Stool serology: development of a non-invasive immunological method for the detection of Enterovirus-specific antibodies in Congo gorilla faeces

The incidence of poliovirus has significantly reduced by as much as 99.9% globally. Alongside this, however, vaccine-associated paralytic poliomyelitis has emerged. Recently, a new recombinant virus (Enterovirus C/Poliovirus) was identified in humans working as eco-guards and in gorillas in Democratic Republic of Congo, including one gorilla with polio-like sequelae. A strain of this recombinant virus (Ibou002) was also isolated from gorilla faeces. In order to assess the potential role of poliovirus infection, we have developed and optimised a protocol, based on the lyophilisation and solubilisation of small volumes of stool extracts, to detect specific antibodies. First, total immunoglobulins was detected in the concentrated stool extracts. Specific antibodies were then detected in 4/16 gorilla samples and 2/3 human samples by western blot using both the polio vaccine antigen and the Ibou002 antigen and by ELISA using the polio vaccine antigen. Humoral responses were greater with the Ibou002 antigen. We therefore suggest that this recombinant virus could lead to a polio-like disease in the endangered western lowland gorilla. The development of a non-invasive method to detect microorganism-specific immunoglobulins from faecal samples opens up new perspectives for the exploration of humoral responses of pathogens in animals and a greater understanding of zoonotic infectious diseases.