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Swine Influenza: Reinforced Diagnostics For a Persistent Virus
Swine Influenza virus (SIV) causes a contagious respiratory disease in pigs, which spreads rapidly within the herd. Main symptoms are fever, coughing, and lethargy. While most pigs recover, it leads to economic losses due to reduced growth, secondary infections, and treatment costs. Commercial vaccines exist but may be less effective due to viral mutations.
At Poulpharm, we provide fast, reliable diagnostics for SIV detection and typing, now including the Hemagglutination Inhibition (HI) test.
How does it work?
The HI test works by measuring the ability of antibodies in a sample to bind Influenza virus, thus inhibiting the agglutination of red blood cells caused by the virus’s hemagglutinin protein.
Three main components — antibodies, influenza virus, and red blood cells (Figure 1) — are mixed in wells of a microtiter plate.
Each row tests different influenza strains against the same set of antibodies (e.g. from animal blood sampling), allowing hemagglutinin subtype identification. Columns represent increasing antibody dilutions, arranged from low to high. (Figure2).
If the antibodies present in the sample neutralize the virus, red blood cells settle at the bottom, forming a small red dot.
In contrast, when viral particles are not neutralized by antibodies, they bind to the red blood cells, forming a diffuse network that prevents the cells from settling.
This setup determines the antibody titer, or the highest dilution at which antibodies still inhibit the virus, providing information on immune response strength and specificity.
Therefore, with the HI test, we can:
- Assess the antigenic similarity between influenza viruses;
- Compare antigenic changes in currently circulating influenza viruses with previous strains or vaccine strains;
- Tell whether antibodies developed against vaccination produce an immune response against that circulating virus.
More information with WGS:
In addition, positive samples can undergo Whole Genome Sequencing (WGS), which allows for a more comprehensive analysis of the virus. WGS provides detailed genetic information about the influenza strains, revealing mutations and variations in both the hemagglutinin (H) and neuraminidase (N) genes, as well as other viral proteins. This in-depth genetic data is essential for tracking the evolution
of the virus and for refiningautogenous vaccines to ensure they match the unique strain profile of each herd.
At Poulpharm, by combining HI testing and WGS, we enhance vaccine efficacy and improve disease management outcomes, providing a robust, tailored approach to Swine Influenza control.
We are also committed to continuously refining our methods and reporting about SIV epidemiology.
