Dr. Leonardo Susta
  • Office
  • PAHL 4800
  • 54323
  • Lab:
  • PAHL 4811
  • 54640


After earning his veterinary degree, Dr. Susta spent the last 7 years working on high-consequence poultry diseases at the University of Georgia, where he earned his doctorate, and at the Southeast Poultry Research Laboratory (USDA-ARS), where he worked for two and a half years as research associate. Dr. Susta has worked extensively on the molecular characterization and clinico-pathological assessment of Newcastle disease virus (NDV) and avian influenza virus (AIV) isolates in multiple avian species.  Another area of Dr. Susta's research included production of recombinant NDV clones in order to dissect NDV immunopathogenesis, and to evaluate the use of cytokines to enhance immune response to vaccination. As a board certified veterinary pathologist, Dr. Susta has extensive experience in diagnostic pathology of common poultry species.

At the University of Guelph, and as a member of the Poultry Health Research Network, Dr. Susta is establishing a research program that focuses on multiple infectious diseases of avian species, with particular emphasis for commercial and backyard poultry.  Dr. Susta’s work will include applied research for the development of more effective vaccine strategies, surveillance of important poultry pathogens in Ontario, and validation of next-generation sequencing for quick and reliable full-genome sequencing of important poultry viruses.  Basic research will be conducted to dissect the determinant of resistance avian pathogens, and to investigate quasispecies mutant spectra of avian viruses such as AIV and NDV.  

This lab seeks highly motivated researchers and students who have interest in the study of veterinary/avian virology and in learning the basic mechanisms of viral pathogenesis through in vitro and in vivo experiments.  In addition to in-depth training in pathology, trainees will gain experience in multiple areas of virology, including reverse genetics of RNA viruses, evaluation of genetic determinant of resistance to avian viral diseases, and vaccine technologies.

Current Graduate Student Positions

Areas of Interest

  • Avian virology
  • Poultry diseases
  • Poultry pathology
  • Pathogenesis of high-consequence poultry viral diseases (Newcastle disease and avian influenza virus)
  • Mechanisms of resistance to virus infection.

Lab Profile

Detection and surveillance of significant pathogens in Ontario small poultry flocks

The University of Guelph and the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA), through the Animal Health Laboratory (AHL) and the Ontario Animal Health Network, will be conducting an infectious disease surveillance study in small (non-commercial and non-quota) poultry flocks in Ontario (click here to download a flyer advertising the study).

Rationale: The number of small poultry flocks has markedly increased over the past few years in Ontario, however, there is a void of knowledge regarding the type of diseases that affect this segment of the poultry sector.

Methods: In this project, we plan to conduct a prospective study of small poultry flock postmortem cases submitted to the Animal Health Laboratory (AHL) for two years (starting October 1st 2015), focusing on a prioritized list of infectious diseases. Upon the flock owner’s consent, in addition to a complete postmortem analysis, an extensive battery of tests will be carried out for infectious disease surveillance at a substantially discounted fee (total cost, $25). Standardized questionnaires administered to participating owners will help to understand common husbandry and biosecurity practices in these flocks.

Benefits: By conducting this prospective study we anticipate to establish a baseline for the prevalence of important viral, bacterial and parasitic diseases of Ontario small flocks. Through the information collected from standardized questionnaires completed by small flock owners, we expect to link specific management practices to prevalence of certain infectious diseases. Ultimately, this study will be used to aid in prevention, control and surveillance of relevant diseases among small flocks in Ontario. The data derived from this study will be used in extension programs to raise awareness of common poultry diseases linked to this type of production among veterinarians and small flock producers.

To participate in this study (please refer to the consent form [for detailed information about inclusion criteria and how to participate):

  1. You (the owner of the flock) and your flock must reside in Ontario.
  2. Your flock must meet the criteria of a non-commercial, non-quota flock: 49 or fewer turkeys; 99 or fewer layer chickens; 299 or fewer broiler chickens; or 300 or fewer birds for ducks, geese, and gamebirds. Pigeons and doves are excluded from this study.
  3. Submissions can only be made to the Animal Health Laboratory (AHL) through your veterinarian: contact your veterinarian about submitting samples.
  4. You must provide at the time of submission (testing will not be performed unless these items are received):
  5. The specific AHL Small Flock Project Submission Form (to be completed by you or your veterinarian);
  6. The $25 fee;
  7. The Husbandry and Biosecurity Small Poultry Flock Questionnaire (to be completed by the owner - this will take approximately 15 minutes); and
  8. A signed Consent Form (to be completed by the owner – signature page in duplicate). 
  9. You must agree to be contacted by phone or e-mail at a later time for follow-up questions or to provide clarification to the answers you provided in the questionnaire.


Click on the links to download each form (these three forms need to be completed in order for each participant to be enrolled in this study).

  1. AHL Small Flock Project Submission Form
  2. Husbandry and Biosecurity Small Poultry Flock Questionnaire
  3. Consent Form


If you have questions, please email or call (519) 824-4120:



  • VETM*4480 Comparative Medicine
  • VETM*4530 Health Management – Poultry
  • OVC Phase 4 – Anatomic Pathology Rotation


  • PABI*6080 Diagnostic Pathology I
  • PABI*6090 Diagnostic Pathology II
  • PABI*6091 Diagnostic Pathology III


Selected Publications

Susta L, Diel DG, Courtney S, Cardenas-Garcia S, Sundick RS, Miller PJ, Brown CC, Afonso CL. Expression of chicken interleukin-2 by a highly virulent strain of Newcastle disease virus leads to decreased systemic viral load but does not significantly affect mortality in chickens. Virol J. 2015 Aug 8;12:122.

Hutcheson JM*, Susta L*, Stice SL, Afonso CL, West FD. Delayed Newcastle disease virus replication using RNA interference to target the nucleoprotein. Biologicals. 2015 Jul;43(4):274-80. *(Equally contributing authors)

Cardenas-Garcia S, Diel DG, Susta L, Lucio-Decanini E, Yu Q, Brown CC, Miller PJ, Afonso CL. Development of an improved vaccine evaluation protocol to compare the efficacy of Newcastle disease vaccines. Biologicals. 2015 Mar;43(2):136-45.

Pantin-Jackwood M, Miller PJ, Spackman E, Swayne D, Susta L, Costa-Hurtado M, Suarez D. Role of poultry in spread of novel H7N9 influenza virus in China. J Virol. 2014 May;88(10):5381-90.

Susta L*, Hamal KR, Cardenas-Garcia S, Miller PJ, Brown CC, Afonso CL. Separate Evolution of Virulent Newcastle Disease Virus from Mexico and Central America. J Clin Microbiol. 2014 May;52(5):1382-90. *(Corresponding author)

Susta L*, Jones MEB, Cattoli G, Cardenas GS, Miller PJ, Afonso CL, Brown CC. Clinical and Pathologic Characterization of Genotypes XIV and XVII Newcastle disease Viruses and Efficacy of Classical Vaccination on SPF birds. Vet Pathol. 2014 Feb 7. *(Corresponding author)

Susta L, Cornax I, Diel GD, Garcia SC, Miller PJ, Liu X, Hu S, Brown CC, Afonso CL. Expression of interferon gamma by a highly virulent strain of Newcastle disease virus decreases its pathogenicity in chickens. Microb Pathog. 2013 Aug-Sep;61-62:73-83.

Batelli O, Susta L, Howerth EW. Fibrinous Pericarditis due to FIP virus. J Am Vet Med Assoc. 2014 Oct 15;245(8):899-901

Brown CC, Sullivan L, Dufour-Zavala L, Kulkarni A, Williams SM, Susta L, Zhang J, Sellers H. Presence of APMV-1 through immunohistochemistry in tracheas of experimentally and naturally infected chickens. Avian Diseases. 2013 Mar; 57(1): 36-40

Courtney SC*, Susta L*, Gomez D, Hinesc NL, Pedersen JC, Brown CC, Miller PJ, and Afonso CL. Highly Divergent Virulent Isolates of Newcastle Disease Virus from the Dominican Republic are Members of a New Genotype that May have Evolved Unnoticed for Over Two Decades. J Clin Microbiol. 2013 Feb;51(2):508-17. *(Equally contributing authors)

Rissi DR, Susta L. Leukoencephalomalacia in a horse. J Am Vet Med Assoc. 2013 Jul 1;243(1):57-9.

Courtney SC, Gomez D, Susta L, Hines N, Pedersen JC, Miller PJ, Afonso CL. Complete genome sequencing of a novel Newcastle disease virus isolate circulating in layer chickens in the Dominican Republic. J Virol. 2012 Sep; 86(17): 9550.

Susta L, Uhl EW, Grosenbaugh D, Krimer PM. Synovial lesions in experimental canine Lyme borreliosis. Vet Pathol. 2012 May; 49(3): 453-61

Diel DG, Susta L, Cardenas GS, Killian ML, Brown CC, Miller PJ, Afonso CL. Complete Genome and Clinicopathological Characterization of a Virulent Newcastle Disease Virus Isolated from Poultry in South America. J Clin Microbiol. 2012 Feb; 50(2): 378-87.

Harrison L, Brown CC, Afonso CL, Zhang J, Susta L *. Early occurrence of apoptosis in lymphoid tissues from chickens infected with strains of Newcastle disease virus of varying virulence. J Comp Pathol. 2011 Nov; 145(4): 327-35.  *(Corresponding author)

Krimer PM, Miller A, Li Q, Grosenbaugh D, Susta L, Schatzberg S. Molecular and pathological investigations of the central nervous system in Borrelia burgdorferi infected dogs. J Vet Diagn Invest. 2011 July; 23:757-763.

Cattoli G, Susta L, Calogero T, Brown CC. Newcastle Disease - Current state of field and laboratory detection. (Invited review) J Vet Diagn Invest. 2011 July; 23:637-656.

Ecco R, Brown C, Susta L, Cagle C, Cornax I, Pantin-Jackwood M, Miller PJ, Afonso CL. In vivo transcriptional cytokine responses and association with clinical and pathological outcomes in chickens infected with different Newcastle disease virus isolates using formalin-fixed paraffin-embedded samples. Vet Immunol Immunopathol. 2011 Jun 15; 141(3-4):221-9.

Rue C, Susta L, Brown CC, Kapczynski D, Suarez DL, King DJ, Miller PJ, Afonso CL. Virulent Newcastle Disease virus elicits a strong innate immune response in chickens. J Gen Virol. 2011 Apr; 92: 931-9.

Ecco R, Susta L, Afonso C, Miller JP, BrownCC. Neurological lesions in chickens experimentally infected with virulent Newcastle disease virus isolates. Avian Path. 2011 Apr; 40(2):145-52.

Susta L, Miller PJ, Afonso CL, Brown CC. Clinicopathological characterization in poultry of three strains of Newcastle Disease virus isolated from recent outbreaks. Vet Pathol. 2011 Mar; 48:349-60

Susta L, Miller PJ, Afonso CL, Estevez C, Yu Q, Zhang J, Brown CC. Pathogenicity evaluation of different Newcastle disease virus chimeras in 4-week-old chickens. Trop Anim Health Prod. 2010 Dec; 42:1785-95.

Boone AC, Susta L, Rech RR, Steffens RC, Howerth EW. Pathology in practice. Diagnosis: Poliomyelitis with intraneuronal Negri bodies. J Am Vet Med Assoc. 2010 Aug 1; 237:277-9.

Rue CA, Susta L, Brown CC, Pasick JM, Swafford SR, Wolf PC, Killian ML, Pedersen JC, Miller PJ, Afonso CL. Evolutionary changes affecting rapid identification of 2008 Newcastle disease viruses isolated from double-crested cormorants. J Clin Microbiol. 2010 Jul; 48:2440-8.

Susta L, Torres-Velez F, Zhang J, Brown CC. An in situ hybridization and immunohistochemical study of cytauxzoonosis in domestic cats. Vet Pathol. 2009 Nov; 46:1197-204.