Development of two indirect ELISAs using purified recombinant viral proteins to detect myxoma virus-antigen specific antibodies in rabbit sera

Despite the use of effective vaccines, myxomatosis remains a blight on European rabbit farms. The causative agent, myxoma virus (MYXV), is endemic in wild populations of leporids on the Iberian Peninsula. The detection of specific anti-MYXV antibodies in rabbit sera provides an essential part of control and epidemiological programs in both wild and domestic rabbits. Currently, the detection of specific antibodies is carried out by indirect (i)ELISA and competitive (c)ELISA, both using complete MYXV as antigen which requires stringent biosecurity controls. In this study, two full-length recombinant (r) viral proteins, rM022 and rM115, were shown to be antigenic and fit for the development of independent iELISAs for the detection of anti-MYXV antibodies in rabbit sera. The two iELISAs were optimized using a panel of 259 sera that had previously been characterized using commercially available iELISAs. The rM022 and rM115 based iELISAs in receiver operating characteristic (ROC) analysis showed areas under curve (AUC) values > 0.9 with specificities of 83.65% (rM022) and 75% (rM115) and sensitivities of 90.97% (rM022) and 96.77% (rM115), respectively. The use of recombinant proteins to detect anti-MYXV antibodies in rabbit sera shows promise as complementary analyses to existing ELISAs and provide valuable additional information regarding the presence of antigen-specific antibodies following vaccination. Furthermore, this study offers significant value by enabling a detailed characterization of viral proteins M022 and M115, particularly in terms of their antigenicity. Understanding the antigenic properties of viral proteins is crucial as it facilitates the development of more effective vaccines and enables accurate assessment of the immune response. This has a major impact on improving protection and monitoring viral infections, providing a solid foundation for the development of new prevention and treatment strategies.