查看更多>>摘要：Sanitary disposal of contaminated organic material during recovery from an animal disease outbreak is costly and laborious. Characterizing the thermal stability of avian paramyxovirus type 1 (APMV-1; virulent APMV-1 strains cause Newcastle disease in poultry) will help inform risk assessments on the presence of viable virus on infected premises or in organic waste from infected premises. In some environments and housing types, heat may also be used as a decontamination method. Therefore, the objective of this study was to characterize the thermal stability (i.e., decimal reduction values [D values]) of APMV-1 in poultry litter. Virus inactivation was evaluated at seven temperatures from 10.0 C through 43.3 C, at 5.5 C intervals (50-110 F. in 10 F intervals), using the I2 isolate of APMV-1, a vaccine strain known to be thermally stable. A high titer of virus (approximately 10~8 50% egg infectious doses) was added to wood shavings based, soiled chicken litter (poultry litter). Litter with both low and high moisture levels were evaluated. Samples were collected at different time intervals, and infectious virus was titrated in embryonated chicken eggs. At high temperatures (37.8 C-43.3 C), infectious virus could not be detected after 2-7 days, whereas at lower temperatures (10 C-21.1 C), it took up to 112 days for virus to decrease to undetectable levels. Furthermore, the D values were almost always shorter in the high moisture litter.
查看更多>>摘要：Infectious bronchitis virus (IBV) is a major pathogen in poultry. The genotypes of IBV vary considerably, and their antigenicity may differ. Nationwide surveillance in South Korea was performed to determine the prevalence and distribution of IBV and its genotypes. By both active and passive surveillance, a total of 939 samples were collected and tested for IBV detection by pathogen-specific reverse transcriptase-PCR. IBV RNA-positive samples were inoculated in embryonated eggs for virus isolation. IBV was genotyped and analyzed phylogenetically based on a partial nucleotide sequence of the S1 gene. A total of 114 IBV strains were isolated; 34 (30.9%) of the 110 samples obtained by passive surveillance, and 80 (9.7%) of the 829 samples obtained by active surveillance, were positive. Most IBVs in both groups were isolated from broilers. Five genotypes (QX-like, B4like, KM91-like, K40/09-like, and 20AD17-like) were observed in South Korea, with the QX-like genotype being the most common, and the 20AD17-like genotype being a novel genotype. These findings will help to maximize protection against IBV infection by providing a reference for the selection of an avian vaccine for IBV in South Korea.
Nitish BansalRenu SinghDeepika ChaudharyNand K. Mahajan...
7页
查看更多>>摘要：Newcastle disease virus (NDV) can infect approximately 250 avian species and causes highly contagious Newcastle disease (ND) in domestic poultry, leading to huge economic losses. There are three different pathotypes of NDV, i.e., lentogenic, mesogenic, and velogenic. Wild resident (wild) and migratory birds are natural reservoirs of NDV and are believed to play a key role in transmitting the virus to domestic poultry. The present study was conducted to determine the prevalence of NDV in wild and migratory birds in the state of Haryana, India, during two migratory seasons (2018-19 and 2019-20). In total 1379 samples (1368 choanal swabs and 11 tissue samples) were collected from live (n=1368) or dead birds (n=4) belonging to 53 different avian species. These samples belonged to apparently healthy (n = 1338), sick (n=30), and dead (n=4) birds. All samples were tested for NDV by real-time reverse transcription-PCR using M gene specific primers and probe. Of the 1379 samples, 23 samples from wild birds [Columba livia domestica (n=12, 52.17%), Pavo cristatus (n=9, 39.13%), and Psittaciformes (n=2, 8.69%)] were found positive for NDV. Only one of the 23 samples (from P. cristatus) was positive for F gene, indicating it to be a mesogenic/ velogenic strain. These results indicate that both lentogenic and velogenic strains of NDV are circulating in wild birds in Haryana and that further studies are needed to characterize NDV strains from wild/migratory birds and domestic poultry to determine the extent of virus transmission among these populations. This study considers the disease transmission risk from domestic pigeons and parrots to commercial poultry and vice versa, and the results emphasize the need for strict biosecurity strategies to protect commercial poultry in the region.
查看更多>>摘要：Vitamin D is a hormone that can be ingested or synthesized in the body when skin is exposed to ultraviolet radiation (UV), typically from sunlight. In captivity, birds with no sunlight exposure may develop vitamin D deficiencies that may contribute to hypocalcemic conditions, even when fed a diet supplemented with vitamin D. An initial pilot study with Hispaniolan Amazon parrots (Amazona ventralis) conducted approximately 18 mo prior indicated there were significant differences in the 25hydroxyvitamin D (vit D) plasma levels between the resident parrots (indoor-only housing) and a new group of historically outdoor-housed parrots (new parrots) 5 days after the arrival of the latter at our institution. The goals of this study were to determine if vit D, ionized calcium (Ca~(2+)), and ionized magnesium (Mg~(2+)) levels changed from baseline values (taken 18 mo prior)in the new birds as well as to compare those values to those of the resident birds over time. The treatment was a change in husbandry for the new parrots (no UV exposure and diet as provided for the resident parrots). To accomplish this, the authors compared vit D levels in the same two groups of birds that were fed the same vit D-fortified diet and given no access to natural or artificial UV light exposure for 18 mo. The resident parrots (N=9) had been housed indoors for approximately 20 yr with no exposure to natural or supplemented UV light. The second group of birds (new parrots; N=8) had been housed outdoors prior to the initiation of the pilot study in 2016 and were fed a similar--but not identical--diet prior to their arrival. Plasma samples were sent to the Michigan State University Diagnostic Center for Population and Animal Health for analysis. Test results demonstrated differences between the two groups of parrots, largely attributed to the decrease in vit D plasma levels in the new parrots over time to values equivalent to those measured in the resident birds. Differences were seen in plasma Ca~(2+), while no differences were demonstrated relative to Mg~(2+). We discuss these findings and suggest that plasma vit D levels decrease in the absence of UV light, even when animals are maintained on a vit D-fortified and balanced diet.
Jessica F. McLaughlinTravis C. GlennKevin WinkerFern Spaulding...
10页
查看更多>>摘要：Avian influenza (AI) is a zoonotic disease that will likely be involved in future pandemics. Because waterbird movements are difficult to quantify, determining the host-specific risk of Eurasian-origin AI movements into North America is challenging. We estimated relative rates of movements, based on long-term evolutionary averages of gene flow, between Eurasian and North American waterbird populations to obtain bidirectional baseline rates of the intercontinental movements of these AI hosts. We used population genomics and coalescent-based demographic models to obtain these gene-flow-based movement estimates. Inferred rates of movement between these continental populations varies greatly among species. Within dabbling ducks, gene flow, relative to effective population size, varies from ~3 to 24 individuals/generation between Eurasian and American wigeons (Mareca penelope and Mareca americana) to ~100-300 individuals/generation between continental populations of northern pintails (Anas acuta). These are evolutionary long-term averages and provide a solid foundation for understanding the relative risks of each of these host species in potential intercontinental AI movements. We scale these values to census size for evaluation in that context. In addition to being AI hosts, many of these bird species are also important in the subsistence diets of Alaskans, increasing the risk of direct bird-to-human exposure to Eurasian-origin AI virus. We contrast species-specific rates of intercontinental movements with the importance of each species in Alaskan diets to understand the relative risk of these taxa to humans. Assuming roughly equivalent AI infection rates among ducks, greater scaup (Aythya marila), mallard (Anas platyrhynchos), and northern pintail (Anas acuta) were the top three species presenting the highest risks for intercontinental AI movement both within the natural system and through exposure to subsistence hunters. Improved data on AI infection rates in this region could further refine these relative risk assessments. These directly comparable, species-based intercontinental movement rates and relative risk rankings should help in modeling, monitoring, and mitigating the impacts of intercontinental host and AI movements.
查看更多>>摘要：The poultry industry needs alternatives to antibiotics, as there are growing public concerns about the emergence of antimicrobial resistance owing to antimicrobial use in animal production. We have reported that the administration of neonatal chicks with synthetic DNA oligodeoxynucleotides containing unmethylated cytosine guanine dinucleotide (CpG) motifs (CpG-ODN) can protect against bacterial pathogens in chickens. The objective of this study was to compare the immunoprotective effects of CpG-ODN and probiotics against Escherichia coli infection vs. commonly used therapeutic antibiotics. Day-old broiler chicks were divided into five groups (n=35/group; 30 for the challenge experiment and 5 for the flow cytometry analysis). The chicks in Group 1 received a single dose of CpG-ODN by the intramuscular route on day 4 (D4) posthatch (PH), and Group 2 received drinking water (DW) with a probiotic product (D1-D15 PH, DW). The Group 3 chicks received tetracycline antibiotics during D9-D13 in DW; the Group 4 chicks got sodium sulfamethazine on D9, D10, and D15 PH in DW; and the Group 5 chicks were administered intramuscular (IM)saline D4 PH, DW. We challenged all the groups (n=30/group) with E. coli (1 × 10~5 or 1 × 10~6 colony-forming units/bird) on D8 PH through the subcutaneous route. Our data demonstrated that the CpG-ODNs, but not the probiotics, could protect neonatal broiler chickens against lethal E. coli septicemia, as would the tetracycline or sodium sulfamethazine. The flow cytometry analysis (n=5/group)revealed enrichment of immune cells in the CpG-ODN group and a marked decrease in macrophages and T-cell numbers in antibioticstreated groups, indicating immunosuppressive effects. Our data showed that, like therapeutic antibiotics, CpG-ODNs reduced clinical signs, decreased bacterial loads, and induced protection in chicks against E. coli septicemia. Unlike therapeutic antibiotics-induced immunosuppressive effects, CpG-ODN caused immune enrichment by increasing chicken immune cells recruitment. Furthermore, this study highlights that, although therapeutic antibiotics can treat bacterial infections, the ensuing immunosuppressive effects may negatively impact the overall chicken health.
查看更多>>摘要：Newcastle disease viruses (NDVs) in Afghanistan were isolated from three chicken farms and identified using a hemagglutination test and reverse transcription-polymerase chain reaction assay. Three isolates from each farm were sequenced to characterize the part of their fusion protein gene around the cleavage site. The characteristics of the fusion protein genes of the three isolates shown by phylogenic analysis indicated that the isolates were velogenic, belonged to the class II subgenotype VII 1.1, and were closely related to an identified Chinese NDV isolate. To our knowledge, this is the first time that NDV isolates from Afghanistan have been partially sequenced.
Mark C. JenkinsCelia O'BrienCarolyn ParkerPeter Thompson...
5页
查看更多>>摘要：The purpose of this study was to compare micro-oocyst counts of Eimeria to PCR analysis of intestinal DNA from smears of duodenum, jejunum/ileum, and cecum of chickens infected with Eimeria acervulina, Eimeria maxima, or Eimeria tenella oocysts. Broiler chicks were infected in triplicate with various doses of E. acervulina, E. maxima, or E. tenella oocysts and were necropsied 5-6 days later to recover duodenal, jejunal, or cecal tissue for micro-oocyst count and for DNA recovery. Micro-oocyst counts were done independently by three individuals. Micro-oocyst counts and PCR directed to ITS1 rDNA or to a single-copy orthologue (SCO 5995) displayed a linear relationship with oocyst dose for each Eimeria species. A strong correlation was found between mean micro-oocyst counts and both PCR assays for E. acervulina (r=0.78-0.94), E. maxima (r=0.79-0.91), and E. tenella (r=0.85-0.96). There was good agreement between ITS1 and SCO 5995 PCR assays: E. acervulina (r=0.92), E. maxima (_r=0.79), and E. tenella (r=0.93). However, only ITS1 PCR analysis corroborated micro-oocyst counts of Eimeria oocyst DNA recovered from Eimeria-infected broiler chickens submitted to a poultry diagnostic laboratory. These findings suggest that ITS1 PCR or SCO PCR can validate traditional micro-oocyst counts used in quantifying Eimeria infection in chickens. Additional studies may provide a method for estimating the relative abundance of each Eimeria species in a natural infection.
Maria Tereza Terra-LongAndrea PietruskaBrigid A. McCreaRuediger Hauck...
7页
查看更多>>摘要：Because of the trend of cage-free egg production, infections with the nematode Ascaridia galli are receiving increased attention. The aim of this study was to establish a timeline for the influence of A. galli on the expression of key cytokines related to a parasitic immune response, and on the composition of the jejunal microbiota. Twenty-eight male layer-type birds were challenged at 24, 25, and 26 days of age. An additional 28 birds were kept as uninfected controls. Starting on Day 31, three birds of each group were euthanized every week until 8 wk postinfection (PI). The number of larvae isolated from the intestinal wall decreased over time, until no larvae were seen at 7 and 8 wk PI. At 5 wk PI, there was a numerical upregulation of all cytokines (TGF-β, IFN-γ, IL-4, IL-8, IL-10, IL-13) in the infected group, but this change was only statistically significant for IL-13. At this time point, larvae were expected to have developed into adults that would have shed eggs in the feces. However, no adult worms were seen and there was no egg shedding. For the microbiota analysis, there were significant differences in the alpha diversity (Faith's phylogenetic diversity) between challenge and control groups, and the beta diversity analysis showed slight differences between samples, suggesting that the age of the birds was the main reason for the separation of groups. These findings suggest that the upregulation of all cytokines evaluated in Week 5 might be the reason for resolution of the infection. Possible explanations are that a high infection dose and the fact that birds were fed with a more nutritionally dense feed might have contributed to the birds' immune system clearing the infection before the worms were able to reach maturity.
查看更多>>摘要：Necrotic enteritis (NE) is a serious disease of chickens and turkeys that causes significant economic losses to the poultry industry. On the basis of studies in chickens, Clostridium perfringens type G is considered by many to be the cause of NE in poultry. However, studies on isolates from Finnish and Italian turkeys with NE revealed that the vast majority were C. perfringens type A, and very few were C. perfringens type G. We therefore examined 74 C. perfringens isolates from U.S. turkeys with NE; 98% were type A and only 1% was type G. This result confirms that different C. perfringens types are involved in NE in turkeys when compared with chickens. We also examined the turkey isolates for other toxin genes associated with enteritis in various animal species, namely tpeL, cpb2, cpe, netE, netF, and netG. The tpeL gene, which has been associated with enhanced virulence of C. perfringens in chickens, was only found in 1% of turkey NE isolates. The cpe gene, which encodes C. perfringens enterotoxin (a major cause of food poisoning and non-foodborne C. perfringens-mediated diarrhea in humans) was also found in only 1% of our turkey NE isolates. Although cpb2, which encodes for the beta2 toxin, was found in 73% of our NE isolates, it has also been found in similar percentages of isolates from turkeys with normal intestine. The netE, netF, and netG genes were not detected among our C. perfringens isolates from turkeys.
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