Antibodies to granulocytic ehrlichiae in white-footed and cotton mice in eastern United States

Serum samples, collected from Peromyscus leucopus (white-footed mouse) or P eromyscus gossypinus (cotton mouse) during 1987 through 1990 in Florida, Ge orgia, Maryland, Mississippi, and North Carolina (USA), and in 1997 in sout hern Connecticut were analyzed by indirect fluorescent antibody (IFA) stain ing methods or Western blot procedures for antibodies to granulocytic ehrli chiae. Of the 82 sera from white-footed mice in Connecticut tested by IFA m ethods with either the BDS or NCH-1 strain of the human granulocytic ehrlic hiosis (HGE) agent, 45 (55%) and 42 (51%) of the samples contained antibodi es to these strains, respectively, at concentrations ranging from 1:80 to 1 :2560. One (2%) of 43 sera from P: leucopus captured in Assateague Island ( Maryland) had a titer of 1:80, while three (20%) of 15 sera from P. gossypi nus, captured in Sapelo Island (Georgia) and four (40%) of 10 sera from cot ton mice caught in Amelia Island (Florida) had antibodies to the NCH-1 stra in at titers of 1:160 to 1:1,280. Fifty five sera from P. leucopus in Cape Hatteras (North Carolina) and 30 sera from P. gossypinus in Mississippi wer e negative. Western blot analyses confirmed seropositivity for 19 (95%) of 20 mouse sera positive by IFA staining methods, including samples from both mouse species captured in Connecticut, Maryland, or Florida. There were ke y banding patterns to proteins having molecular masses of about 44, 80, 105 , 110, or 120 kDa. Both serologic assays can be used to determine if mice h ave been exposed to granulocytic ehrlichiae. These rodents also may be usef ul in surveillance programs to identify endemic sites for HGE and in perfor ming laboratory studies on immune responses to the etiologic agent.