Characterizing the splice map of Turkey Hemorrhagic Enteritis Virus.

BACKGROUND: Hemorrhagic enteritis, caused by Turkey Hemorrhagic Enteritis Virus (THEV), is a disease affecting turkey poults characterized by immunosuppression and bloody diarrhea. An avirulent THEV strain that retains the immunosuppressive ability is used as a live vaccine. Characterizing the splice map of THEV is an essential step that would allow studies of individual genes mediating its immunosuppressive functions. We used RNA sequencing to characterize the splice map of THEV for the first time, providing key insights into the THEV gene expression and mRNA structures. METHODS: After infecting a turkey B-cell line with the vaccine strain, samples in triplicates were collected at 4-, 12-, 24-, and 72-hours post-infection. Total RNA was extracted, and poly-A-tailed mRNA sequenced. Reads were mapped to the THEV genome after trimming and transcripts assembled with StringTie. We performed PCR of THEV cDNA, cloned the PCR products, and used Sanger sequencing to validate all identified splice junctions. RESULTS: Researchers previously annotated the THEV genome as encoding 23 open reading frames (ORFs). We identified 29 spliced transcripts from our RNA sequencing data, all containing novel exons although some exons matched some previously annotated ORFs. The three annotated splice junctions were also corroborated by our data. During validation we identified five additional unique transcripts, a subset of which were further validated by 3' rapid amplification of cDNA ends (3' RACE). Thus, we report that the genome of THEV contains 34 transcripts with the coding capacity for all annotated ORFs. However, we found six of the previously annotated ORFs to be truncated ORFs on the basis of the identification of an in-frame upstream start codon or the detection of additional coding exons. We also identified three of the annotated ORFs with longer or shorter isoforms, and seven novel unannotated ORFs that could potentially be translated; although it is beyond the scope of this manuscript to investigate whether they are translated. CONCLUSIONS: Similar to human adenoviruses, all THEV transcripts are spliced and organized into five transcription units under the control of their cognate promoters. The genes are expressed under temporal regulation and THEV also produces multiple distinctly spliced transcripts that code for the same protein. Studies of the newly identified potential proteins should be urgently performed as these proteins may have roles in THEV-induced immunosuppression. Also, knowing the splicing of THEV genes should be invaluable to future research focusing on studying THEV genes, as this will allow accurate cloning of the mRNAs.

In turkeys, unlike chickens, the non-structural NS1 protein does not play a significant role in the replication and tissue tropism of the H7N1 avian influenza virus.

The economic losses caused by high pathogenicity (HP) avian influenza viruses (AIV) in the poultry industry worldwide are enormous. Although chickens and turkeys are closely related Galliformes, turkeys are thought to be a bridging host for the adaptation of AIV from wild birds to poultry because of their high susceptibility to AIV infections. HPAIV evolve from low pathogenicity (LP) AIV after circulation in poultry through mutations in different viral proteins, including the non-structural protein (NS1), a major interferon (IFN) antagonist of AIV. At present, it is largely unknown whether the virulence determinants of HPAIV are the same in turkeys and chickens. Previously, we showed that mutations in the NS1 of HPAIV H7N1 significantly reduced viral replication in chickens in vitro and in vivo. Here, we investigated the effect of NS1 on the replication and virulence of HPAIV H7N1 in turkeys after inoculation with recombinant H7N1 carrying a naturally truncated wild-type NS1 (with 224 amino-acid "aa" in length) or an extended NS1 with 230-aa similar to the LP H7N1 ancestor. There were no significant differences in multiple-cycle viral replication or in the efficiency of NS1 in blocking IFN induction in the cell culture. Similarly, all viruses were highly virulent in turkeys and replicated at similar levels in various organs and swabs collected from the inoculated turkeys. These results suggest that NS1 does not play a role in the virulence or replication of HPAIV H7N1 in turkeys and further indicate that the genetic determinants of HPAIV differ in these two closely related galliform species.

Evaluating the epizootic and zoonotic threat of an H7N9 low-pathogenicity avian influenza virus (LPAIV) variant associated with enhanced pathogenicity in turkeys.

Between 2013 and 2017, the A/Anhui/1/13-lineage (H7N9) low-pathogenicity avian influenza virus (LPAIV) was epizootic in chickens in China, causing mild disease, with 616 fatal human cases. Despite poultry vaccination, H7N9 has not been eradicated. Previously, we demonstrated increased pathogenesis in turkeys infected with H7N9, correlating with the emergence of the L217Q (L226Q H3 numbering) polymorphism in the haemagglutinin (HA) protein. A Q217-containing virus also arose and is now dominant in China following vaccination. We compared infection and transmission of this Q217-containing 'turkey-adapted' (ty-ad) isolate alongside the H7N9 (L217) wild-type (wt) virus in different poultry species and investigated the zoonotic potential in the ferret model. Both wt and ty-ad viruses demonstrated similar shedding and transmission in turkeys and chickens. However, the ty-ad virus was significantly more pathogenic than the wt virus in turkeys but not in chickens, causing 100 and 33% mortality in turkeys respectively. Expanded tissue tropism was seen for the ty-ad virus in turkeys but not in chickens, yet the viral cell receptor distribution was broadly similar in the visceral organs of both species. The ty-ad virus required exogenous trypsin for in vitro replication yet had increased replication in primary avian cells. Replication was comparable in mammalian cells, and the ty-ad virus replicated successfully in ferrets. The L217Q polymorphism also affected antigenicity. Therefore, H7N9 infection in turkeys can generate novel variants with increased risk through altered pathogenicity and potential HA antigenic escape. These findings emphasize the requirement for enhanced surveillance and understanding of A/Anhui/1/13-lineage viruses and their risk to different species.

Pathological and phylogenetic characterization of a rare fowl adenovirus (FAdV-8b) associated with inclusion body hepatitis in naturally infected Meleagris gallopavo.

Adenoviruses are a diverse group of viruses that can cause a variety of diseases in poultry, including respiratory and gastrointestinal infections. In turkeys (Meleagris gallopavo), adenoviruses commonly cause hemorrhagic enteritis and, rarely, inclusion body hepatitis. In this study, we investigated fowl adenoviruses (FAdVs) circulating in turkeys in Egypt. Following clinical examination of 500 birds, a portion of the hexon gene was amplified from four out of 50 samples from diseased birds (8%), and one amplicon that produced a strong band was selected for sequencing. Molecular and phylogenetic analysis revealed that the virus in that sample belonged to serotype FAdV-8b. Histopathological and immunohistochemical examinations of prepared tissue sections were performed to confirm the pathological findings. Diseased birds exhibited ruffled feathers, low body weight, a crouching posture, and diarrhea. Gross examination revealed petechial hemorrhage on the spleen, swollen pale liver, and congested intestine. Microscopic examination revealed the presence of eosinophilic and basophilic intranuclear inclusion bodies, nuclear pyknosis, and apoptotic bodies in the liver, congestion, hemorrhage, and fibrosis in the lungs, and desquamation of enterocytes. The presence of viral antigens in the liver, lungs, and intestine was confirmed by immunohistochemistry. To our knowledge, this is the first report of the characterization of an outbreak of inclusion body hepatitis in turkeys (hybrid converter breeds) due to FAdV-8b in Egypt. This finding raises an epidemiological alarm, necessitating further studies, including full-genome sequencing, to trace the virus's origin and genetic diversity.

Infection dynamics of subtype H9N2 low pathogenic avian influenza a virus in turkeys.

While mammals can be infected by influenza A virus either sporadically or with well adapted lineages, aquatic birds are the natural reservoir of the pathogen. So far most of the knowledge on influenza virus dynamics was however gained on mammalian models. In this study, we infected turkeys using a low pathogenic avian influenza virus and determined the infection dynamics with a target-cell limited model. Results showed that turkeys had a different set of infection characteristics, compared with humans and ponies. The viral clearance rates were similar between turkeys and ponies but higher than that in humans. The cell death rates and cell to cell transmission rates were similar between turkeys and humans but higher than those in ponies. Overall, this study indicated the variations of within-host dynamics of influenza infection in avian, humans, and other mammalian systems.

Analysis of Emerging Variants of Turkey Reovirus using Machine Learning.

Avian reoviruses continue to cause disease in turkeys with varied pathogenicity and tissue tropism. Turkey enteric reovirus has been identified as a causative agent of enteritis or inapparent infections in turkeys. The new emerging variants of turkey reovirus, tentatively named turkey arthritis reovirus (TARV) and turkey hepatitis reovirus (THRV), are linked to tenosynovitis/arthritis and hepatitis, respectively. Turkey arthritis and hepatitis reoviruses are causing significant economic losses to the turkey industry. These infections can lead to poor weight gain, uneven growth, poor feed conversion, increased morbidity and mortality and reduced marketability of commercial turkeys. To combat these issues, detecting and classifying the types of reoviruses in turkey populations is essential. This research aims to employ clustering methods, specifically K-means and Hierarchical clustering, to differentiate three types of turkey reoviruses and identify novel emerging variants. Additionally, it focuses on classifying variants of turkey reoviruses by leveraging various machine learning algorithms such as Support Vector Machines, Naive Bayes, Random Forest, Decision Tree, and deep learning algorithms, including convolutional neural networks (CNNs). The experiments use real turkey reovirus sequence data, allowing for robust analysis and evaluation of the proposed methods. The results indicate that machine learning methods achieve an average accuracy of 92%, F1-Macro of 93% and F1-Weighted of 92% scores in classifying reovirus types. In contrast, the CNN model demonstrates an average accuracy of 85%, F1-Macro of 71% and F1-Weighted of 84% scores in the same classification task. The superior performance of the machine learning classifiers provides valuable insights into reovirus evolution and mutation, aiding in detecting emerging variants of pathogenic TARVs and THRVs.

Pathological and phylogenetic characteristics of fowl AOAV-1 and H5 isolated from naturally infected Meleagris Gallopavo.

BACKGROUND: In this study, we investigated the prevalence of respiratory viruses in four Hybrid Converter Turkey (Meleagris gallopavo) farms in Egypt. The infected birds displayed severe respiratory signs, accompanied by high mortality rates, suggesting viral infections. Five representative samples from each farm were pooled and tested for H5 & H9 subtypes of avian influenza viruses (AIVs), Avian Orthoavulavirus-1 (AOAV-1), and turkey rhinotracheitis (TRT) using real-time RT-PCR and conventional RT-PCR. Representative tissue samples from positive cases were subjected to histopathology and immunohistochemistry (IHC). RESULTS: The PCR techniques confirmed the presence of AOAV-1 and H5 AIV genes, while none of the tested samples were positive for H9 or TRT. Microscopic examination of tissue samples revealed congestion and hemorrhage in the lungs, liver, and intestines with leukocytic infiltration. IHC revealed viral antigens in the lungs, liver, and intestines. Phylogenetic analysis revealed that H5 HA belonged to 2.3.4.4b H5 sublineage and AOAV-1 belonged to VII 1.1 genotype. CONCLUSIONS: The study highlights the need for proper monitoring of hybrid converter breeds for viral diseases, and the importance of vaccination programs to prevent unnecessary losses. To our knowledge, this is the first study that reports the isolation of AOAV-1 and H5Nx viruses from Hybrid Converter Turkeys in Egypt.

Geographical Expansion of Avian Metapneumovirus Subtype B: First Detection and Molecular Characterization of Avian Metapneumovirus Subtype B in US Poultry.

Avian metapneumovirus (aMPV), classified within the Pneumoviridae family, wreaks havoc on poultry health. It typically causes upper respiratory tract and reproductive tract infections, mainly in turkeys, chickens, and ducks. Four subtypes of AMPV (A, B, C, D) and two unclassified subtypes have been identified, of which subtypes A and B are widely distributed across the world. In January 2024, an outbreak of severe respiratory disease occurred on turkey and chicken farms across different states in the US. Metagenomics sequencing of selected tissue and swab samples confirmed the presence of aMPV subtype B. Subsequently, all samples were screened using an aMPV subtype A and B multiplex real-time RT-PCR kit. Of the 221 farms, 124 (56%) were found to be positive for aMPV-B. All samples were negative for subtype A. Six whole genomes were assembled, five from turkeys and one from chickens; all six assembled genomes showed 99.29 to 99.98% nucleotide identity, indicating a clonal expansion event for aMPV-B within the country. In addition, all six sequences showed 97.74 to 98.58% nucleotide identity with previously reported subtype B sequences, e.g., VCO3/60616, Hungary/657/4, and BR/1890/E1/19. In comparison to these two reference strains, the study sequences showed unique 49-62 amino acid changes across the genome, with maximum changes in glycoprotein (G). One unique AA change from T (Threonine) to I (Isoleucine) at position 153 in G protein was reported only in the chicken aMPV sequence, which differentiated it from turkey sequences. The twelve unique AA changes along with change in polarity of the G protein may indicate that these unique changes played a role in the adaptation of this virus in the US poultry. This is the first documented report of aMPV subtype B in US poultry, highlighting the need for further investigations into its genotypic characterization, pathogenesis, and evolutionary dynamics.

Experimental infection of domestic turkeys with lymphoproliferative disease virus of North American origin.

Lymphoproliferative disease virus (LPDV) was first documented in wild turkeys in North America in 2009. LPDV infection is often subclinical but can manifest as lymphoid proliferation or round cell neoplasia. Despite high prevalence across many sampled areas corresponding to declining populations of wild turkeys, knowledge regarding LPDV pathogenesis, risk factors for disease development, and associated impacts on population dynamics are unknown. To understand transmission, viral shedding, and tissue tropism, we inoculated 21 domestic turkeys via the oral cavity, crop, nasal cavity, subcutis, or coelomic cavity. For 12 weeks, oropharyngeal swabs, cloacal swabs, and whole blood were collected weekly. At 1 week postinoculation, 3 turkeys (3/21; 14%) had detectable LPDV proviral DNA in blood by polymerase chain reaction, and 10 developed DNAemia (50%; 10/20) by 12 weeks. LPDV proviral DNA was intermittently detected in oropharyngeal and cloacal swabs. Splenomegaly was the most consistent gross finding in DNAemic birds (8/11; 73%). Lymphoid hyperplasia in the spleen was the most significant microscopic finding (9/11; 82%). Three turkeys (3/11; 27%) developed round cell neoplasia characterized by sheets of pleomorphic, round to polygonal cells in the adrenal gland, bone marrow, skin, small intestine, and/or spleen. LPDV was detected in the spleen and bone marrow from all turkeys with DNAemia and all neoplasms. Our study establishes that infection and disease with North American LPDV from wild turkeys can be experimentally reproduced in domestic turkeys, laying the groundwork for future investigations into LPDV pathogenesis, development of diagnostic techniques, and understanding the impacts of LPDV on wild turkey populations.

Occurrence of enteric viruses causing clinical diarrhea in small ruminants in northern Indian plains: a reverse transcription PCR based molecular study.

Fowlpox virus (FPV) infects chickens and turkeys giving rise to pock lesions on various body parts like combs, wattles, legs, shanks, eyes, mouth, etc. The birds, affected with FPV, also show anemia and a ruffled appearance which are clinical symptoms of reticuloendotheliosis. Interestingly, the field strains of FPV are integrated with the provirus of reticuloendotheliosis virus (REV). Due to this integration, the infected birds, upon replication of FPV, give rise to free REV virions, causing severe immunosuppression and anemia. Pox scabs, collected from the infected birds, not only show positive PCR results upon performing FPV-specific 4b core protein gene PCR but also show positive results for the PCR of REV-specific env gene and FPV-REV 5'LTR junction. Homogenized suspension of the pock lesions, upon inoculating to the chorio-allantoic membrane (CAM) of 10-day-old specific pathogen-free embryonated chicken eggs, produces characteristic pock lesions in serial passages. However, the lesions also harbor REV mRNA or free virion, which can be identified by performing REV-specific env gene PCR using REV RNA from FPV-infected CAMs. The study suggests successful replication and availability of REV mRNA and free virion alongside the FPV, although the CAM is an ill-suited medium for any retroviral (like REV) growth and replication.

Evidence for Different Virulence Determinants and Host Response after Infection of Turkeys and Chickens with Highly Pathogenic H7N1 Avian Influenza Virus.

Wild birds are the reservoir for all avian influenza viruses (AIV). In poultry, the transition from low pathogenic (LP) AIV of H5 and H7 subtypes to highly pathogenic (HP) AIV is accompanied mainly by changing the hemagglutinin (HA) monobasic cleavage site (CS) to a polybasic motif (pCS). Galliformes, including turkeys and chickens, succumb with high morbidity and mortality to HPAIV infections, although turkeys appear more vulnerable than chickens. Surprisingly, the genetic determinants for virulence and pathogenesis of HPAIV in turkeys are largely unknown. Here, we determined the genetic markers for virulence and transmission of HPAIV H7N1 in turkeys, and we explored the host responses in this species compared to those of chickens. We found that recombinant LPAIV H7N1 carrying pCS was avirulent in chickens but exhibited high virulence in turkeys, indicating that virulence determinants vary in these two galliform species. A transcriptome analysis indicated that turkeys mount a different host response than do chickens, particularly from genes involved in RNA metabolism and the immune response. Furthermore, we found that the HA glycosylation at residue 123, acquired by LP viruses shortly after transmission from wild birds and preceding the transition from LP to HP, had a role in virus fitness and virulence in chickens, though it was not a prerequisite for high virulence in turkeys. Together, these findings indicate variable virulence determinants and host responses in two closely related galliformes, turkeys and chickens, after infection with HPAIV H7N1. These results could explain the higher vulnerability to HPAIV of turkeys compared to chickens. IMPORTANCE Infection with HPAIV in chickens and turkeys, two closely related galliform species, results in severe disease and death. Although the presence of a polybasic cleavage site (pCS) in the hemagglutinin of AIV is a major virulence determinant for the transition of LPAIV to HPAIV, there are knowledge gaps on the genetic determinants (including pCS) and the host responses in turkeys compared to chickens. Here, we found that the pCS alone was sufficient for the transformation of a LP H7N1 into a HPAIV in turkeys but not in chickens. We also noticed that turkeys exhibited a different host response to an HPAIV infection, namely, a widespread downregulation of host gene expression associated with protein synthesis and the immune response. These results are important for a better understanding of the evolution of HPAIV from LPAIV and of the different outcomes and the pathomechanisms of HPAIV infections in chickens and turkeys.

First report of Serotype-1 Marek's disease virus (MDV-1) with oncogenic form in backyard turkeys in Turkey: a molecular analysis study.

BACKGROUND: Marek's disease (MD) is a lymphoproliferative disease caused by Gallid alphaherpesvirus 2 (GaHV-2, MDV-1), which primarily affects chickens. However, the virus is also able to induce tumors and polyneuritis in turkeys, albeit less frequently than in chickens. RESULTS: This is the first study in Turkey reporting the molecular characterization of a MDV-1 strain detected in a flock of backyard turkeys exhibiting visceral lymphoma. Here, MEQ, vIL-8, pp38 and 132-bp tandem repeat regions, which are frequently preferred in the pathotyping of MDV-1, were examined. It was determined that the MEQ gene of MDV-1/TR-21/turkey strain obtained in the present study encoded 339 amino acids (1020 nt) and had four proline-rich repeat regions (PPPP). Based on the nucleotide sequence of the MEQ gene of the MDV-1/TR-21/turkey strain, a phylogenetic tree was created using the MEGA-X software with the Maximum Likelihood Method (in 1000 replicates). Our strain was highly identical (> 99.8) to the Italian/Ck/625/16, Polish (Polen5) and some Turkish (Layer-GaHV-2-02-TR-2017, Tr/MDV-1/19) MDV-1 strains. Also, nt and aa sequences of the MEQ gene of our strain were 99.1 and 99.41% identical to another Turkish strain (MDV/Tur/2019) originated from chickens. Sequence analysis of pp38 and vIL-8 genes also supported the above finding. The identity ratios of nucleotide and amino acid sequences of vIL-8 and pp38 genes of MDV-1/TR-21/turkey strain were 99.64-100% and 99.79-100%, respectively, when compared with those of the Polish strain. According to 132-bp tandem repeat PCR results, the MDV-1/TR-21/turkey strain had five copies. CONCLUSIONS: These results suggested that the MDV-1/TR-21/turkey strain obtained from backyard turkeys can be either very virulent or very virulent plus pathotype, though experimental inoculation is required for precise pathotyping.

Simulated Flock-Level Shedding Characteristics of Turkeys in Ten Thousand Bird Houses Infected with H7 Low Pathogenicity Avian Influenza Virus Strains.

Understanding the amount of virus shed at the flock level by birds infected with low pathogenicity avian influenza virus (LPAIV) over time can help inform the type and timing of activities performed in response to a confirmed LPAIV-positive premises. To this end, we developed a mathematical model which allows us to estimate viral shedding by 10,000 turkey toms raised in commercial turkey production in the United States, and infected by H7 LPAIV strains. We simulated the amount of virus shed orally and from the cloaca over time, as well as the amount of virus in manure. In addition, we simulated the threshold cycle value (Ct) of pooled oropharyngeal swabs from birds in the infected flock tested by real-time reverse transcription polymerase chain reaction. The simulation model predicted that little to no shedding would occur once the highest threshold of seroconversion was reached. Substantial amounts of virus in manure (median 1.5×108 and 5.8×109; 50% egg infectious dose) were predicted at the peak. Lastly, the model results suggested that higher Ct values, indicating less viral shedding, are more likely to be observed later in the infection process as the flock approaches recovery.

The Pathobiology of H7N3 Low and High Pathogenicity Avian Influenza Viruses from the United States Outbreak in 2020 Differs between Turkeys and Chickens.

An outbreak caused by H7N3 low pathogenicity avian influenza virus (LPAIV) occurred in commercial turkey farms in the states of North Carolina (NC) and South Carolina (SC), United States in March of 2020. Subsequently, H7N3 high pathogenicity avian influenza virus (HPAIV) was detected on a turkey farm in SC. The infectivity, transmissibility, and pathogenicity of the H7N3 HPAIV and two LPAIV isolates, including one with a deletion in the neuraminidase (NA) protein stalk, were studied in turkeys and chickens. High infectivity [<2 log10 50% bird infectious dose (BID50)] and transmission to birds exposed by direct contact were observed with the HPAIV in turkeys. In contrast, the HPAIV dose to infect chickens was higher than for turkeys (3.7 log10 BID50), and no transmission was observed. Similarly, higher infectivity (<2-2.5 log10 BID50) and transmissibility were observed with the H7N3 LPAIVs in turkeys compared to chickens, which required higher virus doses to become infected (5.4-5.7 log10 BID50). The LPAIV with the NA stalk deletion was more infectious in turkeys but did not have enhanced infectivity in chickens. These results show clear differences in the pathobiology of AIVs in turkeys and chickens and corroborate the high susceptibility of turkeys to both LPAIV and HPAIV infections.

A histopathological and immunohistochemical study of experimental infected turkeys with a virulent Newcastle disease virus.

Newcastle disease (ND) is a highly contagious infection of many avian species, mainly chickens and turkeys, with a devastating impact on worldwide poultry production. This study was designed to examine the effect of virulent ND infection in turkey's tissues and the tissue tropism of the virus. During the previous study period, poults were inoculated at 32 days of age with 105 EID50 virulent Newcastle disease virus. Three poults on days 0, 1, 2, 3, 4, 6, 7, and 14 postinoculations (PI) were selected from each group. They were euthanized by intravenous sodium pentobarbital injection. After macroscopic observation, to histopathological and immunohistochemical studies, the spleen, bursa, cecal tonsils, intestine, proventriculus, lung, kidney, and brain were sampled. Clinically, the infected turkeys exhibited loss of appetite, severe depression, down on hock joint, white to greenish (sometimes bloody) diarrhea, nervous signs, and mild respiratory problems. Out of 45 birds inoculated, 9 (20%) died. Histopathological effects in lymphoid tissues included necrosis and penetration of mononuclear cells on day 4 PI, and subsequent follicular lymphoid depletion on days 6 and 8 PI was observed. Based on the immunohistochemical test, on day 3 in cecal tonsils and spleen, and on day 8 PI, all of them were positive for virus antigen. In conclusion, the NDV circulating in Iranian chicken flocks has the potential to cause severe illness in commercial turkeys.

The Requirement of Glycoprotein C for Interindividual Spread Is Functionally Conserved within the Alphaherpesvirus Genus (Mardivirus), but Not the Host (Gallid).

Marek's disease (MD) in chickens is caused by Gallid alphaherpesvirus 2, better known as MD herpesvirus (MDV). Current vaccines do not block interindividual spread from chicken-to-chicken, therefore, understanding MDV interindividual spread provides important information for the development of potential therapies to protect against MD, while also providing a natural host to study herpesvirus dissemination. It has long been thought that glycoprotein C (gC) of alphaherpesviruses evolved with their host based on their ability to bind and inhibit complement in a species-selective manner. Here, we tested the functional importance of gC during interindividual spread and host specificity using the natural model system of MDV in chickens through classical compensation experiments. By exchanging MDV gC with another chicken alphaherpesvirus (Gallid alphaherpesvirus 1 or infectious laryngotracheitis virus; ILTV) gC, we determined that ILTV gC could not compensate for MDV gC during interindividual spread. In contrast, exchanging turkey herpesvirus (Meleagrid alphaherpesvirus 1 or HVT) gC could compensate for chicken MDV gC. Both ILTV and MDV are Gallid alphaherpesviruses; however, ILTV is a member of the Iltovirus genus, while MDV is classified as a Mardivirus along with HVT. These results suggest that gC is functionally conserved based on the virus genera (Mardivirus vs. Iltovirus) and not the host (Gallid vs. Meleagrid).

Pathogenic evaluation of a turkey coronavirus isolate (TCoV NC1743) in turkey poults for establishing a TCoV disease model.

Turkey coronavirus (TCoV) can cause a highly contagious enteric disease in turkeys with severe economic losses in the global turkey industry. To date, no commercial vaccines are available for control of the disease. In the present study, we isolated a field strain (NC1743) of TCoV and evaluated its pathogenicity in specific-pathogen-free (SPF) turkey poults to establish a TCoV disease model. The results showed that the TCoV NC1743 isolate was pathogenic to turkey poults with a minimal infectious dose at 106 EID50/bird. About 50 % of one-day-old SPF turkeys infected with the virus's minimal infectious dose exhibited typical enteric disease signs and lesions from 6 days post-infection (dpi) to the end of the experiment (21 dpi). In contrast, fewer than 20 % of older turkeys (1- or 2-week-old) infected with the same amount of TCoV displayed enteric disease signs, which disappeared after 15-18 dpi. Although all infected turkeys, regardless of age, shed TCoV, the older turkeys shed less virus than the younger birds, and 50 % of the 2-week-old birds even cleared the virus at 21 dpi. Furthermore, the viral infection caused day-old turkeys more body-weight-gain reduction than older birds. The overall data demonstrated that the TCoV NC1743 isolate is a highly pathogenic strain and younger turkeys are more susceptible to TCoV infection than older birds. Thus, one-day-old turkeys infected with the minimal infectious dose of TCoV NC1743 could be used as a TCoV disease model to study the disease pathogenesis, and the TCoV NC1743 strain could be used as a challenge virus to evaluate a vaccine protective efficacy.

Biodetection of a specific odor signature in mallard feces associated with infection by low pathogenic avian influenza A virus.

Outbreaks of avian influenza virus (AIV) infection included the spread of highly pathogenic AIV in commercial poultry and backyard flocks in the spring of 2015. This resulted in estimated losses of more than $8.5 million from federal government expenditures, $1.6 billion from direct losses to produces arising from destroyed turkey and chicken egg production, and economy-wide indirect costs of $3.3 billion from impacts on retailers and the food service industries. Additionally, these outbreaks resulted in the death or depopulation of nearly 50 million domestic birds. Domesticated male ferrets (Mustela putorius furo) were trained to display a specific conditioned behavior (i.e. active scratch alert) in response to feces from AIV-infected mallards in comparison to feces from healthy ducks. In order to establish that ferrets were identifying samples based on odors associated with infection, additional experiments controlled for potentially confounding effects, such as: individual duck identity, housing and feed, inoculation concentration, and day of sample collection (post-infection). A final experiment revealed that trained ferrets could detect AIV infection status even in the presence of samples from mallards inoculated with Newcastle disease virus or infectious laryngotracheitis virus. These results indicate that mammalian biodetectors are capable of discriminating the specific odors emitted from the feces of non-infected versus AIV infected mallards, suggesting that the health status of waterfowl can be evaluated non-invasively for AIV infection via monitoring of volatile fecal metabolites. Furthermore, in situ monitoring using trained biodetectors may be an effective tool for assessing population health.

Highly pathogenic avian influenza virus H5N6 (clade 2.3.4.4b) has a preferable host tropism for waterfowl reflected in its inefficient transmission to terrestrial poultry.

Highly-pathogenic avian influenza virus (HPAIV) H5N6 (clade 2.3.4.4b) incurred into Europe in late 2017 and was predominantly detected in wild birds, with very few terrestrial poultry cases. Pekin ducks directly-infected with a UK virus (H5N6-2017) were donors of infection to investigate contact transmission to three recipient species: Ducks, chickens and turkeys. H5N6-2017 transmission to ducks was 100% efficient, but transmission to in-contact galliforme species was infrequent and unpredictable, thereby reflecting the European 2017-2018 H5N6 epidemiology. Although only two of 28 (7%) infected ducks died, the six turkeys and one chicken which became infected all died and displayed systemic H5N6-2017 dissemination, while pathogenesis in ducks was generally milder. Analysis of H5N6-2017 progeny in the contacts revealed no emergent polymorphisms in an infected duck, but the galliforme species included changes in the polymerase (PB2 A199T, PA D347A), matrix (M1 T218A) and neuraminidase genes (T88I). H5N6-2017 environmental contamination was associated with duck shedding.

Detection and characterization of chicken astrovirus associated with hatchery disease in commercial day-old turkeys in southwestern Nigeria.

Infectious diseases are a major obstacle to profitable poultry production in Nigeria due to the mortality and severe economic losses they cause. In particular, they are a potent threat to attainment of the food security goals of government and national self-sufficiency in food production. Thus, there is a need for continuous monitoring of the nation's poultry population for these diseases. As part of an ongoing investigation of enteric viruses associated with poor performance or hatchery diseases in commercial poultry in southwestern Nigeria, intestinal contents from 97 condemned or runted day-old commercial turkey poults were examined for turkey astroviruses, infectious bronchitis virus, chicken astrovirus (CAstV), avian nephritis virus, avian rotavirus, avian reovirus, fowl adenovirus, and chicken parvovirus by virus isolation, electron microscopy (EM), polymerase chain reaction (PCR), and reverse transcription PCR. The samples were collected from five commercial hatcheries and five farms located in southwestern Nigeria. While all samples tested negative for other viruses, CAstV was detected in the majority (83.5%) of the birds, although some pleomorphic virus-like particles with surface projections that appeared fringed or fimbriated were observed in five of the cell culture samples by EM. Phylogenetic analysis revealed these CAstV strains belonged to the Bi clade. These findings not only implicate CAstV as the major cause of hatchery condemnations in commercial turkeys in southwestern Nigeria but also highlight the need for experimental studies to further establish its role in this disease condition.