Leonardo Susta

Leonardo Susta head shot

Assistant Professor

DVM, PhD, Diplomate ACVP
 Office: PAHL 4823
 519-824-4120 Ext. 54323

 Lab: PAHL 4811
 519-824-4120 Ext. 54640



After earning a degree of Veterinary Medicine Degree in Perugia, Italy, I completed a PhD combined residency in anatomic veterinary pathology at the University of Georgia, Athens (USA). Thereafter, I obtained certification from the American College of Veterinary Pathologists, and worked as a postdoctoral research fellow at the Southeast Poultry Research Laboratory (USDA-ARS) in Athens, Georgia. 

In 2014 I joined the faculty of the Pathobiology Department, where I developed a research program focused on infectious diseases of poultry and other avian species with particular emphasis on poultry and pet birds. My work spans from disease surveillance, development of new diagnostic methods for avian infectious diseases, and basic research involving avian viruses (such as Newcastle disease virus and aquatic bird bornavirus). My laboratory is funded by multiple agencies, including the Canadian Foundation for Innovation (CFI), the Natural Sciences and Engineering Research Council of Canada (NSERC), the Ontario Ministry of Agriculture and Rural Affairs (OMAFRA), and Pet Trust. My teaching and diagnostic expertise is comparative pathology, and at OVC I teach in the veterinary and graduate curriculum, including performing diagnostic activity (biopsy and postmortem) for the OVC Teaching Hospital and the Toronto zoo. 

This lab seeks highly motivated students who are interested in avian virology and want to investigate the basic mechanisms of viral pathogenesis through in vitro and in vivo experiments.  Applied training covers pathology of avian and exotic species, and research projects in disease surveillance and validation of new diagnostic tools. 

Current Graduate Student Positions

Research Interests

  • Avian virology

  • Diseases and diagnostic pathology of poultry 

  • Diseases and diagnostic pathology of pet birds 

  • Use of avian viruses as oncolytic agents

Lab Profile


Resistance to Newcastle disease virus (NDV) infection

  • Newcastle disease is a devastating disease of poultry globally.
  • Although vaccination against NDV can protect birds, it does not confer sterile immunity, allowing shedding and circulation of virulent strains and leading to decreased vaccine efficacy.
  • Discovery of host genes associated with resistance to NDV could lead to selection of birds that are resistant or less susceptible to Newcastle disease.

Research goals: Using lentiviral mutagenesis, develop a population of mutagenized haploid cells that can be infected with NDV to assess what mutations (loss of function) confer resistance to infection.

Pathogenesis of aquatic bird bornavirus (ABBV) in poultry

  • ABBV is a recently discovered species in the family Bornaviridae.
  • ABBV is highly prevalent in waterfowl (e.g., Canada geese, trumpeter swans) across North America, and in these birds it can cause chronic neurological disease characterized by loss of intestinal tone and chronic wasting.
  • ABBV has a wide host range, and it has been occasionally isolated from multiple species, including gulls, raptors and galliformes.
  • Give this wide host range, it is possible that ABBV may infect and cause disease in poultry species, such as chickens and turkeys. However, the potential of ABBV to infect these species is unknown. 

Research goals: To characterize host restriction of ABBV in ducks, chickens and turkeys in vitro (primary cell lines), in ovo (embryonated eggs), and adult birds by evaluating virus replication, antiviral response, lesions development, and seroconversion. 


Breast myopathies in broilers

  • Wooden Breast Syndrome (WB) and White Striation (WS) are breast myopathies of broilers. 
  • WB and WS cause myofiber loss and muscle fibrosis, leading to poor meat processability, economic losses at the processing plant, and negative customer perception.
  • The prevalence of these myopathies has increased in many countries, with WB prevalence reaching 27-32% in the US, leading to an estimate $200M losses per year. The prevalence of WB and WS in Canada is unknown.

Research goals: The goals of this project are threefold: 1) Assess the prevalence of WB and WS in Ontario, 2) Refine a histological grading scheme to evaluate the severity of WB and WS, and 3) Validate in-line diagnostic methods (e.g., impedance and ultrasound) that can be applied at the processing plant.

Surveillance of pathogens and diseases in small poultry flocks in Ontario

  • Non-quota, non-commercial poultry flocks (i.e., small flocks, also known as backyard flocks) are becoming increasingly popular within city boundaries.
  • Despite such popularity, prevalence of infectious pathogens – including zoonotic bacteria such as Campylobacter spp. and Salmonella spp. – among these flocks in Ontario is unknown. 

Research goals: To assess the prevalence of infectious agents and diseases among small flocks in Ontario, through both a prospective surveillance project and a retrospective review of post-mortem submission to the Animal Health Laboratory and the Ontario Veterinary College.


Development of multiplex PCR for detection of viruses in psittacine birds

  • Currently, at OVC there are no multiplex real-time (rt) PCR assays to detect some of the main DNA viruses affecting psittacine birds (i.e., psittacid herpesvirus-1, polyomavirus and circovirus). 

Research goals: To validate a multiplex a rtPCR assay for psittacid herpesvirus-1, polyomavirus and circovirus, through the use of a cohort of positive and negative cases derived from a review of archived tissue material (formalin-fixed, paraffin embedded tissues from post-mortem cases). 

Validation of immunohistochemical markers for round cell tumors in psittacine birds

  • Round cell tumors in psittacine birds are not well characterized, and cross reactivity with markers (antibodies) commonly used in mammalian species for diagnosis has not been systematically evaluated.  

Research goals: Using archived material from round cell tumors of psittacine birds, this project aims to validate an array of commercially available antibodies to assess cross-reactivity with psittacine birds, and to better characterize the phenotype of round cell tumors in these birds. 

Current Graduate Students

  • Fernanda Ampuero - DVSc
  • Lisa Gordon - DVSc
  • Sara Pagliarani - DVSc
  • Antonius El-Khoury - MSc



  • VETM*4480 Comparative Medicine
  • VETM*4530 Health Management – Poultry
  • OVC Phase 4 – Anatomic Pathology Rotation
  • 4th year research project - MCB*4500/4510, MCB*4521


  • PABI*6080 Diagnostic Pathology I
  • PABI*6090 Diagnostic Pathology II
  • PABI*6091 Diagnostic Pathology III
  • PABI*6050 Applied Avian Pathology I
  • PABI*6630 Applied Comparative Pathology I
  • PABI*6640 Applied Comparative Pathology II
  • PABI*6650 Applied Comparative Pathology III
  • PABI*6222 Comparative Veterinary Pathology I



Research Gate

Selected Publications


Bertran K, Susta L, Miller PJ. 2017. Avian influenza virus and Newcastle disease virus. In: Hester, P.Y., editor. Egg Inovations and Strategies for Improvements. Little Rock, AR: Oxford Academic Press. p. 547-559. doi:10.1016/B978-0-12-800879-9.00051-2.


MacDonald AM, Jardine CM, Bowman J, Susta L, Nemeth NM. DETECTION OF LYMPHOPROLIFERATIVE DISEASE VIRUS IN CANADA IN A SURVEY FOR VIRUSES IN ONTARIO WILD TURKEYS ( MELEAGRIS GALLOPAVO). J Wildl Dis. 2018 Aug 20. doi: 10.7589/2018-01-013. [Epub ahead of print] PubMed PMID: 30124393.

MacDonald AM, Jardine CM, Rejman E, Barta JR, Bowman J, Cai HY, Susta L, Nemeth NM. High Prevalence of Mycoplasma and Eimeria Species in Free-Ranging Eastern Wild Turkeys ( Meleagris gallopavo silvestris) in Ontario, CanadaJ Wildl Dis. 2018 Jun 27. 

MacDonald AM, Jardine CM, Susta L, Slavic D, Nemeth NM. Survey for Bacteria and Antimicrobial Resistance in Wild Turkeys ( Meleagris gallopavo) in Ontario, CanadaAvian Dis. 2018 Jun;62(2):184-188. 

Susta L, Segovia D, Olivier TL, Dimitrov KM, Shittu I, Marcano V, Miller PJ. Newcastle Disease Virus Infection in QuailVet Pathol. 2018 Sep;55(5):682-692. 

Santry LA, McAusland TM, Susta L, Wood GA, Major PP, Petrik JJ, Bridle BW, Wootton SK. Production and Purification of High-Titer Newcastle Disease Virus for Use in Preclinical Mouse Models of CancerMol Ther Methods Clin Dev. 2017 Oct 16;9:181-191. 

Parreira VR, Ojha S, Lepp D, Mehdizadeh Gohari I, Zhou H, Susta L, Gong J, Prescott JF. Necrotic enteritis locus 1 diguanylate cyclase and phosphodiesterase (cyclic-di-GMP) gene mutation attenuates virulence in an avian necrotic enteritis isolate of Clostridium perfringens. Vet Microbiol. 2017 Sep;208:69-73.

Mould RC, AuYeung AWK, van Vloten JP, Susta L, Mutsaers AJ, Petrik JJ, Wood GA, Wootton SK, Karimi K, Bridle BW. Enhancing Immune Responses to Cancer Vaccines Using Multi-Site Injections. Sci Rep. 2017 Aug 16;7(1):8322.

Susta L, He Y, Hutcheson JM, Lu Y, West FD, Stice SL, Yu P, Abdo Z, Afonso CL. Derivation of chicken induced pluripotent stem cells tolerant to Newcastle disease virus-induced lysis through multiple rounds of infection. Virol J. 2016 Dec 5;13(1):205.

Susta L, Dimitrov KM, Miller PJ, Brown CC, Afonso CL. Reply to "May Newly Defined Subgenotypes Va and Vb of Newcastle Disease Virus in Poultry Be Considered Two Different Genotypes?". J Clin Microbiol. 2016 Aug;54(8):2205-6.

Pandarangga P, Brown CC, Miller PJ, Haddas R, Rehmani SF, Afonso CL, Susta L.  Pathogenesis of New Strains of Newcastle Disease Virus From Israel and Pakistan. Vet Pathol. 2016 Jul;53(4):792-6.

Sá E Silva M, Susta L, Moresco K, Swayne DE. Vaccination of chickens decreased Newcastle disease virus contamination in eggs. Avian Pathol. 2016;45(1):38-45.

Moura VM, Susta L, Cardenas-Garcia S, Stanton JB, Miller PJ, Afonso CL, Brown  CC. Neuropathogenic Capacity of Lentogenic, Mesogenic, and Velogenic Newcastle Disease Virus Strains in Day-Old Chickens. Vet Pathol. 2016 Jan;53(1):53-64.

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 chickensVirol 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 nucleoproteinBiologicals. 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 vaccinesBiologicals. 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 ChinaJ 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 AmericaJ 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 birdsVet 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 chickensMicrob 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 DecadesJ Clin Microbiol. 2013 Feb;51(2):508-17. *(Equally contributing authors)

Rissi DR, Susta LLeukoencephalomalacia 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 CCNewcastle 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 samplesVet 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 CLVirulent 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, BrownCCNeurological 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 chickensTrop 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.

Search PubMed for additional publications by Dr. Susta.