1. Brucella canis: Fatty acid variability as a potential indicator of strain origin and biologic behavior
Alexandra Brower, DVM, DACVP
Clinical Associate Professor of Diagnostic Pathology
University of Wisconsin School of Veterinary Medicine

2. Canine Brucellosis Relatively new bacterial disease of dogs -
B. canis was first discovered in 1966.
The major symptoms of infection in dogs are
abortion and infertility.
Canine infections are through contact with placental fluids and aborted tissues.
Other mechanisms of transmission:
mating (venereal infections)
contact with urine
Risk as a zoonosis is considered low

3. Where are we likely to find B. canis in the US?
“Dozens and dozens of farms have signs up advertising “puppies for sale” or have placed ads in the area papers listing many different breeds at the same address. Many of them say, “No Sunday Sales” which is a good bet the seller is Amish or Mennonite. I think it’s just such a shame that Clark County has become the hotbed for puppy mills in Wisconsin so quickly and it is expanding so rapidly. What a black eye for us. How humiliating and sad.”
Clark county humane society, article titled
A dog auction experience

4. Where else do outbreaks occur?
May 6, A Puppy Farm in Ireland at Centre of Canine Brucellosis Outbreak: Has 700 breeding bitches and there are currently up to 300 puppies on the premises. K9 Magazine News Editor
What about human infections? Argentina and Mexico – Multiple published and soon to be published case reports and serologic data on human infection . N. Lucero et al Brucellosis Laboratory, Buenos Aires, Argentina

5. Diagnostic pathology interface
Veterinary diagnostic laboratories receive aborted fetuses, other tissues and blood samples from kennel outbreaks of canine brucellosis.
In Wisconsin, by late 2005 submission of samples and positive tests was clearly on the rise. Follow up with kennel owners and veterinarians led to recognition of the following important issues regarding B. canis:

6. B. canis is a common, unregulated, potentially zoonotic disease in commercial and private canine breeding facilities in Wisconsin.
Wisconsin outbreaks are due to trade practices that link kennels throughout the country.
There is an under appreciation of the disease among dog breeders, veterinarians, and diagnostic and government agencies.

7. Outbreaks from and total number of dogs in each kennel A – 10 B – 1,000 C – D – E – F – G – 2 H – I – J – G C B E
A, H, I, J D F

8. Discrimination of B. canis isolates
Identify a way to trace B. canis outbreaks.
Initial investigations used samples from three canine brucellosis outbreaks in Wisconsin dog kennels, and B. canis isolates from Missouri and Arkansas.
Brucella species have minimal genetic diversity…

9. Molecular techniques unable to discriminate isolates include: Ribotyping with multiple restriction endonucleases, outer membrane protein analysis and pulsed-field gel electrophoresis (PFGE) *Gas chromatography was found to be a technique that could discriminate between isolates.

10. Dendrogram analysis of fatty acid profiles
Dendrogram analysis of fatty acid profiles. Two major groups were found, described as southern and northern strains.
Brower et al. Investigation of the Spread of Brucella canis via the U.S. Interstate Dog Trade. International Journal of Infectious Diseases, Volume 11, Issue 5, Pages

11. Next question, why are human case reports coming from Argentina, when we have so much exposure in the US?
Compared lipid profiles of 1 human B. canis isolate, and 6 canine isolates from Argentina with 36 canine isolates from 8 other countries including the US.

12. Review of the profiles showed that only the Argentinean and Mexican isolates had19:O cyclopropane (lactobacillic acid), cis-11,12-methylene octadecanoic acid.

13. Retention time
(minutes)
Fatty acid
Percent of total fatty acids in sample
2.871
16:0
10.16
3.190
17:0
0.38
3.458
18:1 w7c
82.10
3.505
18:0
2.02
Features of a typical U.S. B. canis isolate profile and corresponding chromatograph (Isolate 19-50).

14. Retention time
(minutes) in
Fatty acid
Percent of total fatty acids in sample
2.870
16:0
11.42
3.189
17:0
0.51
3.457
18:1 w7c
39.44
3.505
18:0
5.20
3.530
11 methyl 18:1 w7c
1.02
3.793
19:0 CYCLO w8c
37.50
4.035
20:2 w6,9c
.78
Features of a typical B. canis isolate profile from Argentina and corresponding chromatograph (Isolate 5-46).

15. Brucella melitensis, suis and abortus index profile.
Reference index number
Fatty acid
Percent of total fatty acids 63
16:0
13.00 82
17:0
0.67 92
18:1 w7c
19.69 95
18:0
9.04 96
11 methyl 18:1 w7c
2.17
105
19:0 CYCLO w8c
50.23
113
20:2 w6,9c
3.17
Brucella melitensis, suis and abortus index profile.
This index includes the species of Brucella classically considered to be pathogenic to humans.

16. Argentina Isolate US Isolate Index profile Fatty acid
Percent of total fatty acids in sample
16:0
11.42
17:0
0.51
18:1 w7c
39.44
18:0
5.20
11 methyl 18:1 w7c
1.02
19:0 CYCLO w8c
37.50
20:2 w6,9c
.78
Fatty acid
Percent of total fatty acids
16:0
13.00
17:0
0.67
18:1 w7c
19.69
18:0
9.04
11 methyl 18:1 w7c
2.17
19:0 CYCLO w8c
50.23
20:2 w6,9c
3.17
Argentina Isolate
Fatty acid
Percent of total fatty acids in sample
16:0
10.16
17:0
0.38
18:1 w7c
82.10
18:0
2.02
US Isolate
Index profile

17. Dendrogram of 44 B. canis isolates

18. Brucella species lack most functional gene sequences encoding virulence – a critical component of virulence is likely the LPS surface antigen.
Sanchez et al Gene Discovery through Genomic Sequencing of Brucella abortus. Infect. Immun. 69:
Heterogeneity of the Lipid A domain of Brucella LPS may primarily depend on fatty acid substitutions
Gomes Cardoso et al Review: Brucella spp noncanonical LPS: structure, biosynthesis and interaction with host immune system. Microbial Cell Factories 5: [Online.]
Might the fatty acid difference found in the Argentinean and Mexican isolates be related to increased virulence in humans?

19. UK – Comparative study between the lipid profiling technique used by our laboratory, and a variable tandem repeat sequencing technique that the Whatmore laboratory uses to discriminate Brucella isolates.
University of Iowa – Seroepidemiologic study of B. canis that focuses on the human populations in the U.S. that are most likely to be exposed to the bacterium.

20. I am grateful to the following people for
their wonderful collaboration on this and
other Brucella canis projects.
Dr. Ogi Okwumabua, University of Wisconsin
Dr. Nidia Lucero, ANILIS Argentina
Dr. Adrian Whatmore, VLA United Kingdom
Dr. Chuck Massingil, Missouri Department of Agriculture
Dr. Greg Gray and Whitney Baker, University of Iowa, College of Public Health

21. Questions?