Under the microscope with ACAHF grant recipient - Mark Westman

01 Jul 2017

Mark Westman graduated with BVSC (Hons) from Sydney University in 2003 and became a member of the college of Veterinary Scientists in the Animal Welfare chapter in 2008.

Since graduation, he has mainly worked in companion animal shelters, including RSPCA NSW and Animal Welfare League NSW. He has also volunteered on many international veterinary programs and has travelled to Thailand, Indonesia, India and Papua New Guinea to help animals in vulnerable communities.

Mark’s background in shelter medicine led him to develop a keen interest in feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) which are concerning causes of feline morbidity and mortality in Australia and overseas.

He began his PhD at the University of Sydney in 2012, under the skilful supervision of A/Prof Jacqui Norris, Prof Richard Malik and A/Prof Paul Sheehy.

Around the same time, he also co-founded Pets in the Park, a charity dedicated to providing free veterinary care to pets owned by the homeless, which now has clinics in New South Wales, Victoria, Queensland and the ACT.

While working on his PhD, Mark produced six primary author papers, presented his findings at 11 veterinary conferences, and was awarded multiple scholarships and prizes (most notably a PhD Excellence Award for making a significant contribution to the field).

In 2016, Mark was awarded his PhD from Sydney University and moved to the Centre for Virus Research, University of Glasgow to pursue further research into FIV and FeLV as a postdoctoral fellow supported by an Australian Government Endeavour Research Fellowship.

Between 2013 and 2016, the ACAHF awarded Mark’s research group at the University of Sydney four separate research grants.

For this edition of Companion magazine, we asked Mark to tell us a little about how these ACAHF grants have helped him (and the other shining stars in his research group) to improve diagnostic testing practices for FIV and FeLV in cats; to help vets better understand the progressive and regressive FeLV infections that harm our feline friends; and to advance vets’ understanding of the antibody response that occurs in cats following an FIV-vaccination.

Diagnosing FIV and FELV

We received our first ACAHF grant in 2013. It was based on the diagnosis of FIV and FeLV using three different commercially available test kits, using both blood and saliva.

I vividly remember the moment when I found out our application had been successful. I had been a full-time clinical veterinarian for eight years before starting my PhD and I had no prior research experience. I definitely experienced (and still do experience) some imposter syndrome feelings at times. I knew I was on a steep learning curve from the start, and I often wondered if I had the necessary skills or temperament to be a good researcher and complete a PhD.

Fortunately, my PhD supervisors were Richard Malik and Jacqui Norris. Richard is one of the most respected and well-known feline veterinarians in the world and Jacqui is an amazing researcher and teacher too. Last year Jacqui won the Supervisor of the Year award for the Faculty of Veterinary Science and that’s just one of her many accolades.

I have no doubt that it was mainly the strength of their track record in successfully completing ACAHF grant projects in the past that helped us over the line with our application. But as the primary investigator named on the ACAHF application, it was still a huge boost to my confidence that a panel of external adjudicators considered my research project as worthy of financial support. I remember jubilantly celebrating with Richard and Jacqui – and then getting straight back to work!

We recruited our cat ‘volunteers’ for the study from twelve veterinary clinics located across four states of Australia. They were all pet cats visiting veterinary clinics, mainly for routine procedures (e.g. dentals, vaccinations, annual health checks).

It was a joy to work with so many lovely veterinarians and veterinary nurses and to meet the wonderful owners of these cats. They were all enthusiastic about contributing to our research and it was a really enjoyable experience. I always looked forward to my ‘sampling days’ at the vet clinics.

I worked on this project full-time for three years and the research we did allowed us to make the breakthrough discovery that two of the three test kits could diagnose FIV in FIV-vaccinated cats – something that was previously thought impossible using commercial antibody testing.

Prior to our work, results from the testing of FIV-vaccinated cats using only one commercially available FIV antibody kit had been published. This kit, which is available worldwide and was also tested in our study, is unable to differentiate between FIV-vaccinated and FIV-infected cats. It was presumed, based on the results of testing with this kit, that all kits would be the same. It was this extrapolation (i.e. from the results of this one kit to all kits) that we discovered was incorrect.

This was hugely exciting for us because the publication of our results in 2015 really changed the conventional thinking on bestpractice diagnostic techniques for identifying this virus in FIV-vaccinated cats. Our paper was cited in the 2016 WSAVA Vaccination Guidelines and our study has since been replicated overseas (in Florida, USA).

It’s difficult to overstate the impact our finding has had on both clinical practice and shelters in Australia. Most (if not all) major shelters in Australia who routinely screen on intake for FIV and FeLV have now changed their choice of test kit following the release of our results, potentially saving thousands of cats from unnecessary euthanasia due to inaccurate FIV test results.

Our discovery that saliva can be used, instead of blood, to diagnose FIV and FeLV using two of the three kits was also a relatively novel diagnostic approach (piggybacking on some great preliminary work out of Townsville by A/Prof Richard Squire’s group) and we found it was particularly useful for dealing with fractious cats. So that was another happy outcome – as we all know how stressed-out and uncooperative some cats can get when they visit the vet!

As part of this research, we also investigated the high number of false positive test results that can occur with in-house FeLV testing, and the resulting need for vets to be routinely performing confirmatory PCR testing to avoid unnecessary euthanasia due to inaccurate test results.

We’re not suggesting that in-house FeLV test kits are inherently faulty. But our results are a reminder that with any diagnostic testing for a disease with low population prevalence (such as FeLV), false positive test results will occur more commonly (i.e. as disease incidence decreases, so the positive predictive value of a diagnostic test decreases.)

Ideally, all in-house FeLV positive test results should be followed by confirmatory testing, ideally PCR testing, or if this is unavailable at least testing with a second (and different) in-house FeLV kit.

Progressive and regressive FELV infections in Australian cats and the anti-viral treatment for FELV-infected cats (raltegravir)

After the success of our first project, we were naturally very keen to continue our work into the diagnosis of feline retroviruses. We submitted two further grant applications and in 2014 and 2015, we received our second and third ACAHF research grants to study the prevalence of both progressive and regressive FeLV infections in Australian cats. We also secured the necessary funding to investigate an innovative anti-viral treatment for FeLV-infected cats (raltegravir).

These new ACAHF grants allowed us to test 440 samples that we had left over from our FIV vaccine-effectiveness study. We were also put in contact with a rescue facility experiencing a FeLV outbreak by feline specialist Dr Andrea Harvey at the Small Animal Specialist Hospital, Sydney. She had treated a cat from the same facility with feline sarcoma virus infection (which is a mutation of FeLV).

Using three different in-house FeLV kits, the FeLV PCR assay we developed during my PhD at the University of Sydney, and the samples we had collected from our FIV vaccine effectiveness study, we found regressive infections were four times more common in the general population of Australian cats compared to progressive infections (2% vs 0.5%), suggesting Australian cats with outdoor access are at higher risk of FeLV exposure than previously thought.

We tested every in-contact cat at this facility using both in-house FeLV kits and FeLV PCR testing, and by doing so identified a group of healthy cats with progressive FeLV infections that the carers were keen to treat.

We then organised to have compounded a human anti-retroviral drug called raltegravir (that had previously been trialled in Europe in FeLV-infected cats). Testing of these cats is still in progress, and we hope to publish our results soon showing the effect of raltegravir on FeLV load over time. The early results and safety data we have analysed so far have been encouraging.

One of the challenges we’ve faced with this study is recruiting appropriate FeLV-infected cats for raltegravir treatment. Progressive FeLV infection in Australian cats is relatively rare and in addition to finding FeLV-infected cats, we also need to find cats amenable to twice daily tableting, monthly check ups, regular venepuncture, and owners able to afford the medication.

Veterinarians can greatly assist us with this since the raltegravir project is ongoing. So, if you’re a vet treating any FeLV-infected cats with owners who might be interested in being involved in our study (and preferably living in Sydney), please contact Jacqui or me!

We hope that our findings may change the approach to FeLV vaccination in at-risk cats in Australia. We’re also following on from our pilot study into the investigation of raltegavir for the treatment of FeLV-infection with a larger study in 2017-2018. And we’ve applied for another ACAHF grant to help us do this work. Fingers crossed.

Understanding the antibody response that occurs following FIV-vaccination

In 2016, we were awarded our fourth and most recent ACAHF grant. This funding allowed me to move to Scotland to pursue a postdoctorate goal with the prestigious Centre for Virus Research at the University of Glasgow (where FeLV was discovered in 1964).

The Centre for Virus Research at the University of Glasgow is a fantastic place to learn new skills and develop as a young scientist and I was absolutely thrilled to be given this opportunity.

I moved to Scotland in November 2016 and worked as a post-doctoral fellow until the end of June this year. While I was there, I expanded work from my PhD including investigation of antibodies to FeLV envelope glycoprotein (gp70) in Australian cats with outdoor access and evaluation of the FIV neutralising antibody response in Australian cats following FIV vaccination.

The aim of my work was to better understand the antibody response that occurs following FIV-vaccination the antibody response that occurs in some cats that produces protection from challenge with a wide range of FIV subtypes.

We used residual samples from our FIV vaccine-effectiveness study for this new research project, and before I left for Scotland, recruited 16 kittens and cats from two veterinary clinics and two animal shelters in Sydney to study.

Again, this shows the vital contribution that private and shelter veterinarians can make to research!

What we have discovered from my PhD and post-doctoral research is that the antibody response following FIV vaccination is perhaps more complex than previously appreciated.

Firstly, cats produce antibodies to various parts of FIV, including matrix protein (p15), capsid protein (p24) and envelope glycoprotein (gp40). Although much more work needs to be done, it appears that the strength and duration of antibody response to each component is variable and this impacts FIV diagnosis in FIV-vaccinated cats by antibody testing.

Because of this finding, we reported that Anigen Rapid (BioNote) and Witness (Zoetis) FIV kits should be used for FIV screening if there is a history of FIV vaccination, or if FIV vaccination history is unknown (e.g. in situations where cats have come from shelters and pounds).

In a follow-up study, we found that some care needs to be taken using Anigen Rapid and Witness FIV kits if primary FIV vaccination has occurred recently (< 6 months). A positive FIV result in cats recently FIVvaccinated should be confirmed by FIV PCR testing. Clinically, this does not affect most cats, as the most common time for FIV testing in FIV-vaccinated cats is prior to annual FIV vaccination to check for breakthrough FIV infection (i.e. 12 months after the last FIV vaccination). However, the occurrence of false positive FIV results following annual FIV vaccination still needs to be carefully ascertained (since cats in our 2015 study were only sampled once and at variable time points following annual FIV vaccination) and we would really love to conduct a project into this in 2018!

In the third and final part of my research in Scotland, I tested FIV-vaccinated cats against various FIV pseudotypes (viruses) from Australian breakthrough cats. Preliminary results from this study suggest that FIV vaccination induces a strong neutralising antibody response against FIV strains similar to one of the strains included in the inactivated whole vaccine, but not against genetically different FIV strains.

This finding does not necessarily mean that FIV vaccination does not produce broad protection against FIV challenge but rather, if broad protection is provided by the FIV vaccine, it is due to stimulation of cellmediated immunity rather than an effective humoral immune response.

I hope this understanding may contribute to the development of a more efficacious FIV vaccine in the future, and perhaps may also assist researchers attempting to develop a vaccine against HIV.

This was my first post-doctoral position and my first permanent stint overseas. I absolutely LOVED Scotland and och! I was very sad to leave. The retroviral research community is truly international, and these international collaborations are essential to advancing our knowledge of feline retrovirology, immunology and vaccinology.

Fortunately, and partly thanks to ACAHF funding, I had my University of Sydney research team and some exciting new projects to get straight back into when I returned home to Australia.

Everyone in our research team at the University of Sydney is very proud of our significant contribution to the study of feline retrovirology over the past five years, and we are incredibly grateful to the ACAHF for helping us with this important work!

Dr Mark Westman
Postgraduate Student
Sydney School of Veterinary Science
University of Sydney

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