Avian Pathology最新文献

The Duck Tembusu virus (DTMUV) was first reported in China in 2010 and has since caused substantial economic losses in the poultry breeding industry. In the autumn of 2022, an outbreak of an infectious disease resembling DTMUV was reported in Guangdong Province, China, which caused significantly high mortality in goose embryos, and decreased egg production. This study identified one strain of the new subgenotype 3 of DTMUV, designated as DTMUV GDZQ2022, responsible for these effects. Comprehensive genomic sequencing of this strain was conducted to analyse its genetic variations. Additionally, the isolated and purified virus was inoculated into goose embryos and goslings to assess its pathogenicity. The GDZQ2022 genome displayed over 88% nucleotide homology with other DTMUV strains from China and Southeast Asia. Phylogenetic analysis of the E gene classified GDZQ2022 within the subgenotype 3 of DTMUV. Pathogenicity experiments on goose embryos and goslings showed that the GDZQ2022 strain induced typical clinical signs of DTMUV, particularly severe neurological manifestations. Although GDZQ2022 exhibited high virulence in goose embryos, its virulence in goslings was minimal, resulting in a low mortality rate. Pathological examinations detected significant histological lesions in the brains, livers, and spleens of the infected goslings. In conclusion, this study presents the first evidence of a novel DTMUV strain proliferating among young geese in China, underscoring the genetic diversity of DTMUV and contributing to our understanding of the pathogenicity of the subgenotype 3 Tembusu virus in goose embryos and goslings.RESEARCH HIGHLIGHTSPathogenicity of subgenotype 3 duck Tembusu virus in goose embryos and goslings was shown for the first time.DTMUV GDZQ2022 strain is highly pathogenic in goose embryos.The virulence of the DTMUV GDZQ2022 strain in goslings is relatively mild.Infected goslings exhibit typical clinical manifestations, with a low mortality rate.

We characterized 15 H5N1 HPAI viruses from different small- and medium-scale poultry flocks across Bangladesh during 2018-2021 based on their complete genome sequences. The antigenic relatedness of H5N1 HPAI viruses from different timepoints was analysed. During 2020-2021, 42.11% of the flocks tested positive for at least one of the respiratory infections, with 15.79% showing influenza A virus, of which 8.77% tested positive for HPAIV H5N1. Co-infections with two to four pathogens were detected in 15.8% of flocks. Phylogeny and gene constellation analyses based on complete genome sequences of 15 HPAI viruses revealed the continuing circulation of H5 clade 2.3.2.1a genotype G2 viruses. In the HA protein of the study isolates, functionally meaningful mutations caused the loss of an N-linked glycosylation site (T156A), a modified antigenic site A (S141P), and a mutation in the receptor binding pocket (E193R/K). Consequently, antigenic analysis revealed a significant loss of cross-reactivity between viruses from different host species and periods. Most viruses displayed oseltamivir resistance markers at positions V96, I97, S227, and N275 (N1 numbering) of the NA protein. In addition, for the PB2, M1, and NS1 proteins, significant mutations were noticed that have been associated with polymerase activity and increased virulence for mammals in all study isolates. These results highlight the need for intensified genomic surveillance of HPAI circulating in poultry in Bangladesh and for establishing appropriate control measures to decrease the circulation of these viruses in poultry in the country.

Mycoplasma gallisepticum (Mg) and Mycoplasma synoviae (Ms) are regarded as the most important avian mycoplasma species for today's chicken and turkey farming industry from clinical and economical perspectives. Control strategies for Mg and Ms have become more efficient due to investments in mycoplasma research over the last 70 years. These investments have contributed to the further implementation of serological and molecular testing, the development of vaccines, and the improvement of antimicrobial treatment strategies. However, the increasing spotlight on welfare, the pressure on prudent use of antimicrobials, and the expected global increase in poultry production, are going to have an impact on the future control of avian mycoplasmas in commercial poultry. In this paper a group of avian mycoplasma experts discuss the future challenges in mycoplasma control considering the background of these expected changes and the relevance for future avian mycoplasma research.

Two vaccination-challenge trials were performed using a commercial infectious bronchitis virus (IBV) BR1 vaccine, given alone or combined with a commercial IBV Mass vaccine against challenges with IBV M41, 793B, D388 (QX), Q1, Brasil-1 or Variant 2 challenge viruses, which includes the IB viruses that are dominant in South America. The efficacy of the vaccines against the challenge viruses was investigated by determination of the ciliary activity of the tracheal epithelium after challenge. The level of protection induced by the IBV BR1 vaccine alone against the six IBV challenge strains, of which five were of heterologous genotypes, varied from 50% to 100% with an average of 80%. The level of protection induced by the combination of the IBV BR1 and IBV Mass vaccines against the six IBV challenge strains, of which four were of heterologous genotypes, varied from 80% to 100% with an average of 92%. Vaccination with IBV BR1 alone provided a high level of protection against most tested challenge viruses, though the combination of IBV BR1 and IBV Mass was more consistent, showing less variation and compliance with the criterium mentioned in the European Pharmacopoeia 10th edition (at least 80% protection) for all tested challenge viruses. These trials show that vaccination with a combination of IBV BR1 and IBV Mass vaccines provides high levels of protection against the circulating IBV strains in South America.

Inclusion body hepatitis (IBH) is an economically important viral disease primarily affecting the poultry industry. In this study, we isolated a strain of FAdV-8b (strain SDYT) from naturally infected ducks and the hexon and fiber gene sequences were analysed by polymerase chain reaction (PCR) amplification. In order to study the pathogenicity of FAdV-8b in Cherry Valley ducks, we inoculated 10- and 20-day-old ducks with 0.3 ml of FAdV-4 virus (TCID₅₀ of 10^5.5/0.1 ml) either orally or intramuscularly. Clinical signs, gross lesions and histopathological changes, cytokines, viral load and antibody levels were observed and recorded within 15 days after infection. Pathomorphological investigations revealed that ducks in the experimental group exhibited hepatitis. Histopathology showed multiple organ damage, including serious liver and kidney lesions. Furthermore, elevated levels of inflammatory cytokines and antibodies were noticed, due to the infection and innate immune response. At a later stage of infection, immunosuppression occurred, resulting in decreased levels of cytokines. Determination of viral load showed that the virus was present in several organs, with the highest viral DNA load found in the liver, followed by the kidney. Compared to birds infected orally, the intramuscular group exhibited the highest viral load. In summary, this study increases our understanding of the pathogenicity of FAdV-8b in ducks and establishes a model that will inform antiviral drug testing and vaccine evaluation for IBH, thereby preventing and reducing the spread of IBH in the poultry industry.RESEARCH HIGHLIGHTSA strain (SDYT) of fowl adenovirus 8b (FAdV-8b) was successfully isolated from ducks.Cherry Valley ducks were successfully infected with FAdV-8b.Different routes of infection can lead to duck mortality, more pronounced when birds are injected intramuscularly.FAdV-8b (SDYT) was distributed in various tissues and organs of ducks, causing different degrees of lesions.

The use of copper nanoparticles (CuNP) in the diet of broiler chickens has been studied as a potential alternative to antibiotic growth promoters. This study aimed to analyse the antimicrobial properties of CuNP in the feed and water of broiler chickens against Salmonella Enteritidis and to assess the intestinal integrity and toxicity of CuNP supplementation in their diet. The antimicrobial activity of CuNP against S. Enteritidis was tested in microplates to evaluate three water samples with different mineral compositions and in an in vitro digestibility model that simulated the three primary intestinal compartments of birds to assess feed samples. To evaluate in vivo intestinal integrity and toxicity, the birds were divided into four groups (30 birds per group): (1) basal diet (control); (2) basal diet + CuNP (100 ppm); (3) basal diet + enramycin (10 ppm); and (4) basal diet + CuNP (100 ppm) + enramycin (10 ppm). Intestinal samples were collected for histomorphometric evaluation and lactic acid bacteria count, while chest muscle and whole blood samples were collected to determine copper content. A significant reduction in the S. Enteritidis count was observed in both in vitro treatments (water and feed) with CuNP inclusion, compared to the control group. No significant differences in histomorphometric measurements, weight gain, or total lactic acid bacterial counts were found compared to those in the control. These results demonstrate the effectiveness of CuNP in reducing the occurrence of S. Enteritidis and their non-interference with the intestinal integrity of broiler chickens, highlighting the potential of CuNP as an alternative antimicrobial agent in the poultry production chain.RESEARCH HIGHLIGHTSSupplementation with CuNP in feed and water reduced Salmonella Enteritidis count.Supplementation with CuNP did not affect intestinal integrity of broilers.CuNP did not affect weight gain or total lactic acid bacterial counts.The results demonstrate the potential of CuNP as alternative antimicrobials.

Nontyphoidal serovars of Salmonella enterica subsp enterica frequently colonize the intestinal tracts of chickens, creating risks of contamination of meat and egg food products. These serovars seldom cause disease in chickens over 3 weeks of age. Colonization is generally transient but can continue to circulate in a flock for many months. Vaccination of breeders and layers is the most effective method of control of infections with serovars Enteritidis and Typhimurium, and the development of these vaccines or other preventative treatments requires challenge studies to demonstrate efficacy. However, establishing a successful challenge model where the control birds are colonized to a sufficient extent to be able to demonstrate a statistically significant reduction from the vaccine or treatment is problematic. A meta-analysis of published S. Enteritidis challenge studies was performed to pursue the best challenge model conditions that provide consistent control colonization outcomes. Challenge at sexual maturity was significantly more effective in achieving at least 80% colonization of control hens.RESEARCH HIGHLIGHTSSalmonella challenge chicken models do not always achieve high colonization levels in controls.The age of hen is important in achieving good caecal colonization.Challenge around sexual maturity provides the best control colonization outcome.A challenge dose rate of 10⁵ CFU/ bird is adequate in birds under 30 weeks of age.

Avian leukosis virus subgroup J (ALV-J) is an alpharetrovirus that infects chickens, causing immunosuppression and a decrease in production performance, leading to substantial economic losses in the poultry industry. ALV-J is also well-known for its oncogenic properties, inducing tumours such as myelomas and haemangiomas in infected chickens. TRIM45 has been identified as a potential tumour suppressor; however, the relationship between TRIM45 expression and ALV-J infection remains to be elucidated. This study aimed to dissect the molecular characteristics of the chicken TRIM45 gene and its modulation during ALV-J infection, as well as its influence on viral replication. We found that the chicken TRIM45 RING domain is significantly different from that of humans and other mammals. TRIM45 is expressed in all chicken tissues, with the highest levels in the heart. Subcellular localization studies indicated a cytoplasmic distribution of TRIM45, forming aggregates within cells. Our findings demonstrate that ALV-J infection significantly upregulates TRIM45 expression in DF-1 cells. To assess the functional role of TRIM45 in ALV-J replication, we employed both gene silencing and overexpression strategies. Strikingly, the overexpression of TRIM45, including a mutant lacking the RING domain, was found to markedly suppress ALV-J replication. In contrast, TRIM45 knockdown via siRNA resulted in an enhanced viral replication, highlighting the importance of TRIM45 limiting ALV-J replication. Mechanistically, overexpression of TRIM45 induces apoptosis in infected cells, independent of its RING domain function. In conclusion, our study demonstrates that chicken TRIM45 acts as a negative regulator of ALV-J replication in vitro by promoting apoptosis in infected cells.RESEARCH HIGHLIGHTSChicken TRIM45 RING domain and protein localization significantly differ from humans.TRIM45 negatively regulates ALV-J replication in vitro.TRIM45 inhibits ALV-J replication by inducing apoptosis in infected cells.

In this study, we investigated the pathological effects of novel goose parvovirus (NGPV) infection on the skeletal muscle, brain, and intestine of naturally affected ducks suffering from locomotor dysfunction as a new approach for a deeper understanding of this clinical form. For this purpose, a total of 97 diseased ducks, representing 24 flocks of different duck breeds (14-75 days old), were clinically examined. In total, 72 tissue pools of intestine, brain, and skeletal muscle samples were submitted for molecular identification. Typical clinical signs among the examined ducks suggested parvovirus infection. Regarding postmortem examination, all examined ducks showed muscle emaciation (100%) either accompanied by congestion (34%) or paleness (66%). Slight congestion, either in the brain (82.5%) or intestine (75.25%), was predominantly detected. Based on molecular identification, the intestine had the highest percentage of positive detection (91.7%), followed by the skeletal muscle (70.8%), and the brain (20.8%). The main histopathological alterations were myofibre atrophy and degeneration, marked enteritis accompanied by lymphocytic infiltration in the lamina propria and submucosa, while the affected brains showed vasculitis, diffuse gliosis, and Purkinje cell degeneration in the cerebellum. Next-generation sequencing further confirmed the presence of a variant strain of goose parvovirus (vGPV) that is globally known as NGPV and closely related to Chinese NGPV isolates. Using immunohistochemistry, the NGPV antigen was positively detected in the muscle fibres, enterocytes, and Purkinje cells in the cerebellum. These findings provided proof of the involvement of virus replication in the locomotor disorders linked to NGPV infection in ducks.