Avian malaria and bird humoral immune response

Background: Plasmodium parasites are known to impose fitness costs on their vertebrate hosts. Some of these costs are due to the activation of the immune response, which may divert resources away from self-maintenance. Plasmodium parasites may also immuno-deplete their hosts. Thus, infected individuals may be less able to mount an immune response to a new pathogen than uninfected ones. However, this has been poorly investigated.

Methods: The effect of Plasmodium infection on bird humoral immune response when encountering a novel antigen was tested. A laboratory experiment was conducted on canaries (Serinus canaria) experimentally infected with Plasmodium relictum (lineage SGS1) under controlled conditions. Birds were immune challenged with an intra-pectoral injection of a novel non-pathogenic antigen (keyhole limpet haemocyanin, KLH). One week later they were challenged again. The immune responses to the primary and to the secondary contacts were quantified as anti-KLH antibody produ...