Avian diseases最新文献

Vaccination with a recombinant Newcastle disease virus (NDV) LaSota (LS) strain expressing Arkansas (Ark) -type infectious bronchitis virus (IBV) spike ectodomain (Se) protein and granulocyte-macrophage colony-stimulating factor (GMCSF) (rLS/ArkSe.GMCSF, where rLS stands for recombinant LS) was evaluated in chickens of commercial origin with NDV and IBV maternally derived antibodies (MDAs). Chickens were vaccinated ocularly with rLS/ArkSe.GMCSF at either 2, 8, 15, or 30 days of age (DOA). Control chickens were vaccinated with the rLS virus (not expressing IBV SE or GMCSF) on the same days. Specific-pathogen-free (SPF) chickens also were vaccinated with either virus at 2 days old. The results showed detection of NDV RNA in lacrimal fluids of vaccinated chickens, indicating successful replication of the recombinant virus at periocular mucosal sites. IBV IgA in lacrimal fluids and serum IBV antibodies were determined by ELISA using recombinant IBV Ark S1-protein-coated plates. Vaccination at 2 DOA with rLS/ArkSe.GMCSF in chickens with MDAs elicited an IBV IgA response in lacrimal fluids. Chickens with MDAs vaccinated with rLS/ArkSe.GMCSF at 8 days old showed IgA levels in lacrimal fluids not differing significantly from levels achieved upon vaccination at 2 DOA. Vaccination at 30 days old did not result in increased IBV IgA levels in tear fluids of birds with MDAs compared to unvaccinated birds with MDAs. Vaccination with rLS/ArkSe.GMCSF of chickens with MDAs resulted in limited IBV and NDV serum antibody responses. We conclude that vaccination with rLS/ArkSe.GMCSF induces IBV IgA at periocular mucosae but limited serum antibody responses in chickens with NDV MDAs.

We examined the replication and adaptation of avian paramyxoviruses serotype 1 (APMV-1) using four isolates, Mallard/US(OH)/04-411/2004, Northern pintail/US(OH)/87-486/1987, Mottled duck/US(TX)/TX01-130/2001, and Mallard/US(MN)/MN00-39/2000, and assessed their potential as vaccine candidates for chickens. The adaptability of each virus was examined by serial passages in embryonated chicken eggs (ECE) and in Vero cells. All APMVs successfully replicated in ECE. In contrast, two isolates passaged in Vero cells showed successful replication and two showed a continuous decline in viral load during passages. Whole-genome sequencing analysis identified 14 genomic positions with significant variation in mean allele frequency. Changes of the predominant virus population were characterized by shifts of amino acid (aa) frequency at eight positions. Notably, four of these changes were located in the hemagglutinin-neuraminidase (HN) protein, one in matrix (M) protein, and two in the L-protein sequences. Remarkably, although the percentage of alternative amino acids in viral populations passaged in ECE showed limited variation-for example, at aa position 127 of HN, the frequency varied from 7.4% to 19.8% and at HN aa position 192 it varied from 5.1% to 43.5%-the variation of the viral populations passaged in Vero cells was significantly higher at the same positions (e.g., the frequency of the alternative amino acids at HN aa positions 127 and 192 changed from 20.8% to 95.2% and 7.2% to 91.2%, respectively). Isolate 2 passaged in Vero cells displayed a marked variation in alternative aa frequencies, specifically at positions 127 within the HN and 100 within the M proteins. Isolate 3, while showing no alterations at the same HN positions, showed a considerable change in alternative aa frequency in the L protein at position 1875, a change occurring only in the Vero cell environment. One-day-old specific-pathogen-free chickens inoculated with isolates passaged in ECE elicited serum antibody responses similar to those elicited by the LaSota reference strain. In contrast, APMVs passaged in Vero cells showed limited replication in chickens and reduced induction of systemic antibodies. Interestingly, one virus passaged in ECE and another in Vero cells elicited immunoglobulin A levels in lacrimal fluid comparable to the LaSota strain. We concluded that the four wild-bird APMV isolates tested demonstrated successful adaptation to ECE, with one isolate eliciting overall immune responses comparable to the LaSota virus, supporting their potential as vaccine candidates.

From 2015 to 2024, inclusion body hepatitis (IBH) was diagnosed in a total of 346 chicken necropsy cases submitted to the California Animal Health and Food Safety (CAHFS) laboratory system. The majority of cases (68%; 237/346) originated from a single commercial broiler company with a high density of poultry premises within the California Central Valley region. Reported mortality varied between 0.5% and 4.8% per day, and morbidity ranged between 5% and 10%. Clinical signs observed in affected flocks included depression, reluctance to move, ruffled feathers, greenish diarrhea, and, occasionally, icterus of skin and adipose tissue. Typical histopathological lesions included extensive hepatic necrosis, multifocal pancreatic necrosis, gizzard erosions, and glomerulonephropathy. Intranuclear inclusions were identified, mainly within degenerating hepatocytes, followed by pancreatic acinar cells, glandular epithelium of proventriculus and gizzard, and enterocytes of the small intestines and renal endothelium. Diagnosis was based on microscopic changes characteristic of IBH and a positive conventional PCR targeting the hexon gene of fowl adenovirus (FAdV) on liver tissue pools. Sequence analysis was performed on 41 selected FAdV-positive samples from diagnostic cases. The majority of FAdV PCR-positive samples aligned with FAdV-8b (16/41). However, FAdV-7 (14/41), FAdV-4 (7/41), and FAdV-11 (4/41) were also detected from IBH cases. Disease management was successfully achieved by the administration of an autogenous vaccine to breeders, at 11 and 18 wk of age, to confer maternal antibody protection to the broiler progeny.

A breeder flock of 3200 Pekin ducks (Anas platyrhynchos domesticus) experienced a pox virus infection, which affected 40% to 45% of the flock and lasted for a period of 6 wk. No biting insects or equipment that could have caused injury were found, although injury was considered to be the inciting factor. Feed and water consumption as well as egg production and hatchability were unaffected. Pox lesions occurred primarily on the bill, with some ducks having lesions on the eyelid. Infection was confirmed by gross and microscopic examination of affected hens as well as PCR and DNA sequencing. Genetic analysis revealed that the isolate causing the infection was related to pox viral infections in other wild waterfowl found in the United States. This is the first documented case of a naturally occurring pox virus infection in commercial Pekin ducks in the United States.

White chick syndrome (WCS), a vertically transmitted disease caused by chicken astrovirus (CAstV), causes decreased hatchability of broiler breeder progeny and increased hatch of weak, white chicks. In the absence of a commercial vaccine, control measures for WCS have included serological surveillance of pullets, then movement of litter from farms with confirmed CAstV seroconversion to farms with seronegative birds. However, litter movement carries the risk of introducing other pathogens to farms, such as Salmonella. CAstVs have been isolated from clinical cases of WCS and genetically characterized as chicken astrovirus, group Biv based on sequencing of the capsid protein. Autogenous vaccines (AVs) have included CAstVs, but no data exist to validate their ability to stimulate adequate immunity in breeders to prevent WCS. The objectives of this study were to 1) develop a CAstV Biv-inactivated oil emulsion vaccine using a CAstV isolate from a clinical case of WCS and 2) evaluate antibody production following injection into 3-wk-old specific-pathogen-free (SPF) leghorns. The CAstV isolate was propagated and titrated in leghorn male hepatoma cells, inactivated using beta-propriolactone, formulated into an oil emulsion with Montanide® ISA 70 VG adjuvant and then injected intramuscularly into 3-wk-old SPF leghorns. Birds received a second injection at approximately 9 wk of age. A negative control group received no vaccination at either time point. Serum was collected at 0, 2, 4, 8, 10, 12, and 14 wk post-initial vaccination (wpiv) for CAstV ELISA (BioChek®) and CAstV virus neutralization assay (VN). At 0, 2, and 4 wpiv no vaccinated birds had measurable antibody levels via enzyme-linked immunosorbent assay (ELISA) and VN tests. At 8, 10, 12, and 14 wpiv CAstV-specific antibodies were not detected by ELISA in either group; however, seroconversion was observed by VN in CAstV-vaccinated birds. Serum samples collected from breeder flocks with progeny that were clinically affected with WCS had consistently high ELISA titers, but the VN titers, while positive, were more variable. Control of WCS with a CAstV AV may be an option for use in broiler breeders. Progeny studies to detect maternal antibody transfer after vaccination would be useful in confirming this assertion. Based on this study, VN serology using a genetically similar CAstV as antigen is the preferred method of monitoring vaccinated flocks for seroconversion given the lack of antibody detection by ELISA. The ability to determine efficacy of any vaccine would rely solely on field observations as there is no established challenge model for WCS.

The global outbreak of clade 2.3.4.4b H5 highly pathogenic avian influenza (HPAI) has caused tremendous losses in poultry worldwide. Although turkeys are a smaller sector in poultry production compared to chickens, they tend to be affected more severely by HPAI because they can usually be infected with a lower dose of virus (i.e., they are more susceptible). Vaccines can be effective tools to help control HPAI, but data on vaccine efficacy and antibody response in turkeys are somewhat limited. Here we evaluated an in-house-produced, reverse-genetics-generated H5N9 inactivated vaccine that has a clade 2.3.4.4b H5 HA from A/turkey/Indiana/22-003707-003/2022 (TK/IN/22) modified to be low pathogenic and a North American wild bird lineage N9 in a PR8 "backbone" for its efficacy in commercial broad-breasted white turkeys by homologous challenge. Turkeys were divided into three vaccination groups, where each group was vaccinated once at 3, 7, or 9 wk of age. Turkeys were challenged at 10 wk of age with TK/IN/22 HPAI virus. There was 100% survival in all vaccinated groups and 0% survival in the sham immunized group. A significant decrease in viral shedding was observed in all vaccinated groups compared to the sham immunized turkeys. Also, the 9 wk vaccination group shed significantly higher quantities by the cloacal route at 7 days postchallenge (DPC) compared to the 3 wk vaccination group, and two turkeys in the 9 wk vaccination group had mild clinical signs 6-7 DPC. The neuraminidase inhibition-enzyme-linked lectin assay (NI-ELLA) was used to evaluate antibodies to the vaccine and was more sensitive than the hemagglutinin inhibition assay. Also, when tested as a potential assay to differentiate vaccinated and infected animals, 50% to 90% of vaccinated turkeys (depending on the age at vaccination) were positive by NI-ELLA at 7 DPC for antibodies to the challenge virus, and 100% were positive at 14 DPC.

Escherichia coli is a ubiquitous organism that colonizes a variety of animal hosts and has the ability to persist within the environment. As such, it is not surprising that animals frequently share E. coli strains and contribute to environmental E. coli ecology. It has been well documented that poultry meat can serve as a reservoir of avian pathogenic E. coli (APEC) with the potential to cause human disease. However, the impact of backyard poultry rearing on household and community APEC sharing is less clear. In this study, we examined 1348 E. coli isolates from children, dogs, and chickens in 222 households in peri-urban communities of Quito, Ecuador, sampled across five timepoints. Extensive overlap between isolates from all three host sources were identified using Clermont phylotyping and multilocus sequence typing. Human and dog isolates also had a high rate of carriage (37% and 49%, respectively) of genes indicative of APEC. Phylogenetic analyses of dominant sequence types (ST10, ST155, ST117, ST2847, ST162, ST38, and ST354) provided examples of highly related clones found between host sources and households, and spanning timepoints. Overall, this study illustrates the apparent extensive sharing of E. coli that occurs across peri-urban communities. The high rates of carriage of APEC by humans and dogs in this study contrasts with previous work examining the carriage of APEC in mammalian hosts and suggests that widespread rearing of, and frequent contact with, backyard chickens may influence the dissemination of APEC within households and communities.

The unavailability of drugs and vaccines has resulted in a resurgence of histomoniasis outbreaks in recent years. Studies have been conducted to understand the infectivity of Histomonas meleagridis field isolates and develop early diagnostic tools for histomoniasis. To better understand the underlying physiological impact of H. meleagridis, serum clinical chemistry analytes were evaluated in three independent studies. Poults were challenged with wild-type H. meleagridis isolates by the cloacal route. In studies 1 and 2, blood samples were collected 9 days postchallenge (PC), while in study 3, blood samples were collected at 5 and 8 days PC for serum analysis. Among the several serum parameters evaluated, serum cholesterol and ALKP were consistently and significantly depleted in poults challenged with wild-type H. meleagridis. Depletion of serum cholesterol and ALKP was documented as early as 5 days PC with H. meleagridis.

To assess the efficacy of two inactivated vaccines against Avibacterium paragallinarum serovar B variant infection in laying hens, day-old female chicks were allocated into five experimental groups (G): G1 received a commercial vaccine V1, strains 17756, 0222, and Modesto of serotypes A, B, and C, respectively, at 8 and 12 wk of life; G2 received V1 through an early vaccination plan at 5 and 12 wk of life; G3 received another commercial vaccine V2, strains 083, Spross, 48, and H18 of serotypes A, B, Bvar, and C, respectively, against infectious coryza, which contained a serovar B variant strain in its formulation at 8 and 12 wk of life. Chickens in G4 were not vaccinated and challenged and were used as positive control, and G5 was not vaccinated and not challenged and served as negative control. At 25 wk of life, chickens from G1 to G4 were inoculated (by injection into the infraorbital sinus) with the serovar B variant of Av. paragallinarum, strain INTA H8, into the left infraorbital sinus of each animal. Clinical signs were monitored daily until Day 5 postchallenge. On that day, bacterial isolation was performed on both inoculated and noninoculated sinuses from each animal to determine the presence of Av. paragallinarum. The interpretation of clinical signs involved grading on a scale from 0 to 4, depending on the severity of conjunctivitis and swelling of the periorbital area. On Day 2 postchallenge, the highest number of birds from all inoculated groups exhibiting clinical signs was recorded, gradually decreasing over the following days. The unvaccinated group (G4) had significantly (χ², P < 0.05) more birds with clinical signs compared to vaccinated birds, regardless of the immunization plan or age. Overall, no significant differences were observed between G1 and G3 on any of the postchallenge observation days. However, G1 had significantly fewer birds exhibiting clinical signs compared to G2, the group that received the early vaccination plan. On the other hand, comparing the results of the noninoculated sinuses, no differences were found among vaccinated birds in G1, G2, and G3, whereas significantly more infected sinuses were found in the nonvaccinated birds. In conclusion, both V1 and V2 demonstrated efficacy in significantly reducing clinical signs, both with the conventional vaccination plan at 8 and 12 wk of life (V1 and V2) as well as with early vaccination starting at 5 wk of age (V1), compared to nonvaccinated birds. It also showed effectiveness in reducing the presence of Av. paragallinarum in the infraorbital sinuses following the experimental challenge with the serovar B variant. Furthermore, V1, which does not have a Bvar strain, was proven to be effective against the serovar B variant of Av. paragallinarum, specifically demonstrating its efficacy in protecting against clinical signs associated with this particular serovar.

Increased fat content and inflammation are observed in woody breast (WB) muscles, suggesting dysregulation of fatty acids and inflammation in WB conditions. This study evaluated the gene expression related to fatty acid metabolism and inflammation responses in WB muscle. In total, 112 Ross × Ross 708 broiler chickens were raised following the commercial husbandry recommendations in a floor-pen chicken house. On day 41, the WB condition of each bird was assessed through palpation, and the birds were then categorized into normal and WB phenotypes. Next, 10 birds were euthanatized, five of which exhibited normal breast conditions (normal group) and five of which exhibited WB conditions (woody group), and breast muscle was sampled. RNA was extracted and reverse transcribed. The first-strand complementary DNA (cDNA) was analyzed using the real-time RT² Profiler PCR Array, targeting 84 genes associated with chicken fatty acid metabolism and five housekeeping genes. Additionally, this cDNA was subjected to real-time quantitative PCR for 10 inflammatory genes, utilizing the chicken 18S rRNA gene as housekeeping control. Fold changes were calculated using the difference in cycle threshold (ΔΔCt) method and were compared using the Student t-test with a significance level set at P ≤ 0.05. Eight of the 84 examined genes related to lipid metabolism showed differential expression (P ≤ 0.05) between normal breast and WB samples. Specifically, three genes were upregulated (P ≤ 0.05) in WB samples: acetyl-coenzyme A acetyltransferase 2, alcohol dehydrogenase 6, and glycerol kinase. In contrast, five genes were downregulated (P ≤ 0.05) in WB samples: acyl-coenzyme A (CoA) dehydrogenase, acyl-CoA synthetase medium-chain family member 4, glycerol-3-phosphate dehydrogenase 2, 5'-AMP-activated protein kinase subunit beta-2, and 5'-AMP-activated protein kinase subunit gamma-3, where AMP is adenosine monophosphate. Compared to the normal group, the expression levels of Toll-like receptor 2A, Toll-like receptor 4, interferon-γ, interleukin-1β, and interleukin-6 in the WB group were significantly increased (P ≤ 0.05). In conclusion, gene expression in WB muscle indicated upregulation of lipid biosynthesis, downregulation of fatty acid catabolism, and an activated inflammation response. This study revealed significant gene expression changes in fatty acid metabolism and inflammatory responses as key factors in the development of WB in broilers.