Avian diseases最新文献

Fowl aviadenoviruses (FAdVs) are widely distributed among poultry populations, leading to various diseases, immunosuppression, and economic losses. Molecular characterization and phylogenetic analysis of circulating FAdV isolates play a critical role in epidemiologic studies, contributing to the control, monitoring, and prevention of related outbreaks. This study aimed to determine the serotypes of FAdV and reveal the molecular epidemiology in broiler chicken flocks. Samples were taken based on epidemiologically important parameters, such as vaccination status, age, and transmission route. A total of 20 vaccinated flocks (VF, flocks originated from vaccinated breeder lines) and 20 nonvaccinated flocks (NVF, flocks originated from nonvaccinated breeder lines) were randomly selected from flocks reporting suspected FAdV clinical symptoms and deaths. Vaccination was administered by intramuscular injection into the pectoral muscle with a commercial inactivated vaccine at 12 and 18 wk. Liver and cloacal swab samples were collected from each flock over two different production cycles and for three different age groups (1-day-old, 14-day-old, and 28-day-old chickens). The liver and cloacal swap samples were analyzed for FAdV using PCR targeting the hexon loop-1 gene. Molecular detection revealed that 30.0% (24/80) of all flocks were FAdV positive, with 50.0% (20/40) positivity in NVF and 10.0% (4/40) in VF. Sequence analysis of the hexon loop-1 gene revealed that all samples were FAdV-8b serotype (OR670689-OR670712), with 100.0% similarity. One randomly selected FAdV-8b sample was analyzed by whole-genome sequence analysis. This is the first study in Turkey to deposit an FAdV whole-genome sequence (44,139 bp) into the GenBank database (PP236873). Given the significantly lower FAdV positivity rates in VF compared to NVF, the findings indicate that vaccination is an effective tool for protecting against FAdV-related infections.

Cochlosoma anatis is a flagellated protozoan parasite classified in the Trichomonadidae family and is the causative agent of cochlosomiasis, an enteric disease of turkeys, waterfowl, and other wild birds. Cochlosomiasis symptoms largely consist of watery diarrhea, lethargic birds, depressed weight gain, and widespread flock morbidity causing flock nonuniformity. The known distribution of C. anatis is centered around areas of turkey production farms in the southeast United States, e.g., North Carolina, Missouri and Arkansas, but has been reported in other states and some other countries. Diagnosis is confirmed through examination of enteric mucosal scrapings using light microscopy. Following the withdrawal of approval of effective antiprotozoal medications for use in commercial animal production, cochlosomiasis has become a greater concern for commercial turkey industry professionals. Transmission of C. anatis occurs via the fecal-oral route, but the organism is fragile outside the host, suggesting the implication of a vector in the introduction of disease to susceptible farms. Research regarding C. anatis pathogenicity, transmission, and environmental involvement has been limited, creating a gap in cochlosomiasis knowledge. Future research is needed to further explore ways to prevent and treat cochlosomiasis, with needs centered on disease pathogenesis, transmission patterns, and prophylaxis and treatment methods.

Immune responses in the Harderian gland (HG) were characterized after Newcastle disease virus (NDV) LaSota ocular vaccination in antibody-naïve specific-pathogen-free (SPF) chickens and in chickens of commercial origin with NDV maternally derived antibodies (MDA). Ocular LaSota vaccination of 13-day-old white leghorn SPF chickens elicited serum antibody levels that consistently increased 15 days postvaccination, while the specific IgA response in lacrimal fluids was already detectable 10 days after vaccination. Eleven days postvaccination, the relative abundance of B cells, as well as T-helper cells (CD4⁺) and cytotoxic T cells (CD8⁺), in HGs was significantly increased, achieving maximum frequencies 16 days postvaccination. In a second experiment, chickens with MDA originating from NDV-vaccinated commercial white leghorn layer breeders, as well as white leghorn SPF chickens, were vaccinated with NDV LaSota. The LaSota virus successfully replicated in periocular tissues and in the trachea both in commercial and control SPF chickens after vaccination at 2 or 15 days of age (DOA). Vaccination at 2 DOA did not induce a serum NDV antibody response in chickens of commercial origin. In contrast, seroconversion was elicited in commercial chickens upon vaccination at 15 DOA, likely associated with waning of MDA. Unlike systemic IgG responses, vaccination at 2 or 15 DOA elicited strong specific IgA responses in lacrimal fluids in commercial chickens. The IgA response was highest 9 days after vaccination and showed a tendency to decline 15 days postvaccination. Commercial chickens vaccinated at 2 DOA showed increased B cells in HG 10 and 16 days postvaccination. The expansion of B cells in the HG in these chickens is consistent with increased IgA levels detected in lacrimal fluids. In contrast, control SPF chickens showed a more limited B-cell expansion in HG and lower IgA levels. Vaccination at 15 DOA also triggered a greater increase of B cells in HGs in commercial chickens than in control SPF chickens. The B-cell response was accompanied by T-helper (CD4⁺) cell expansion, occurring both in commercial and control SPF chickens. These cells expanded to a lesser extent when vaccination was performed at 2 DOA compared with vaccination at 15 DOA. CD8⁺ showed significant expansion irrespective of vaccination day and without differences detected between control SPF chickens and chickens with MDA. We conclude that NDV LaSota elicits vigorous humoral and cell immune responses in the HG. Furthermore, unlike the interference shown by MDA on vaccine-induced serum antibody responses, MDA do not interfere with the mucosal immune response of the HG.

Fowl cholera, caused by Pasteurella multocida infection, poses challenges for prevention because of its many serotypes. Bacterins are currently widely used for vaccination against fowl cholera, but protection is limited to homologous strains. Live attenuated vaccines of P. multocida provide some heterologous protection, but side effects are considerable. More recently, protein-based antigens are promising subunit vaccines when their low immunogenicity has been addressed with effective adjuvants. Bacterial flagellin has been widely considered a promising adjuvant for vaccines. In this study, we tested the adjutancy of flagellin in a subunit vaccine against P. multocida in a mice and chicken models. For vaccine formulation, the antigen fPlpE (P. multocida liporotein E) was combined with fFliC (Salmonella Typhimurium flagellin). The recombinant proteins of fPlpE and fFliC were successfully expressed using the Escherichia coli system as the expected sizes of 55 kDa and 70 kDa, respectively. The fFliC elicited strong expression levels of proinflammatory cytokine (IL-1β, IL-8, and IL-6) when stimulated in native chicken peripheral blood mononuclear cells. Immunization of mice and chickens with the subunit vaccines containing fFliC accelerated the antibody response. In the challenge tests, fFliC increased vaccine protective efficacy against the heterologous strain P. multocida A1 and highly virulent strain Chu01 in mice and chickens, respectively. These data indicated potential possibilities of using fFliC as an immunostimulant adjuvant in developing a subunit vaccine against fowl cholera.

Clostridium perfringens (CP)-induced necrotic enteritis (NE) is an economically important disease in the broiler chicken industry. The incidence of NE is common in 3-to-6-wk-old broiler chickens, once maternal antibodies start declining. Developing an effective vaccination strategy against NE, preferably delivering a single dose of vaccine at hatch to protect broiler chickens against NE without a booster vaccine, is an enormous challenge. The objective of this study was to induce mucosal immunity in the intestines against NE by intrapulmonary (IPL) delivery of a live CP vaccine at hatch, exploiting the gut-lung-axis (GLA) concept by vaccine delivery following in ovo administration of cytosine-phosphorothioate-guanine oligodeoxynucleotides (CpG-ODN) to induce immune cell maturation in the lungs. Experiments were conducted to explore the dose of CP and immune protection against heterologous CP challenge, and to study the efficacy of IPL delivery of a CP vaccine without a booster. Additional studies were conducted to measure serum immunoglobulin (Ig)Y, mucosal IgA, and histopathology of lungs following vaccination. Delivery of a live CP vaccine by the IPL route, with or without in ovo CpG-ODN, provided significant protection against NE (P < 0.0001). Systemic IgY and mucosal IgA against CP were correlated with protection against NE. There was no necrosis or inflammation in the pulmonary parenchyma. There was a low number of CP isolated from the lungs following live CP delivery by the IPL route. A significant influx of (P < 0.001) of CD8+ T cells and macrophages were noted in the lungs 2 days following live CP delivery by the IPL route. IPL delivery of a live CP vaccine, rather than inactivated CP, provided better protection. This study demonstrated the utility in exploiting the GLA concept in vaccine delivery in broiler chickens.

Avian nephritis virus (ANV), which belongs to the family Astroviridae, is associated with different clinical manifestations (enteric and kidney disorders) in poultry. Despite being a significant pathogen of the avian industry worldwide, information regarding genetic features of these viruses in India is scarce. In this study, 386 intestinal samples collected from 37 slaughterhouses in two north Indian states (Rajasthan and Haryana) were screened for ANV with reverse transcription PCR (RT-PCR) targeting the conserved ORF1b gene, followed by nucleotide sequencing of the amplified product. RT-PCR and sequencing confirmed the presence of ANV in 32 clinical samples (8.29%), with concurrent infections of infectious bronchitis virus, chicken astrovirus, and fowl adenoviruses observed in some clinical samples (n = 4). Virus isolations were successful from four out of 12 ANV-positive clinical samples passaged via the yolk-sac route in specific-pathogen-free embryonated chicken eggs. Additionally, the near-complete genomes of two viruses were determined through sequencing. Phylogenetic analysis based on full-length capsid protein sequences classified the viruses into ANV genotype 4 (ANV4), and to the best of our knowledge this is the first report of ANV4 from India. This study revealed the presence and circulation of new strains of ANV in Indian poultry. Genetic profiling and isolation of the viruses in this study will not only aid in the development of diagnostic tools and vaccines for ANV but also offer valuable insights into its epidemiology.

Avian influenza virus (AIV) causes frequent outbreaks in poultry with high morbidity and mortality. The virus can survive on different fomites, resulting in indirect transmission to susceptible hosts. We investigated the inactivation by ozonated water (O3W) of three different subtypes of AIV (H4N8, H4N6, and H9N9) on seven different fomites. All subtypes were sensitive on all fomites, but there was a slight variation in the sensitivity of different subtypes. For example, AIV H9N9 showed more than 99% reduction on denim fabric, polypropylene, and Styrofoam after 3 min of exposure. More than 97% of H4N8 was eliminated from cardboard, denim fabric, and stainless steel after 3 min of exposure. Subtype H4N6 was the least sensitive; highest inactivation (98%) was seen on cardboard and polypropylene after 3 min of exposure. In conclusion, O3W can inactivate a large percentage of AIV applied to fomites within 3 min in all tested subtypes. Interestingly, an increase in contact time to 10 min did not result in an increase in the virus inactivation rate, probably because of the low half-life of ozone. Further studies are needed to determine how the residual virus can be inactivated so that it does not pose a problem to naïve birds.

Newcastle disease virus (NDV) is one of the most important pathogens affecting poultry, given its impact on health and production systems worldwide, despite widespread vaccination. Over the past 20 years, NDV has caused severe outbreaks of disease in Peru. These outbreaks primarily affected gamecocks and broiler chickens, with an additional reported case in commercial layers. Therefore, our objective was to identify and characterize the virus responsible for these cases in Peru. We analyzed 14 suspected clinical cases in domestic birds for NDV detection, isolation, and genetic characterization. Among these cases, seven involved gamecocks, with six genotype XII isolates and one genotype VII isolate, representing the first report of NDV genotype VII isolate from fighting roosters in Peru. Additionally, among the six cases in broiler chickens, we detected four genotype XII isolates and three genotype II isolates, including one sample containing both genotypes XII and II. Furthermore, a genotype I viral isolate was identified in a laying hen. Hence, we concluded that two divergent, highly virulent NDV genotypes, genotypes XII and VII, along with avirulent forms such as genotypes I and II are circulating among domestic birds in Peru. Genetic analysis indicates that these viruses are evolving locally within avian species and offers the basis necessary for vaccine adaptation to circulating viruses. Our results highlight the cocirculation of multiple virulent and nonvirulent NDV genotypes in domestic birds in Peru, underscoring the potential role of gamecocks as a viral source of virulent NDV strains in the country and the occurrence of outbreaks in poultry farms.

A four-house broiler breeder farm of approximately 35-wk-old hens was diagnosed with egg drop syndrome (EDS'76) utilizing PCR and hemagglutination inhibition (HI) testing. Based on communication with local practitioners, the geographic area near where this flock was located had numerous EDS'76 cases in table egg layers at the time of diagnosis. An egg production drop was seen in the broiler breeder flock over a 7-day period, which prompted an investigation. During this investigation, a significant number of shell-less, wrinkled, and pale eggs were noted, but no increases in mortality or respiratory signs were observed. The disease and subsequent production drops spread horizontally across the farm over a 5-wk period. Production returned to approximately the breed standard egg production 4 wk after initial egg production drop. However, hatching egg utilization continued to be reduced for another 2 wk because of the number of thin-shelled eggs. A similar pattern of drop in egg production and subsequent return was observed in the other houses. No significant lesions were noted in the tissues submitted for histopathology. Differential diagnoses that could cause shell abnormalities and egg production drops were ruled out by submitting appropriate samples for diagnostic investigation. Egg drop syndrome 76 PCR was performed on shell-less eggs and EDS'76 was detected by PCR at two separate laboratories. Subsequently, serum was submitted for HI and positive results were found in each house as they showed egg production drop concurrent with shell abnormalities. At the time the flocks returned to breed standard production, EDS'76 titers were consistent with a uniformly exposed and seroconverted flock. The authors suspect that immunosuppression as pullets played a role in this flock being impacted by EDS. No other farms in the company's system were observed with production drops or shell abnormalities similar to this case.

A case of increased mortality was investigated at a German farm housing Japanese quails (Coturnix japonica) for egg production. Different age groups were kept in aviaries in one barn. The quail chicks had diarrhea and the adults were emaciated, some also with diarrhea and conjunctivitis. Postmortem examination showed gross tumorlike lesions in 7 of 15 adult quails examined, with ocular lesions in 2 of them. On histopathological examination, infiltrates of monomorphic round cells were found in liver, spleen, lung, and proventriculus. In the eyes of two quails, similar cells were infiltrating the choroid layer, limbus, and adjacent parts of the cornea. Malignant lymphoma was diagnosed. Immunohistochemical examination identified tumor cells as T cells, and Mardivirus gallidalpha 2-specific PCR was positive for five quails with gross lesions. Additionally, Proteus mirabilis and Klebsiella pneumoniae were detected in the chicks and Clostridium spp. and coccidia in the adults. Marek's EcoQ protein (Meq) gene from Mardivirus gallidalpha 2 was sequenced and analyzed, confirming Marek's disease. The results of our examinations demonstrate that the ocular lesions were caused by Marek's disease and that the Meq gene from Mardivirus gallidalpha 2 was detected in the flock of quails. As a control strategy for Marek's disease in quails, an all-in/all-out system was introduced. Additional laying quails acquired from a breeder at 35 days of life were vaccinated at stabling with a combined turkey herpesvirus (HVT)-Rispens vaccine and 14 days later with a Rispens vaccine. Subsequently, the losses and laying rates returned to normal.