Investigation of the potential relationship between influenza A virus (IAV) and Streptococcus suis infections in weanling piglets

Danielle HopkinsAdvisors: Zvonimir Poljak, Vahab Farzan, Helena Grgić, Robert Friendship

Department of Population Medicine, University of Guelph

The Interaction• A direct interaction

between these pathogens has been

proven in a cell culture study (Wang et al.

2013)

Streptococcus suis• a bacterium that colonizes in

the tonsils of all piglets: there are 35 serotypes; some serotypes are present in healthy pigs but a few

serotypes cause clinical disease

Influenza• a virus that causes piglets to become ill for a short period of time, leaving them susceptible

to secondary infection

BACKGROUND METHODOLOGY

1. Wang, Y., Gagnon, C.A., Savard, C., Music, N., Srednik, M., Segura, M., Lachance, C., Bellehumeur, C., and Gottschalk, M. (2013). Capsular salic acid of Streptococcus suis serotype 2 binds to swine influenza virus and enhances bacterial interactions with virus infected tracheal epithelial cells. Infection and Immunity, 81:4498-4508

Acknowledgements: This work is funded by Swine Improvement Porc, and the University of Guelph/OMAFRA Research Partnership. The participation of pork producers is greatly appreciated..

REFERENCES

1. Very important pathogens • S. suis and IAV are commonly present on swine farms and both are associated with production losses

2. Increased scientific and epidemiological knowledge• If a potential relationship between these pathogens exists, it could help explain why sporadic outbreaks of meningitis due to

Streptococcus suis occur

3.Implementation of control and prevention measures• Increased understanding of the interaction between these pathogens either on a pig level or farm level basis, will be beneficial in designing effective prevention and control methods

PRELIMINARY RESULTS

1: Case Selectio

n

• Identify case positive based on clinical signs for acute meningitis due to S. suis infection• Collect 1meningeal swab for bacterial culture, 2nasal swabs for detection of IAV, 3blood samples for

different assays related to historical and recent exposure to IAV, and 4tissue samples for genetic testing

2: Control

• Age-matched pen mate that appear healthy. Collect swabs and blood samples to determine IAV shedding and history, and genetic markers

3: Testing

• Confirm clinical cases are indeed due to S. suis by bacteriological culture and identify serotypes• Identify current IAV status of cases and controls by PCR* and virus isolation• Identify historical exposure to IAV by HI* and VN* tests and recent exposure by IgM ELISA

4: Analysis • Difference between cases and controls will be tested using logistic regression

Paddling piglet: http://www.nadis.org.uk/bulletins/glaessers

-disease.aspx

Heathy piglet: https://www.hiprofeeds.com/products/c

a/hog/

Growing virus to PCR : http://www.123rf.com

PRELIMINARY CONCLUSIONS AND BENEFITS TO SWINE INDUSTRY

Tonsil Meningeal 0

2

4

6

8

10

12

Case

Control

Bacterial Swabs

Num

ber

of p

igle

ts p

ositi

ve fo

r S.

suis

Fig 1. Represents the number of positive S. suis results following

culture analysis conducted by AHL at the University of Guelph. Positive results were based on meningeal and tonsil swabs collected from

cases and controls

Preliminary Analysis*• 92% (11/12) of bacterial swabs from cases positive for S.suis• 83% (10/12) of bacterial swabs from controls positive for S.suis• Currently undergoing serotyping and IAV status testing

* Key message- the accuracy of case selection and high prevalence of S. suis in both the cases and controls

Samples collected presently:• A total of 12 cases and controls were collected from single farm over a two

week period when S. suis was causing higher than average (>5%) mortality rates within the nursery, the following are the results of preliminary bacterial analysis: