Background: Recent and independent molecular studies have shown an association between human endogenous retroviruses type "W" family (HERV-W) and schizophrenia, mostly by polymerase chain reaction studies, but none has yet addressed specific antigen detection in living patients.
Methods: Forty-nine schizophrenic patients and an equivalent number of healthy control subjects were included in the present exploratory study. The HERV-W GAG and envelope (ENV) proteins were quantified in the serum with a dedicated immunoassay set-up with specific monoclonal antibodies to either antigen.
Results: In schizophrenic patients, positive antigenemia for ENV was found in 23 of 49 (47%) and for GAG in 24 of 49 (49%). Only 1 of 30 (3%) for ENV and 2 of 49 (4%) for GAG were positive in blood donors (p < .01 for ENV; p < .001 for GAG). Interestingly, bioclinical data analyses revealed significant correlation between GAG or ENV antigenemia (a protein causing dysimmune inflammatory effects) and C-reactive protein (CRP) levels (a systemic inflammation biomarker).
Conclusions: Frequently elevated CRP has previously been described in schizophrenic patients and has been shown to match with an evolution toward cognitive deficit and neuronal loss. Elsewhere viruses such as influenza, long-associated with risk for schizophrenia through perinatal infections, have been shown to activate HERV-W elements in human cells. We therefore discuss a relationship between environment factors long-associated with early risk, genetic factors represented by this endogenous family, the production of its pro-inflammatory ENV protein and known "inflammation-mediated" neurotoxicity, as a possible hypothesis for a pathogenic cascade in association with HERV-W. Our present results thus confirm that HERV-W studies have opened a novel avenue of research in schizophrenia.