Serum antibody to Sarcoptes scabiei and house dust mite prior to and during infestation with S-scabiei

In this study, serum antibodies to Sarcoptes scabiei var. canis (SS), Derma tophagoides farinae (DF), and D. pteronyssinus (DP) were determined in 19 h ealthy, random-source dogs prior to infestation with scabies then again dur ing a primary infestation, cure and challenge infestation with scabies. Pri or to scabies infestation, serum of II dogs contained faintly detectable am ounts of IgE and/or IgG to proteins in SS extract, probably resulting from sensitization to dust mites that share cross-reactive antigenic epitopes wi th SS. After becoming infested with scabies, the response to SS antigens be came stronger with antibodies appearing to more antigens as the scabies inf estation progressed. Three of the newly recognized proteins were 170, 155 a nd 142/133 kD and could be used in a diagnostic test since antibodies to th em appeared during the primary infestation. In addition, during the primary infestation, 14 of 15 dogs developed IgE to 1-11 new SS proteins in addition to an increase in IgE binding to those pr oteins recognized prior to infestation. Overall, the strongest antibody res ponses (IgE and IgG) were exhibited during cure of the first infestation, w hen dead mites were still present in the stratum corneum. As expected, the antibody response was strong and rapid during challenge when the infestatio n self-cured. The immunogenic SS proteins identified by serum antibody bind ing during challenge, when the hosts self-cured, are candidates for inclusi on in a vaccine. These candidate proteins are 200, 185, 170, 155, 142/133, 112, 97, 74, 57, 45/42, 32 and 22 kD. Some of the proteins in SS that exhibited new or increased antibody binding during the experiment also had IgE and IgG binding to proteins with simila r molecular weights in DF and DP extracts. These results illustrate the dif ficulties involved in understanding and interpreting serum antibody for dev eloping a serological test for the diagnosis of scabies, isolating relevant SS antigens that could be included in a vaccine for prevention of scabies, and for understanding the immune response mechanism to scabies. (C) 2000 E lsevier Science B.V. All rights reserved.