Evaluation of diagnostic methods for Helicobacter bilis infection in laboratory mice

Disease-susceptible (C3H) and -resistant (B6) immunocompetent and immunodeficient (C3H-scid and B6-rag1) mice were examined up to 10 weeks after inoculation with Helicobacter bilis (a prototype species of proven virulence). Infection was monitored weekly by use of fecal culture, polymerase chain reaction (PCR) nucleic acid amplification, membrane extract enzyme-linked immunosorbent assay (ELISA), and histologic examination. All mice became infected by three to five weeks after inoculation, on the basis of results of culture and PCR analysis of feces. The PCR analysis was more sensitive than culture at determining infection status, particularly during early infection. None of the mice had evidence of disease by week 10. Immunoglobulin G seroconversion was detectable in C3H mice by week eight and in B6 mice by week nine. Results indicated that culture and PCR analysis are more sensitive than is membrane extract ELISA serologic testing for detecting early infection in individual mice, regardless of genotype or immune status. Results underscore the need for improved seroassays for this important group of murine pathogens.