Equine influenza serological methods.

The research article examines various serologic tests used to detect antibodies for Equine Influenza Virus (EIV). Tests such as the Hemagglutination-Inhibition (HI), Single Radial Hemolysis (SRH), and serum micro-neutralization tests are typically used for different purposes, which range from retrospective diagnosis to measuring immune responses to EIV vaccines.

Hemagglutination-Inhibition Test

• The Hemagglutination-Inhibition (HI) test is a widely used serological method for identifying antibodies against EIV. The process involves observing red blood cells’ clumping or hemagglutination as a response to a virus.
• This test, however, presents some complications. Equine serum contains inhibitors of hemagglutination, which can make interpreting the HI assay results challenging. Hence, the research introduces alternative protocols such as receptor-destroying enzyme, periodate, and trypsin-periodate for the removal of these inhibitors.
• The article also noted that results could be manipulated when testing for specific strains of EIV, such as H3N8. This occurs when the HI test antigen is pretreated with substances like Tween-80 and ether.

Single Radial Hemolysis Test

• The Single Radial Hemolysis (SRH) test is another common method for detecting EIV antibodies. The study notes that this test could offer more accurate correlations between serum antibody titers and protection from the disease itself.

Serum Micro-neutralization Test

• The serum micro-neutralization test is commonly included with HI and SRH for our purposes.

Other Tests

• While the HI and SRH are the primary focus, the research paper mentions other specialized tests such as the neuraminidase-inhibition assay, which is used for subtyping, and ELISA, used for measuring different specific antibody isotypes. These tests are not however elaborated in this context.