Table. Serologic results for 11 patients from Laos positive by real-time quantitative PCR for the 47-kDa outer membrane protein and a PCR for a fragment of the 56-kDa protein–encoding gene of Orientia tsutsugamushi*.
| Patient | GenBank accession no. of 56-kDa–amplified gene fragment | Highest % identity with GenBank sequences (reference) | |||
|---|---|---|---|---|---|
| IgG/IgM titers, acute phase–late phase | |||||
| Gilliam | Kato | Kawasaki | |||
| LaoUF74 | 64/1,048–64/1,048 | 128/256–128/256 | 128/256–128/256 | EU168798 | These 4 genotypes showed 100% identity with each other and 96.6% with strain BB23 from Thailand (5) |
| LaoUF317 | 2,048/1,024–ND | 128/1,024–ND | 2,048/1,024–ND | EU168799 | |
| LaoUF366 | 2,048/512–2,048/512 | 128/32–128/32 | 2,048/512–2,048/512 | EU168797 | |
| LaoUF396 |
256/1,024–256/1,024 |
128/64–128/64 |
256/1,024–256/1,024 |
EU168796 |
|
| LaoUF220 | 2,048/512–2,048/1,024 | 2,048/512–2,048/512 | 1,024/256– 2,048/512 | EU168801 | These 2 genotypes showed 100% identity with UT150 and UT332, which are related to Karp serotype isolates (6), BB29 from patients in
Thailand (5), and TWyU81 from chiggers in Taiwan (7) |
| LaoUF244 |
1,024/128–ND |
256/64–ND |
128/64–ND |
EU168800 |
|
| LaoUF83 |
128/1,024–ND |
0/1,024–ND |
0/128–ND |
EU168795 |
95.9% with BB23 from
Thailand (5) |
| LaoUF136 |
2,048/1,024–2,048/1,024 |
2,048/1,024–2,048/1,024 |
2,048/1,024–2,048/1,024 |
EU168804 |
99.5% with UT144, UT125, and UT196 from Thailand, which are related to Gilliam serotype isolates (6) |
| LaoUF186 |
128/1,024–2,048/1,024 |
128/1,024–2,048/1,024 |
128/1,024– 2,048/1,024 |
EU168805 |
100% with BB23 from
Thailand (5) |
| LaoUF187 |
256/1,024–256/1,024 |
256/0–256/0 |
0/0–256/1,024 |
EU168803 |
100% with UT144, UT125, and UT196 from Thailand (6) |
| LaoUF238 | 2,048/1,024–2,048/1,024 | 2,048/1,024–2,048/1,024 | 0/512–256/512 | EU168802 | 100% with UT219, UT395, UT221, and UT213, which are related to Karp serotype–related isolates (7), and FPW2031 from Thailand (6) |
*Ig, immunoglobulin; ND, not done. Specific microimunofluorescence assay (IFA) was performed in Marseille, France, by using whole-cell antigens of O. tsutsugamushi serotypes Kato, Gilliam, and Kawasaki. Serotype Karp was not available for serologic assays. An IFA result was positive if 1) titers were >128 for IgG and >64 for IgM, 2) seroconversion was observed in a convalescent-phase serum sample when an acute-phase serum sample was negative, or 3) there was a >4-fold increase in titers between acute- and convalescent-phase serum samples (0 indicates a titer <25).