1
|
Šlapeta J, Ward MP. Embedding research and enquiry in Australian DVM curriculum. Aust Vet J 2024; 102:324-328. [PMID: 38653562 DOI: 10.1111/avj.13334] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 04/01/2024] [Indexed: 04/25/2024]
Abstract
Research and enquiry (R&E) is an integral part of veterinary training. It is a foundation of evidence-based practice. In the University of Sydney Doctor of Veterinary Medicine degree R&E culminates in a cap-stone experience in Year 3: a 'professionally focused project', a student-driven and academic supported individual research project. The project provides an authentic experience within a veterinary discipline. Students work with an academic advisor who provides guidance for developing and achieving meaningful educational and professional goals. Successful advising depends upon a shared understanding of, and commitment to, the advising process by students, advisors and the university. The R&E mission can be broadly defined as - veterinarians recognise that evidence-based approach to practice, which is based on the scientific method, leads to the generation of new knowledge that underpins the veterinary medical profession.
Collapse
Affiliation(s)
- J Šlapeta
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camperdown, New South Wales, Australia
| | - M P Ward
- Sydney School of Veterinary Science, Faculty of Science, The University of Sydney, Camperdown, New South Wales, Australia
| |
Collapse
|
2
|
Abdel-Mawgod S, Zanaty A, Elhusseiny M, Said D, Samir A, Elsayed MM, Mahana O, Said M, Hussein AM, Hassan HM, Selim A, Shahien MA, Selim K. Genetic heterogeneity of chicken anemia virus isolated in selected Egyptian provinces as a preliminary investigation. Front Vet Sci 2024; 11:1362219. [PMID: 38840626 PMCID: PMC11150715 DOI: 10.3389/fvets.2024.1362219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 04/29/2024] [Indexed: 06/07/2024] Open
Abstract
Chicken anemia virus (CAV) is a widespread and economically significant pathogen in the poultry industry. In this study 110 samples were collected from various poultry farms in selected Egyptian provinces during 2021-2022 and were tested against CAV by Polymerase Chain Reaction (PCR), revealing 22 positive samples with 20% incidence rate. Full sequence analysis of five selected CAV strains revealed genetic variations in VP1, VP2, and VP3 genes. Phylogenetic analysis grouped the Egyptian strains with reference viruses, mainly in group II, while vaccines like Del-Rose were categorized in group III. Recombination events were detected between an Egyptian strain (genotype II) and the Del-Rose vaccine strain (genotype III), indicating potential recombination between live vaccine strains and field isolates. To evaluate pathogenicity, one Egyptian isolate (F883-2022 CAV) and Del-Rose vaccine were tested in Specific Pathogen Free (SPF) chicks. Chicks in the positive group displayed clinical symptoms, including weakness and stunted growth, with postmortem findings consistent with CAV infection. The vaccine group showed milder symptoms and less severe postmortem changes. This study provides important insights into the genetic diversity of CAV in selected Egyptian poultry farms showing recombination event between field strain and vaccine strains, highlighting the need for advanced vaccination programs, especially for broilers.
Collapse
Affiliation(s)
- Sara Abdel-Mawgod
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Ali Zanaty
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Mohamed Elhusseiny
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Dalia Said
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Abdelhafez Samir
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Moataz M. Elsayed
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Osama Mahana
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Mahmoud Said
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Ahmed M. Hussein
- Division of Pharmacology and Toxicology, Department of Pharmaceutical Sciences, University of Vienna, Vienna, Austria
| | - Heba M. Hassan
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Abdullah Selim
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Momtaz A. Shahien
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| | - Karim Selim
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center, Giza, Egypt
| |
Collapse
|
3
|
Assen AM, Gerber PF, Walkden-Brown SW. Protection Efficacy of the Infectious Laryngotracheitis (ILT) Serva CEO Vaccine Strain in Broiler Chickens Under Different Vaccination Coverage Conditions. Avian Dis 2023; 67:160-169. [PMID: 37556295 DOI: 10.1637/aviandiseases-d-22-00050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2022] [Accepted: 05/03/2023] [Indexed: 08/11/2023]
Abstract
Mass vaccination against infectious laryngotracheitis virus (ILTV) in drinking water can result in variable initial vaccine take. Partial initial vaccine coverage of 20% with an Australian ILT vaccine (A20) previously resulted in significant protection against virulent ILTV challenge. This follow-up study used the international Serva ILT vaccine strain in a factorial design testing four levels of vaccination coverage (0%, 10%, 20%, or 100% of chicks eye-drop vaccinated with the live vaccine at 7 days of age) and three levels of ILTV challenge (no challenge or challenge at 7 or 21 days postvaccination [DPV]). The increase in ILTV load in choanal cleft swabs detected by qPCR after challenge was significantly reduced by 20% and 100% but not by 10% vaccination coverage. Vaccination reduced weight gain in unchallenged birds. Daily weight gain of birds was not affected by ILTV challenge at 7 DPV in any group, but following challenge at 21 DPV, it was significantly reduced in unvaccinated and 10% vaccinated groups relative to 20% and 100% vaccinated groups. Vaccination of 20% of the chickens provided substantial but incomplete protection (protective index range 44%-70%) against the severity of clinical signs and mortality following challenge while 10% vaccination coverage provided limited or no protection. Clinical signs were more severe and appeared earlier following challenge at 21 DPV than at 7 DPV. Within the vaccination treatments, eye-drop-vaccinated birds were better protected than their in-contact cohorts. In conclusion, partial vaccination of 20%, but not 10% of chickens, induced substantial protection against subsequent challenge. However, the attendant risks of reduced protection against early challenge and the possible reversion to virulence of vaccine virus when transmitted to unvaccinated chickens make it essential that 100% initial vaccine take be the goal of mass vaccination programs.
Collapse
Affiliation(s)
- Awol M Assen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia, ,
- School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| |
Collapse
|
4
|
mossad Z, Moussa SA, Saied M, Fathy MM, Zanaty AM. Molecular and genetic detection of infectious laryngeotrachitis disease virus in broiler farms after a disease outbreak in Egypt. Virusdisease 2022; 33:404-412. [PMID: 36447812 PMCID: PMC9701306 DOI: 10.1007/s13337-022-00792-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Accepted: 08/22/2022] [Indexed: 11/30/2022] Open
Abstract
Infectious laryngotracheitis (ILT) is a viral respiratory illness in poultry that causes massive financial losses. This research aimed to isolate and identify the ILT virus in suspected outbreaks of broiler flocks in Egypt during 2020-2021, besides investigating its genetic link with other circulating strains. Real-time-PCR was used to test 57 samples taken from unvaccinated broiler farms. Ten samples are positive for ILTV, and the virus is being isolated in SPF chicken embryos. The Sanger sequencing was used to conduct (partial) sequencing of the infected cell protein4 gene (ICP4) for eight isolates. Phylogenetic analysis conducted Maximum Likelihood, comparative sequencing analysis of ICP4 of strains under study with vaccination ILT reference strains reveled that all isolates were clustered into two major groups. The (OM291843and OM291846) clustered together with the chicken embryo origin vaccine strains (IV and V group). The remaining six strains belong to the TCO vaccine(I, II and III group). The total sequence similarity between the strains under study and the various Egyptian strains varied from (97 to 100%) while the similarity with TCO or chicken embryo origin -vaccine strains ranged from (95to 100%). There were no deletions detected in the 272-283-bp region of the ICP4 gene. Detection of arginine to methionine substitutions at position 180 (R180M) and change of Serine to Asparagine at position 227 (S227N) in the (OM291843 and OM291846) which were previously described in chicken embryo origin -vaccine strains. This reveals that field strains may have evolved from vaccine strains, notably identification of non-synonymous substitutions which might be linked to the virulence strains' attenuation. Finally, independent of geographical distribution, both chicken embryo origin-vaccine-like and TCO-Vaccine-like virus strains were circulating in Egyptian non-vaccinated broiler flocks in 2020 and 2021. Despite their genetic differences, both viruses caused significant illnesses in the field.
Collapse
Affiliation(s)
- Zienab mossad
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center (ARC), 12618 Giza, Egypt
| | - Saad A. Moussa
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center (ARC), 12618 Giza, Egypt
| | - M. Saied
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center (ARC), 12618 Giza, Egypt
| | - Mustafa M. Fathy
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center (ARC), 12618 Giza, Egypt
| | - Ali Mahmoud Zanaty
- Reference Laboratory for Veterinary Quality Control on Poultry Production, Animal Health Research Institute, Agriculture Research Center (ARC), 12618 Giza, Egypt
| |
Collapse
|
5
|
Assen AM, Groves PJ, Etherington A, Gerber PF, Sexton M, Williamson S, Walkden-Brown SW. Field Application of qPCR Monitoring of Infectious Laryngotracheitis Virus in Settled Chicken House Dust and Its Role in Control of a Major Outbreak. Avian Dis 2022; 66:1-9. [PMID: 36106910 DOI: 10.1637/aviandiseases-d-22-00022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2022] [Accepted: 06/06/2022] [Indexed: 12/14/2022]
Abstract
Population-level sampling based on qPCR detection of infectious laryngotracheitis virus (ILTV) in poultry dust can be used to assess ILT vaccination outcomes following mass administration in drinking water. We report on the field application of this approach to assess the success of vaccine administration and its use in ILT outbreak control in meat chickens. In Study 1, dust samples were collected from 26 meat chicken flocks at 0, 4, 7, 14, and 21 days post drinking water vaccination (DPV) given between 7 to 13 days of age with the Serva or A20 live attenuated ILT vaccines. Unexpectedly, ILTV DNA was detected in dust samples collected prior to vaccination in 22/26 flocks. Typing revealed that the detected ILTV was different from the vaccine virus. To determine whether the detected ILTV DNA was from active infection or carryover of a noninfectious virus, Study 2 was implemented in 14 additional flocks with dust samples collected at 0, 7, 14, and 21 DPV and tracheal swabs collected from 15 birds/flock at 0 and 21 DPV. The results indicated that there was active infection with ILTV in those flocks before vaccination. This approach contributed to a statewide control program resulting in the eradication of ILT from South Australia as confirmed by negative ILTV test results for dust samples from 50 flocks and the absence of clinical ILT. These findings show that ILTV infection prior to vaccination is common in outbreak situations and that dust samples must be collected at 0 and 7 DPV for meaningful interpretation of vaccination outcomes and ILTV status. Comparatively low-cost dust testing during an outbreak, coupled with typing information, greatly assisted with decision making and control strategies during a major outbreak, including confirmation of the absence of infection in the final stages.
Collapse
Affiliation(s)
- Awol M Assen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia, , , .,School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Peter J Groves
- Sydney School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia
| | | | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - Margaret Sexton
- Biosecurity SA, Department of Primary Industries and Regions SA, Glenside, SA 5065, Australia
| | | | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| |
Collapse
|
6
|
Assen AM, Yegoraw AA, Walkden-Brown SW, Gerber PF. Molecular-based monitoring of live vaccines in dust samples from experimental and commercial chicken flocks and its potential use as a screening test. Res Vet Sci 2021; 143:50-57. [PMID: 34973539 DOI: 10.1016/j.rvsc.2021.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 11/27/2021] [Accepted: 12/16/2021] [Indexed: 11/17/2022]
Abstract
Despite the high cost of vaccination programmes, conventional methods to evaluate vaccine uptake are often impractical and costly. More recently, molecular-based testing of poultry dust has been used to monitor the "take" of Marek's disease virus and infectious laryngotracheitis virus (ILTV) live vaccines. This study aimed to provide proof-of-concept for detecting other poultry pathogens by using molecular detection of vaccine microorganisms in poultry dust of vaccinated flocks. Dust and choanal cleft and cloacal swabs were collected from chickens vaccinated against avian encephalomyelitis virus (AEV), fowlpox virus (FPV), Mycoplasma gallisepticum (MG) and Mycoplasma synoviae (MS) using live vaccines in an experimental flock. Dust samples were collected weekly from 5 commercial breeder or layer flocks from day-old up to 25 weeks of age. These flocks were vaccinated against Newcastle disease virus (NDV), infectious bronchitis virus (IBV), infectious bursal disease virus (IBDV), ILTV, fowl adenovirus (FAdV), MG and MS. Samples were tested for nucleic acids of these microorganisms by PCR or reverse transcriptase PCR. Genomes of all targeted vaccines were detected in dust samples from the experimental and commercial flocks except for FPV, which was detected only in the experimental flock. FAdV was detected in unvaccinated commercial flocks. These findings suggest that PCR detection of target organisms in dust samples has potential as a relatively simple and inexpensive population-level test to monitor vaccine take and/or pathogen status in chicken flocks. Further studies comparing the detection of each of these microorganisms in poultry dust with individual birds samples are required to validate this approach.
Collapse
Affiliation(s)
- Awol M Assen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Addisu A Yegoraw
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; School of Veterinary Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia.
| |
Collapse
|
7
|
Tran TT, Yegoraw AA, Assen AM, Walkden-Brown SW, Gerber PF. Genomic Stability for PCR Detection of Infectious Laryngotracheitis Virus and Infectious Bronchitis Virus in Poultry Dust Samples Stored Under Different Conditions. Avian Dis 2021; 64:565-570. [PMID: 33647150 DOI: 10.1637/0005-2086-64.4.565] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Accepted: 08/12/2020] [Indexed: 11/05/2022]
Abstract
Dust collected from the poultry house has been increasingly used as a population-level sample to monitor the presence of pathogens or to evaluate the administration of live vaccines. However, there are no guidelines for the storage of this sample type. This study investigated the stability of infectious laryngotracheitis virus (ILTV), a DNA virus, and infectious bronchitis virus (IBV), an RNA virus, in poultry dust kept under temperature and moisture conditions that mimic on-farm and laboratory storage. Dust samples were collected from chicks spray vaccinated with a live IBV vaccine and inoculated with a field ILTV strain via eye drop. Samples were stored under different moisture conditions (dry = 2% moisture, moist = 22%-71% moisture) and temperatures (-20, 4, 25, and 37 C) for different durations (0, 7, and 14 days, and 1, 2, 3, and 4 mo) in a factorial arrangement, followed by quantitative PCR for detection of virus genome copies (GC). The length of storage, moisture level, and storage temperature affected the viral genome load for ILTV and IBV but did not affect the number of positive samples for each virus. All treatment combinations were ILTV positive for at least 4 mo. In dry dust samples, all storage temperatures or durations had quantifiable ILTV or IBV GC. Moisture addition had a detrimental effect on viral genome load, causing an overall reduction of 0.3 log 10 for ILTV GC (7.29 and 6.97 log 10, P = 0.0001), and 1.3 log 10 for IBV GC (5.95 and 4.66 log 10, P = 0.0001), which are unlikely to have biologic significance. In conclusion, dry dust can be stored at any temperature up to 37 C for at least 4 mo without loss in qPCR detection of ILTV or IBV GC. Collection or storage of moist dust should be avoided, or air drying prior to storage is recommended if only moist dust is available.
Collapse
Affiliation(s)
- Thanh T Tran
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia, 2351.,Faculty of Animal Sciences and Veterinary Medicine, Nong Lam University, Ho Chi Minh City, Vietnam
| | - Addisu A Yegoraw
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia, 2351.,School of Veterinary Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia
| | - Awol M Assen
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia, 2351.,School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Stephen W Walkden-Brown
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia, 2351
| | - P F Gerber
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia, 2351
| |
Collapse
|
8
|
Yegoraw AA, Assen AM, Gerber PF, Walkden-Brown SW. Transmission of infectious laryngotracheitis virus vaccine and field strains: the role of degree of contact and transmission by whole blood, plasma and poultry dust. Vet Res 2021; 52:91. [PMID: 34158102 PMCID: PMC8220770 DOI: 10.1186/s13567-021-00959-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 06/03/2021] [Indexed: 11/17/2022] Open
Abstract
Understanding the mechanisms of transmission of infectious laryngotracheitis virus (ILTV) is critical to proper control as both vaccine and wild-type strains circulate within chicken flocks with potential adverse consequences. The relative efficiency of transmission by direct contact between chickens and airborne transmission has not been investigated. Furthermore, relatively high levels of ILTV DNA have been detected in poultry dust and blood but the infectivity of these is unknown. In this study, comparison of in-contact and airborne transmission of two vaccine and one field strain of ILTV revealed that all transmitted to 100% of in-contact birds by 6 days post-exposure (dpe). Airborne transmission without contact resulted in 100% transmission by 14 and 17 dpe for the wild-type and Serva vaccine virus but only 27% transmission by 21 dpe for the A20 vaccine virus. The infectivity of dust or extracts of dust and blood or plasma from infected chickens at various stages of infection was assessed by inoculation into susceptible chickens. There was no transmission by any of these materials. In conclusion, direct contact facilitated efficient ILTV transmission but the virus was unable to be transmitted by dust from infected chickens suggestive of a limited role in the epidemiology of ILTV.
Collapse
Affiliation(s)
- Addisu A Yegoraw
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia.
- School of Veterinary Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia.
| | - Awol M Assen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
- School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| |
Collapse
|
9
|
Assen AM, Walkden-Brown SW, Stillman M, Alfirevich S, Gerber PF. Comparison of tracheal and choanal cleft swabs and poultry dust samples for detection of Newcastle disease virus and infectious bronchitis virus genome in vaccinated meat chicken flocks. PLoS One 2021; 16:e0247729. [PMID: 33861761 PMCID: PMC8051787 DOI: 10.1371/journal.pone.0247729] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/13/2021] [Indexed: 02/08/2023] Open
Abstract
This study assessed different methods (tracheal and choanal cleft swabs from individual birds, and poultry dust as a population level measure) to evaluate the shedding kinetics of infectious bronchitis virus (IBV) and Newcastle disease virus (NDV) genome in meat chicken flocks after spray vaccination at hatchery. Dust samples and tracheal and choanal cleft swabs were collected from four meat chicken flocks at 10, 14, 21 and 31 days post vaccination (dpv) and tested for IBV and NDV genome copies (GC) by reverse transcriptase (RT)-PCR. IBV and NDV GC were detected in all sample types throughout the study period. Detection rates for choanal cleft and tracheal swabs were comparable, with moderate and fair agreement between sample types for IBV (McNemar's = 0.27, kappa = 0.44) and NDV (McNemar's = 0.09; kappa = 0.31) GC respectively. There was no significant association for IBV GC in swabs and dust samples (R2 = 0.15, P = 0.13) but NDV detection rates and viral load in swabs were strongly associated with NDV GC in dust samples (R2 = 0.86 and R2 = 0.90, P<0.001). There was no difference in IBV and NDV GC in dust samples collected from different locations within a poultry house. In conclusion, dust samples collected from any location within poultry house show promise for monitoring IBV and NDV GC in meat chickens at a population level and choanal cleft swabs can be used for detection of IBV and NDV GC instead of tracheal swabs in individual birds.
Collapse
Affiliation(s)
- Awol M. Assen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
- School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Stephen W. Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
| | - Mark Stillman
- Baiada Poultry Pty Limited, New South Wales, Australia
| | | | - Priscilla F. Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, New South Wales, Australia
- * E-mail:
| |
Collapse
|
10
|
Genetic Heterogeneity among Chicken Infectious Anemia Viruses Detected in Italian Fowl. Animals (Basel) 2021; 11:ani11040944. [PMID: 33801597 PMCID: PMC8067058 DOI: 10.3390/ani11040944] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/20/2021] [Accepted: 03/24/2021] [Indexed: 01/20/2023] Open
Abstract
Chicken infectious anemia virus (CIAV) is a pathogen of chickens associated with immunosuppression and with a disease named chicken infectious anemia. The present survey reports an epidemiological study on CIAV distribution in Italian broiler, broiler breeder and backyard chicken flocks. Twenty-five strains were detected by a specifically developed nested PCR protocol, and molecularly characterized by partial VP1 gene or complete genome sequencing. Viral DNA amplification was successfully obtained from non-invasive samples such as feathers and environmental dust. Sequence and phylogenetic analysis showed the circulation of field or potentially vaccine-derived strains with heterogeneous sequences clustered into genogroups II, IIIa, and IIIb. Marker genome positions, reported to be correlated with CIAV virulence, were evaluated in field strains. In conclusion, this is the first survey focused on the molecular characteristics of Italian CIAVs, which have proved to be highly heterogeneous, implementing at the same time a distribution map of field viruses worldwide.
Collapse
|
11
|
Tran TT, Nazir S, Yegoraw AA, Assen AM, Walkden-Brown SW, Gerber PF. Detection of infectious laryngotracheitis virus (ILTV) in tissues and blood fractions from experimentally infected chickens using PCR and immunostaining analyses. Res Vet Sci 2020; 134:64-68. [PMID: 33310555 DOI: 10.1016/j.rvsc.2020.11.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 11/24/2020] [Accepted: 11/29/2020] [Indexed: 10/22/2022]
Abstract
The ability of infectious laryngotracheitis virus (ILTV) to replicate in organs outside of the upper respiratory tract and conjunctiva associated-lymphoid tissues is still not well understood. This study investigated the tissue distribution of an Australian field strain of ILTV (class 9) on birds experimentally inoculated via eye-drop at 7 days of age by using quantitative PCR (qPCR) and immunohistochemistry. Tissues including conjunctiva, caecal tonsil, kidney, liver, lung, spleen, thymus, trachea and blood were collected from sham-inoculated (control group; n = 2) and ILTV-inoculated (n = 8) birds at 7 days post-inoculation (dpi). Blood was collected from 13 infected birds at 14 dpi and fractionated using ficoll-paque. At 7 dpi, the highest detection rate and genomic copies (GC) were in conjunctiva (8/8; 8.08 ± 0.48 log10 GC/mg) followed by trachea (8/8; 4.64 ± 0.48) and thymus (8/8; 4.52 ± 0.48), kidney (8/8; 3.97 ± 0.48), lung (8/8; 3.65 ± 0.48), spleen (8/8; 3.55 ± 0.48), liver (8/8; 3.51 ± 0.48), caecal tonsil (7/8; 3.76 ± 0.48) and plasma (4/8; 2.40 ± 0.48 log10 GC/ml). ILTV antigen was only detected in conjunctiva (7/8), trachea (6/8) and lung (4/8) samples. At 14 dpi, ILTV detection rate and genomic copies in buffy coat cells were 12/13 and 2.86 ± 0.39 log10 GC/mg, respectively while those of plasma were 11/13 and 4.29 ± 0.39 log10 GC/ml and red blood cell were 3/13 and 0.36 ± 0.39 log10 GC/mg. In conclusion, ILTV DNA was detected in a wide range of tissues and blood fractions but ILTV antigen was only detected in respiratory organs and conjunctiva.
Collapse
Affiliation(s)
- Thanh T Tran
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia; Faculty of Animal Science and Veterinary Medicine, Nong Lam University, Ho Chi Minh City, Viet Nam
| | - Shahid Nazir
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Addisu A Yegoraw
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia; School of Veterinary Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia
| | - Awol M Assen
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia; School of Veterinary Medicine, Wollo University, Dessie, Ethiopia
| | - Stephen W Walkden-Brown
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia
| | - Priscilla F Gerber
- School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.
| |
Collapse
|
12
|
Analysis of Whole-Genome Sequences of Infectious laryngotracheitis Virus Isolates from Poultry Flocks in Canada: Evidence of Recombination. Viruses 2020; 12:v12111302. [PMID: 33198373 PMCID: PMC7696358 DOI: 10.3390/v12111302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 10/30/2020] [Accepted: 11/10/2020] [Indexed: 01/09/2023] Open
Abstract
Infectious laryngotracheitis virus (ILTV) is a herpes virus that causes an acute respiratory disease of poultry known as infectious laryngotracheitis (ILT). Chicken embryo origin (CEO) and tissue culture origin (TCO) live attenuated vaccines are routinely used for the control of ILT. However, vaccine virus is known to revert to virulence, and it has been recently shown that ILT field viral strains can undergo recombination with vaccinal ILTV and such recombinant ILT viruses possess greater transmission and pathogenicity potential. Based on complete or partial genes of the ILTV genome, few studies genotyped ILTV strains circulating in Canada, and so far, information is scarce on whole-genome sequencing or the presence of recombination in Canadian ILTV isolates. The objective of this study was to genetically characterize the 14 ILTV isolates that originated from three provinces in Canada (Alberta, British Columbia and Quebec). To this end, a phylogenetic analysis of 50 ILTV complete genome sequences, including 14 sequences of Canadian origin, was carried out. Additional phylogenetic analysis of the unique long, unique short and inverted repeat regions of the ILTV genome was also performed. We observed that 71%, 21% and 7% of the ILTV isolates were categorized as CEO revertant, wild-type and TCO vaccine-related, respectively. The sequences were also analyzed for potential recombination events, which included evidence in the British Columbia ILTV isolate. This event involved two ILTV vaccine (CEO) strains as parental strains. Recombination analysis also identified that one ILTV isolate from Alberta as a potential parental strain for a United States origin ILTV isolate. The positions of the possible recombination breakpoints were identified. These results indicate that the ILTV wild-type strains can recombine with vaccinal strains complicating vaccine-mediated control of ILT. Further studies on the pathogenicity of these ILTV strains, including the recombinant ILTV isolate are currently ongoing.
Collapse
|
13
|
Assen AM, Stillman M, Alfirevich S, Gerber PF, Groves PJ, Walkden-Brown SW. Assessment of A20 infectious laryngotracheitis vaccine take in meat chickens using swab and dust samples following mass vaccination in drinking water. Vet Microbiol 2020; 251:108903. [PMID: 33176212 DOI: 10.1016/j.vetmic.2020.108903] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 10/18/2020] [Indexed: 01/24/2023]
Abstract
Infectious laryngotracheitis, caused by the alphaherpesvirus infectious laryngotracheitis virus (ILTV), is an important disease of chickens. Partial control of this disease in meat chickens is commonly achieved by mass vaccination with live virus in drinking water. There is a need for a practical test to evaluate vaccination outcomes. For the Serva ILTV vaccine, quantitative real-time PCR (qPCR) enumeration of ILTV genome copies (GC) in flock level dust samples collected at 7-8 days post vaccination (dpv) can be used to differentiate flocks with poor and better vaccine take. This study aimed to validate this approach for A20, another widely used ILT vaccine in Australia. In four meat chicken flocks vaccinated with A20 in water using two different water stabilization times (20 or 40 min), swabs from the trachea and choanal cleft and dust samples were collected at 0, 7, 14 and 21 dpv. ILTV GC detection in swabs and dust was highest at 7 dpv and at this time ILTV GC load in dust was strongly and positively associated with vaccine take in individual birds assessed by swab samples. Choanal cleft swabs provided significantly fewer ILTV positive results than paired tracheal swab samples but the level of ILTV GC detected was similar. Water stabilization time had only minor effects on vaccination response in favour of the shorter time. Location of dust collection had no effect on viral load measured in dust samples. Dust samples collected at 0 and 7 dpv can be used to assess the vaccination status of flocks.
Collapse
Affiliation(s)
- Awol M Assen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia; School of Veterinary Medicine, Wollo University, Dessie, Ethiopia.
| | | | | | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Peter J Groves
- Poultry Research Foundation, School of Veterinary Science, University of Sydney, NSW, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| |
Collapse
|
14
|
Nazir S, Yegoraw AA, Charlesworth RPG, Williamson S, Sharpe S, Walkden-Brown SW, Gerber PF. Marked differences in virulence of three Australian field isolates of infectious laryngotracheitis virus in meat and layer chickens. Avian Pathol 2020; 49:600-610. [PMID: 32720515 DOI: 10.1080/03079457.2020.1801987] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
The objectives of this study were to compare the virulence of contemporary infectious laryngotracheitis virus (ILTV) field isolates of classes 9, 10, and 14 in meat and layer chickens, and to evaluate cloacal and oropharyngeal swabs and dust as sample types for ILTV detection. A total of 211 chickens were divided into groups and inoculated with ILTV class 9, 10, or 14, or sham-inoculated via eye drop at 15 or 22 days of age. Chickens were euthanized at 5 and 9 days post-infection. Virulence was assessed by scoring of clinical signs (conjunctivitis, dyspnoea, and demeanour), ILTV genomic copies (GC) in oropharyngeal and cloacal swabs, mortality and microscopic lesions in conjunctiva and trachea. Class 14 caused subclinical infection, while inoculation with class 9 or class 10 resulted in severe clinical signs and microscopic lesions. Compared to class 14 (2.25 ± 0.36 log10 GC), higher viral load was observed in oropharyngeal swabs of classes 9 (7.86 ± 0.48) and 10 (7.53 ± 0.36), with a higher proportion of positive oropharyngeal and cloacal swabs in the latter groups (P < 0.0001). Viral detection in cloacal swabs was delayed at early stages of infection compared to oropharyngeal swabs. Dust samples from class 9- and class 10-inoculated groups showed a trend towards higher GC than that of class 14. Overall, clinical scores, mortality, viral load, and microscopic lesions were similar for classes 9 and 10, but class 9 caused more severe disease in layer chickens than meat chickens. In summary, ILTV classes 9 and 10 exhibited severe virulence, while class 14 exhibited very mild virulence. RESEARCH HIGHLIGHTS Wide variation in the virulence of three field Australian field ILTV strains. Class 9 and class 10 strains were highly virulent, while class 14 was mildly virulent. The highly virulent strains were associated with significantly higher viral genome copies in various sample types than the mildly virulent strain.
Collapse
Affiliation(s)
- Shahid Nazir
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, Australia
| | - Addisu A Yegoraw
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, Australia.,School of Veterinary Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia
| | | | | | - Sue Sharpe
- Birling Avian Laboratories, Bringelly, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, Australia
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, Australia
| |
Collapse
|
15
|
Yegoraw AA, Nazir S, Gerber PF, Walkden-Brown SW. Airborne Transmission of Vaccinal and Wild Type Infectious Laryngotracheitis Virus and Noninfectivity of Extracts of Excreta from Infected Chickens. Avian Dis 2020; 65:30-39. [PMID: 34339119 DOI: 10.1637/aviandiseases-d-20-00073] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 08/27/2020] [Indexed: 11/05/2022]
Abstract
Infectious laryngotracheitis virus (ILTV) is thought to exit the host in respiratory aerosols and enter by inhalation of these. High levels of ILTV DNA have been detected in excreta, raising the possibility of alternative routes of shedding from the host. However, it is not known whether or not the ILTV DNA in excreta represents infective virus. This study investigated transmission of wild type and vaccinal ILTV from infected to susceptible commercial meat chickens. Airborne- and excreta-mediated transmission of two field isolates of ILTV (Classes 9 and 10) and three vaccine strains (SA2, A20, and Serva) were tested. To test airborne transmission, air from isolators containing infected birds was ducted through a paired isolator containing uninfected chickens. To test excreta transmission, aliquots were prepared from excreta containing a high level of ILTV DNA within the first week after infection. Chicks were infected bilaterally by eye drop. Clinical signs were monitored daily and choanal cleft swab samples for ILTV detection by quantitative PCR were collected at 4, 8, 15, 22, and 28 days postinfection (DPI) in the airborne transmission study and at 7 and 14 DPI from the excreta transmission studies. There was no transmission of ILTV from excreta, suggesting that ILTV is inactivated during passage through the gut. All strains of ILTV were transmitted by the airborne route but only to a limited extent for the vaccine viruses. The field viruses induced clinical signs, pathology, and greatly elevated ILTV genome copies in swabs. In summary, these findings confirm the suspected airborne transmission of ILTV, demonstrate differential transmission potential between wild type and vaccine strains by this route, and indicate that excreta is unlikely to be important in the transmission of ILTV and the epidemiology of ILT.
Collapse
Affiliation(s)
- Addisu Awukew Yegoraw
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia, .,School of Veterinary Medicine, Wolaita Sodo University, Wolaita Sodo, Ethiopia
| | - Shahid Nazir
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| |
Collapse
|
16
|
Ahaduzzaman M, Groves PJ, Sharpe SM, Williamson SL, Gao YK, Nguyen TV, Gerber PF, Walkden-Brown SW. A practical method for assessing infectious laryngotracheitis vaccine take in broilers following mass administration in water: Spatial and temporal variation in viral genome content of poultry dust after vaccination. Vet Microbiol 2019; 241:108545. [PMID: 31928697 DOI: 10.1016/j.vetmic.2019.108545] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 02/08/2023]
Abstract
Infectious laryngotracheitis is an important disease of chickens caused by infectious laryngotracheitis virus (ILTV). Outbreaks commonly occur in meat chicken flocks and mass vaccination with live attenuated vaccines, usually in water, is used to control the disease in these populations. Vaccination with live virus via water and nipple drinkers requires stringent adherence to protocols to ensure success, but vaccine administration monitoring is not currently assessed due to a lack of economically viable methods. Vaccinal ILTV has been shown to be detectable in dust in experimental studies and has potential as a method of assessing vaccination success. However, the pattern of vaccinal ILTV detection in dust following vaccination under commercial conditions has not been defined. We report the longitudinal profile of ILTV genome copies (GC) in poultry house dust collected on settle plates following vaccination of 8 flocks of commercial meat chickens on four farms. ILTV GC was enumerated using quantitative real-time polymerase chain reaction (qPCR). There was considerable variation between flocks in the levels of ILTV GC detected post vaccination and this variation was significantly associated with vaccine take measured in individual birds in a companion study. There was no effect of sampling location on ILTV GC in dust but the amount of dust collected was greater in locations closer to the exhaust fans in artificially ventilated houses. Results indicate that measurement of ILTV GC in single or pooled dust samples at 7-8 days post vaccination enables detection of poor vaccine takes and provides a practical means of monitoring ILT vaccination.
Collapse
Affiliation(s)
- Md Ahaduzzaman
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; Faculty of Veterinary Medicine, Chattogram Veterinary and Animal Sciences University, Chattogram, 4225, Bangladesh.
| | - Peter J Groves
- Sydney School of Veterinary Science, The University of Sydney, Camden, NSW 2570, Australia; Zootechny Pty Ltd, Austral, NSW, Australia
| | - Sue M Sharpe
- Birling Avian Laboratories, Bringelly, NSW, Australia
| | | | | | - Trong V Nguyen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia; Faculty of Animal Science and Veterinary Medicine, Tay Nguyen University, 567 Le Duan, Buon Ma Thuot, Đak Lak, Viet Nam
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW 2351, Australia
| |
Collapse
|
17
|
Nguyen TV, Ahaduzzaman M, Campbell DLM, Groves PJ, Walkden-Brown SW, Gerber PF. Spatial and temporal variation of Marek's disease virus and infectious laryngotracheitis virus genome in dust samples following live vaccination of layer flocks. Vet Microbiol 2019; 236:108393. [PMID: 31500729 DOI: 10.1016/j.vetmic.2019.108393] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Revised: 08/09/2019] [Accepted: 08/18/2019] [Indexed: 10/26/2022]
Abstract
Monitoring of Marek's disease virus (MDV) and infectious laryngotracheitis virus (ILTV) genome using poultry dust can be useful to monitor on-farm vaccination protocols but there are no set guidelines for collection of this sample type. This study assessed different dust collection methods for MDV and ILTV detection in a vaccinated layer flock (n = 1700) from day-old to 50 weeks of age. Birds were vaccinated against MDV at day-old, and ILTV by drinking water at week 6 and eye drop at week 12. Dust samples were collected weekly by settle plates (1-3 plates/15 m2) or by scraping surfaces in the poultry shed and tested for ILTV and MDV genomic copies (GC) by PCR. ILTV GC were detected 4 weeks post water vaccination, peaked at weeks 12-14 and became mostly undetectable after week 18. MDV was detected in dust on week 1, peaked at weeks 3-6, declined 3 logs by week 26 and remained detectable at this level until week 50. There was no difference in the detection rates of ILTV and MDV collected from settle plates in different locations of the shed (P > 0.10). There was no difference between settle plate and scraped samples in ILTV GC load but higher MDV GC were found in scraped samples. The settle plate method appears to reflect the current level of vaccine virus in the flock while the scrape method likely represents a cumulative record of shedding. Assessment of viral GC in dust samples is a good candidate for a practical method of estimating successful vaccine administration.
Collapse
Affiliation(s)
- Trong V Nguyen
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia; Faculty of Animal Science and Veterinary Medicine, Tay Nguyen University, Buon Ma Thuot, Dak Lak, Viet Nam
| | - M Ahaduzzaman
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia; Faculty of Veterinary Medicine, Chattogram Veterinary and Animal Sciences University, Chattogram, Bangladesh
| | - Dana L M Campbell
- Agriculture and Food, Commonwealth Scientific and Industrial Research Organisation, Armidale, NSW, Australia
| | - Peter J Groves
- Faculty of Veterinary Science, The University of Sydney, Camden, NSW, Australia
| | - Stephen W Walkden-Brown
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia
| | - Priscilla F Gerber
- Animal Science, School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia.
| |
Collapse
|