turkeys from a specific-pathogen-free (SPF) flock were evaluated for use as a turkey reoviral arthritis model. One-day-old or 1-week-old poults were orally inoculated with TARV (O'Neil strain) and monitored for disease onset and progression. A gut isolate of turkey reovirus (MN1 strain) was also tested for comparison. Disease was observed only in TARV-infected birds. Features of reoviral arthritis in SPF turkeys included swelling of hock joints, tenosynovitis, distal tibiotarsal cartilage erosion, and gait defects (lameness). Moreover, TARV infection resulted in a significant depression of body weights during the early times post-infection. Age-dependent susceptibility to TARV infection was unclear. TARV was transmitted to all sentinel birds, which manifested high levels of tenosynovitis and tibiotarsal cartilage erosion. Simulation of stressful conditions by dexamethasone treatment did not affect the viral load or exacerbate the disease. Collectively, the clinical and pathological features of reoviral arthritis in the SPF turkey model generally resembled those induced in commercial turkeys under field and/or experimental conditions. The SPF turkey reoviral arthritis model will be instrumental in evaluation of TARV pathogenesis and reoviral vaccine efficacy.

Outbreak of highly pathogenic avian influenza in Minnesota in 2015.

The incursion of highly pathogenic avian influenza (HPAI) into the United States during 2014 resulted in an unprecedented foreign animal disease (FAD) event; 232 outbreaks were reported from 21 states. The disease affected 49.6 million birds and resulted in economic losses of $950 million. Minnesota is the largest turkey-producing state, accounting for 18% of U.S. turkey production. Areas with concentrated numbers of turkeys in Minnesota were the epicenter of the outbreak. The first case was presumptively diagnosed in the last week of February 2015 at the Minnesota Veterinary Diagnostic Laboratory (MVDL) and confirmed as HPAI H5N2 at the National Veterinary Services Laboratories on March 4, 2015. A total of 110 farms were affected in Minnesota, and the MVDL tested >17,000 samples from March to July 2015. Normal service was maintained to other clients of the laboratory during this major FAD event, but challenges were encountered with communications, staff burnout and fatigue, training requirements of volunteer technical staff, test kit validation, and management of specific pathogen-free egg requirements.