Dr Andrea McWhorter
Grant-Funded Researcher (A)
School of Animal and Veterinary Science
Faculty of Sciences, Engineering and Technology
Eligible to supervise Masters and PhD - email supervisor to discuss availability.
In 2012, I started a post-doctoral fellowship studying the comparative virulence of Salmonella serovars. Salmonella is a diverse bacterial genus with well over 2600 distinct serovars having been described. In our work, we have found that Salmonella serovars have significant variation in their in vitro and in vivo virulence capacities. This work has been published in both Frontiers in Microbiology and Applied and Environmental Microbiology. We have analysed whole genome sequences of selected Salmonella serovars and compared the variation that occurs amongst genes controlling bacterial invasion, intracellular replication and other disease processes. We have found substantial variation in the amino acid sequences between the selected serovars and are now in the process of characterising how this amino acid variability translates to functional variability.
I recently completed an epidemiology project tracking where Salmonella enters the egg laying production system. Egg laying hens typically become infected with Salmonella when they are transferred from rearing farms to production facilities at 15-18 weeks of age (McWhorter and Chousalkar, unpublished). Infection with Salmonella at this point typically does not cause disease symptoms in the birds because the dose is generally low and chickens, in general, are more resistance to non-species specific Salmonella than other vertebrates. My work has shown that the bacteria establish persistent infection and can be shed intermittently over the 80 week production lifespan of a layer hen. This leads to increased contamination of the farm environment and can then be a risk for egg contamination.
On farm Salmonella control programs are multifaceted involving strict biosecurity, cleaning and disinfecting. The use of a live, attenuated strain of Salmonella Typhimurium as a vaccine has been adopted in certain parts of the poultry industry. The vaccine has been shown to have efficacy in chicken meat birds but because of the extended productive lifespan of a layer hen, it was not known how effective the vaccine is over an extended period. We conducted both controlled experimental and on farm trials which demonstrated that the vaccine was not able to prevent infection or reduce the total amount of Salmonella shed in faeces or the rate of egg contamination. This outcome has led the further collaboration with the vaccine manufacturer, Bioproperties.
Most recently, I have commenced a project testing the efficacy of several commercial sanitizers used in the chicken meat industry to control Campylobacter and Salmonella. I am also working on studying the behaviour of Salmonella in raw egg-based foods. In artificially contaminated aioli, the number of culturable bacteria decreases over time. I established, however, that while the bacteria were non-culturable, they remained viable (viable-but-nonculturable, VBNC). This part of my research program is now aimed at understanding the risk that VBNC Salmonella in food represents for human disease.
Date Position Institution name 2013 - ongoing Associate Lecturer University of Adelaide 2012 - ongoing Post-doctoral Research Fellow University of Adelaide
Date Institution name Country Title 2011 University of Western Australia Australia PhD 1998 University of Wyoming United States Masters of Science
Year Citation 2023 Jia, S., McWhorter, A. R., Khan, S., Andrews, D. M., Underwood, G. J., & Chousalkar, K. K. (2023). Investigation of a gel-based delivery method for the administration of a live, attenuated Salmonella Typhimurium vaccine.. Veterinary microbiology, 280, 109721.
2022 Weerasooriya, G., Khan, S., Chousalkar, K. K., & McWhorter, A. R. (2022). Invasive potential of sub-lethally injured Campylobacter jejuni and Salmonella Typhimurium during storage in chicken meat juice. Food Control, 135, 108823-1-108823-13.
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2022 McWhorter, A. R., Weerasooriya, G., Willson, N. L., & Chousalkar, K. K. (2022). Peroxyacetic acid and acidified sodium chlorite reduce microbial contamination on whole chicken carcasses obtained from two processing points. Food Microbiology, 106, 12 pages.
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2022 Weerasooriya, G., McWhorter, A. R., Khan, S., & Chousalkar, K. K. (2022). Effects of Sublethally Injured Campylobacter jejuni in Mice. Microbiology Spectrum, 10(4), 16 pages.
2021 McWhorter, A. R., Khan, S., Sexton, M., Moyle, T. S., & Chousalkar, K. K. (2021). Acidification and extended storage at room temperature of mayonnaise reduce Salmonella Typhimurium virulence and viability. Food Research International, 141, 110117-1-110117-9.
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2021 Lin, Q., Chousalkar, K. K., McWhorter, A. R., & Khan, S. (2021). Salmonella Hessarek: An emerging food borne pathogen and its role in egg safety. Food Control, 125, 107996-1-107996-10.
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2021 McWhorter, A., Owens, J., Valcanis, M., Olds, L., Myers, C., Smith, I., . . . McLelland, D. (2021). In vitro invasiveness and antimicrobial resistance of Salmonella enterica subspecies isolated from wild and captive reptiles. Zoonoses and Public Health, 68(5), 402-412.
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2021 Weerasooriya, G., McWhorter, A. R., Khan, S., & Chousalkar, K. K. (2021). Transcriptomic response of Campylobacter jejuni following exposure to acidified sodium chlorite.. NPJ science of food, 5(1), 9 pages.
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2021 Khan, S., McWhorter, A. R., Moyle, T. S., & Chousalkar, K. K. (2021). Refrigeration of eggs influences the virulence of Salmonella Typhimurium.. Sci Rep, 11(1), 1-12.
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2020 Jia, S., McWhorter, A. R., Andrews, D. M., Underwood, G. J., & Chousalkar, K. K. (2020). Challenges in vaccinating layer hens against salmonella typhimurium. Vaccines, 8(4), 696.
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2020 McWhorter, A. R., & Chousalkar, K. K. (2020). Salmonella on Australian cage egg farms: Observations from hatching to end of lay. Food Microbiology, 87, 12 pages.
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2020 Kuriyawe Muhandiramlage, S., McWhorter, A. R., & Chousalkar, K. K. (2020). Chlorine Induces Physiological and Morphological Changes on Chicken Meat Campylobacter Isolates.. Front Microbiol, 11, 503.
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2020 McWhorter, A. R., Sexton, M., & Chousalkar, K. K. (2020). The effects of varied food acid ratios and egg components on Salmonella Typhimurium culturability from raw egg-based sauces. Food Microbiology, 92, 7 pages.
2020 Chousalkar, K. K., Khan, S., & McWhorter, A. R. (2020). Microbial quality, safety and storage of eggs. Current Opinion in Food Science, 38, 91-95.
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2019 McWhorter, A. R., & Chousalkar, K. K. (2019). From hatch to egg grading: monitoring of Salmonella shedding in free-range egg production systems. Veterinary Research, 50(1), 58.
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2019 McWhorter, A. R., Tearle, R., Moyle, T. S., & Chousalkar, K. K. (2019). In vivo passage of Salmonella Typhimurium results in minor mutations in the bacterial genome and increases in vitro invasiveness.. Vet Res, 50(1), 1-10.
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2019 Chousalkar, K., Sims, S., McWhorter, A., Khan, S., & Sexton, M. (2019). The Effect of Sanitizers on Microbial Levels of Chicken Meat Collected from Commercial Processing Plants.. International journal of environmental research and public health, 16(23), 11 pages.
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2018 Pande, V., McWhorter, A., & Chousalkar, K. (2018). Anti-bacterial and anti-biofilm activity of commercial organic acid products against Salmonella enterica isolates recovered from an egg farm environment. Avian Pathology, 47(2), 189-196.
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2018 McWhorter, A., Phan, G., Hocking, H., & Chousalkar, K. (2018). In vitro invasion capacity of Salmonella Typhimurium DT9 isolates sourced from humans and layer hen environments. Zoonoses and Public Health, 65(1), e259-e264.
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2018 Howard, A. J., Chousalkar, K. K., & McWhorter, A. R. (2018). In vitro and in vivo efficacy of a live attenuated Salmonella Typhimurium vaccine at preventing intestinal colonization in chicks. Zoonoses and public health, 65(6), 736-741.
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2018 McWhorter, A., & Chousalkar, K. (2018). A long-term efficacy trial of a live, attenuated Salmonella Typhimurium vaccine in layer hens. Frontiers in Microbiology, 9(JUN), 1380-1-1380-13.
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2018 Sharma, P., Caraguel, C., Sexton, M., McWhorter, A., Underwood, G., Holden, K., & Chousalkar, K. (2018). Shedding of Salmonella Typhimurium in vaccinated and unvaccinated hens during early lay in field conditions: A randomised controlled trial. BMC Microbiology, 18(1), 9 pages.
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2017 Sharma, P., Pande, V., Moyle, T., McWhorter, A., & Chousalkar, K. (2017). Correlating bacterial shedding with fecal corticosterone levels and serological responses from layer hens experimentally infected with Salmonella Typhimurium. Veterinary Research, 48(1), 5-1-5-11.
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2017 Chousalkar, K., Sexton, M., McWhorter, A., Hewson, K., Martin, G., Shadbolt, C., & Goldsmith, P. (2017). Salmonella Typhimurium in the Australian egg industry: multidisciplinary approach to addressing the public health challenge and future directions. Critical Reviews in Food Science and Nutrition, 57(12), 2706-2711.
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2016 Pande, V., Devon, R., Sharma, P., McWhorter, A., & Chousalkar, K. (2016). Study of Salmonella typhimurium infection in laying hens. Frontiers in Microbiology, 7(FEB), 10 pages.
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2016 Pande, V., McWhorter, A., & Chousalkar, K. (2016). Salmonella enterica isolates from layer farm environments are able to form biofilm on eggshell surfaces. Biofouling, 32(7), 699-710.
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2016 McWhorter, A., & Chousalkar, K. (2016). In vitro invasive capacity of Salmonella strains into sections of the layer hen oviduct. Veterinary Microbiology, 192, 135-144.
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2015 McWhorter, A., Davos, D., & Chousalkar, K. (2015). Pathogenicity of Salmonella strains isolated from egg shells and the layer farm environment in Australia. Applied and Environmental Microbiology, 81(1), 405-414.
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2015 McWhorter, A., Smith, L., Shellam, G., & Redwood, A. (2015). Murine cytomegalovirus strains co-replicate at multiple tissue sites and establish co-persistence in salivary glands in the absence of Ly49H-mediated competition. Journal of General Virology, 96(5), 1127-1137.
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2015 McWhorter, A., & Chousalkar, K. (2015). Comparative phenotypic and genotypic virulence of Salmonella strains isolated from Australian layer farms. Frontiers in Microbiology, 6(Jan), 12-1-12-14.
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2015 Hemmatzadeh, F., Keyvanfar, H., Hasan, N., Niap, F., Bani Hassan, E., Hematzade, A., . . . Ignjatovic, J. (2015). Interaction between Bovine leukemia virus (BLV) infection and age on telomerase misregulation. Veterinary Research Communications, 39(2), 97-103.
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2015 Pande, V., Gole, V., McWhorter, A., Abraham, S., & Chousalkar, K. (2015). Antimicrobial resistance of non-typhoidal Salmonella isolates from egg layer flocks and egg shells. International Journal of Food Microbiology, 203, 23-26.
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2014 Hadifar, F., Ignjatovic, J., Tarigan, S., Indriani, R., Ebrahimie, E., Haliza Hasan, N., . . . Hemmatzadeh, F. (2014). Multimeric recombinant M2e protein-based ELISA: A significant improvement in differentiating avian influenza infected chickens from vaccinated ones. PLoS One, 9(10), e108420-1-e108420-8.
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2013 McWhorter, A., Smith, L., Masters, L., Chan, B., Shellam, G., & Redwood, A. (2013). Natural killer cell dependent within-host competition arises during multiple MCMV infection: consequences for viral transmission and evolution. PLoS Pathogens, 9(1), e1003111-1-e1003111-13.
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2013 Smith, L., McWhorter, A., Shellam, G., & Redwood, A. (2013). The genome of murine cytomegalovirus is shaped by purifying selection and extensive recombination. Virology, 435(2), 258-268.
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2009 Beauvais, D., Ell, B., McWhorter, A., & Rapraeger, A. (2009). Syndecan-1 regulates αvβ₃ and αvβ₅ integrin activation during angiogenesis and is blocked by synstatin, a novel peptide inhibitor. Journal of Experimental Medicine, 206(3), 691-705.
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2008 Gorman, S., Lloyd, M., Smith, L., McWhorter, A., Lawson, M., Redwood, A., & Shellam, G. (2008). Prior infection with murine cytomegalovirus (MCMV) limits the immunocontraceptive effects of an MCMV vector expressing the mouse zona-pellucida-3 protein. Vaccine, 26(31), 3860-3869.
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2008 Smith, L., McWhorter, A., Masters, L., Shellam, G., & Redwood, A. (2008). Laboratory strains of murine cytomegalovirus are genetically similar to but phenotypically distinct from wild strains of virus. Journal of Virology, 82(13), 6689-6696.
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2004 Simon, A. M., McWhorter, A. R., Chen, H. D. R., Jackson, C. L., & Ouellette, Y. (2004). Decreased intercellular communication and connexin expression in mouse aortic endothelium during lipopolysaccharide-induced inflammation. Journal of Vascular Research, 41(4), 323-333.
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2004 Simon, A. M., McWhorter, A. R., Dones, J. A., Jackson, C. L., & Chen, H. D. R. (2004). Heart and head defects in mice lacking pairs of connexins. Developmental Biology, 265(2), 369-383.
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2004 Simon, A. M., McWhorter, A. R., Dones, J. A., Jackson, C. L., & Chen, H. D. R. (2004). Erratum: Heart and head defects in mice lacking pairs of connexins (Developmental Biology (2004) 265 (369-383) DOI: 10.1016/j.ydbio.2003.09.036). Developmental Biology, 271(2), 517-518.
2003 Simon, A. M., & McWhorter, A. R. (2003). Role of connexin37 and connexin40 in vascular development. Cell Communication and Adhesion, 10(4-6), 379-385.
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2003 Simon, A. M., & McWhorter, A. R. (2003). Decreased intercellular dye-transfer and downregulation of non-ablated connexins in aortic endothelium deficient in connexin37 or connexin40. Journal of Cell Science, 116(11), 2223-2236.
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2002 Simon, A. M., & McWhorter, A. R. (2002). Vascular abnormalities in mice lacking the endothelial gap junction proteins connexin37 and connexin40. Developmental Biology, 251(2), 206-220.
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2000 Simon, A. M., McWhorter, A. R., Sellitto, C., Goodenough, D. A., & Paul, D. L. (2000). Generation of vascular connexin double knockout mice.. FASEB JOURNAL, 14(4), A541. 2000 Simon, A. M., & McWhorter, A. R. (2000). Developmental defects in Cx40-/-Cx43-/- mice. MOLECULAR BIOLOGY OF THE CELL, 11, 227A.
Year Citation 2017 Chousalkar, K., & McWhorter, A. (2017). Egg Production Systems and Salmonella in Australia. In S. Ricke, & R. Gast (Eds.), Producing Safe Eggs: Microbial Ecology of Salmonella (pp. 71-85). United Kingdom: Academic Press.
Year Citation 2019 Khan, S., Chousalkar, K., & McWhorter, A. (2019). Salmonella interventions and their limitations. In Australian Veterinary Poultry Association Scientific Meeting. Sydney. 2006 Beauvais, D. M., McWhorter, A. R., Ell, B. J., & Rapraeger, A. C. (2006). Syndecan-1 regulates beta 3 and beta 5 integrin tumor-promoting activity. In MATRIX BIOLOGY Vol. 25 (pp. S42). Nashville, TN: ELSEVIER SCIENCE BV.
2003 Ouellette, Y., McWhorter, A. R., & Simon, A. M. (2003). Decreased intercellular communication and connexin 40 expression in mouse aortic endothelium during lipopolysaccharide-induced inflammation. In CRITICAL CARE MEDICINE Vol. 31 (pp. A42). ORLANDO, FLORIDA: LIPPINCOTT WILLIAMS & WILKINS.
- 2020 CIB on ARC-Linkage Grant in Collaboration with Bioproperties, "Salmonella in poultry: improving vaccine efficacy and understanding of host-pathogen interactions"
- 2020 Co-investigator on Urgent COVID-19 Research Funding Scheme, "Are Poultry Workers Our 21st Century’s Milkmaids? Chicken coronavirus vaccine: Efficacy against SARS-CoV-2 (COVID-19)"
- 2019 Co-investigator on Agrifutures Poultry Meat Scheme, "Sanitisers for commercial use in chicken meat production"
- 2016 Co-investigator on Poultry CRC grant, "Field trial to study the efficacy of a Salmonella Typhimurium live vaccine in egg layers"
- 2014 Co-investigator on Australian Eggs Grant, "Workshops for future development of Salmonella control strategies in egg industry"
Current Higher Degree by Research Supervision (University of Adelaide)
Date Role Research Topic Program Degree Type Student Load Student Name 2023 Principal Supervisor Epidemiology of avian Hepatitis E in layer hens Doctor of Philosophy Doctorate Full Time Mrs Stephanie Jane Hewitt 2023 Principal Supervisor Mechanisms of Salmonella survival on eggs and in raw egg-based foods. Doctor of Philosophy Doctorate Full Time Ms Lingyun Li 2022 Co-Supervisor Study of gut microbiota in hens Doctor of Philosophy Doctorate Full Time Mr Jiawei Zhang 2020 Co-Supervisor iPhD with Bioproperties Pty Ltd: Improving the efficacy of Salmonella Typhimurium vaccination Doctor of Philosophy Doctorate Full Time Mr Siyuan Jia
Past Higher Degree by Research Supervision (University of Adelaide)
Date Role Research Topic Program Degree Type Student Load Student Name 2019 - 2022 Co-Supervisor Study of Foodborne Pathogens in Poultry Doctor of Philosophy Doctorate Full Time Dr Gayani Kuriyawe Muhandiramlage 2019 - 2020 Co-Supervisor A study of non-typhoidal Salmonella virulence Master of Philosophy Master Full Time Miss Talia Sheryli Moyle 2014 - 2018 Co-Supervisor Study of Salmonella Typhimurium Infection in Laying Hens and Vaccination Doctor of Philosophy Doctorate Full Time Dr Pardeep Sharma 2013 - 2016 Co-Supervisor Studies on Salmonella enterica spp Isolated from Egg Farm Environment Doctor of Philosophy Doctorate Full Time Mr Vivek Pande
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