In a series of seven experiments, the virulent Nichols strain of Treponema pallidum was shown to attach and replicate on the surface of tissue culture cells of cottontail rabbit epithelium (SflEp) growing in conventional monolayer cultures under an atmosphere of 1.5% oxygen. Five days after inoculation of 106 T. pallidum, the number of treponemes had increased to between 8 x 106 and 2.59 x 107. The viability of harvested organisms ranged from 86 to 97%. The number of T. pallidum continued to increase, generally reaching a plateau between days 9 and 12 of incubation, with increases ranging up to 100-fold and averaging 49fold. There appeared to be a ceiling of multiplication of about 2 x 108 irrespective of the inoculum, which ranged from 106 to 108 T. pallidum. Concurrent deoxyribonucleic acid assays were performed on the cultures containing T. pallidum to obtain further evidence of replication. Significant increases in treponemal deoxyribonucleic acid were observed when the inocula ranged from 106 to 107, with the greatest increases, as might be expected, being in the former group. There was also excellent correlation in the amount of deoxyribonucleic acid per treponeme; 908

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Recently, with an available serological hepatitis E virus diagnostic kit, the prevalence of IgG antibody to hepatitis E virus among Chinese subjects in Taiwan was evaluated by means of a solid-phase enzyme-linked immunoassay based on two recombinant hepatitis E virus antigens. The overall prevalence of hepatitis E virus antibody was 10.7% among 384 healthy subjects older than 20 yr but only 0.3% among 600 schoolchildren and young adolescents younger than 20 yr (p < 0.0001). Serial serum samples from 32 hepatitis E virus antibody-positive healthy subjects showed 84% of them to have antibodies persisting more than 3 to 8 yr. Among patients with viral hepatitis, IgG hepatitis E virus antibody was detected in 10% of 10 patients with acute hepatitis A, in 9.5% of 63 patients with acute hepatitis B and in 13.9% of 36 patients with acute posttransfusion hepatitis C. Of 77 patients with sporadic non-A, non-B hepatitis, IgG hepatitis E virus antibody was detected in 18.9% of 53 patients positive for antibody to hepatitis C virus and in 45.8% of 24 patients negative for hepatitis C virus antibody (p < 0.03). Most of our hepatitis E virus antibody-positive normal subjects and patients had never been abroad. These findings demonstrate that sporadic or subclinical hepatitis E virus infections also exist among the Chinese subjects in Taiwan. Hepatitis E virus infection may play an important role in patients with hepatitis C virus antibody-negative sporadic non-A, non-B hepatitis. IgG hepatitis E virus antibody in the sera of normal subjects may last for more than 8 yr.

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