Evaluation of equine infectious anemia virus core proteins produced in a baculovirus expression system in agar gel immunodiffusion test and enzyme-linked immunosorbent assay.

The researchers examined the effectiveness of using equine infectious anemia virus (EIAV) core proteins in two types of tests, the agar gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA), to avoid false-positive reactions in horse serum testing. The core proteins were successfully obtained from a baculovirus expression system and resulted in no false-positive reactions, unlike the currently used antigen, Nisseiken, when used in ELISA tests.

Expression and Production of Core Proteins

• This research aimed to improve the accuracy of horse serum testing for equine infectious anemia virus (EIAV).
• The researchers used a baculovirus expression system to produce EIAV core proteins, Gag and p26.
• These proteins were then used as antigens in two types of commonly used diagnostic tests: agar gel immunodiffusion (AGID) and enzyme-linked immunosorbent assay (ELISA).

Testing and Results

• The researchers tested seventy-six horse sera using these expressed antigens in AGID and ELISA tests.
• Unfortunately, when using the Nisseiken antigen in AGID tests, a false-positive reaction occurred in these sera. This implies a reduction in the reliability of tests performed with the Nisseiken antigen.
• However, no such false-positive reactions were observed when both the expressed antigens (Gag and p26) were used in the tests.
• Additionally, when these horse sera were tested using ELISA, again, a high background (indicating a false-positive reaction) was observed with the Nisseiken antigen. However, the newly expressed antigens Gag and p26 reacted strongly and accurately with positive sera from horses immunized with the Nisseiken antigen.

Conclusion

• This study demonstrated that EIAV core proteins (Gag and p26) obtained from a baculovirus expression system showed a higher degree of accuracy in both AGID and ELISA tests when compared with the Nisseiken antigen.
• These proteins also showed stronger reactions with horse sera that tested positive, indicating potential efficiency for diagnostic purposes.
• Thus, using these proteins could potentially improve the accuracy of horse serum testing for EIAV, decreasing the occurrence of false-positive results, a common issue with the use of the Nisseiken antigen.