Surrey SARS Cov Analysis and Implications
With the limited amount of data presented, quite a bit can be learned about the SARS CoV sequences found in patients in Surrey, BC. Assuming that the positions sequenced were 26427-26662 and 28768-29357 the following is true for the two or more SARS CoVs identified:
The sequence range crossed over 5 positions of common polymorphisms.
The sequence of the SARS CoVs in Surrey is not consistent with CUHK-Su10, the virus isolated from the mother of the Prince of Wales index case, because they do not have T26477G. For the same reason they are not another unpublished isolate from Hong Kong or a series of isolates from Taiwan (TC1, TC2, TWJ, TWK, TWS, TWY, TWH, TWC2, TWC3). The SARS CoVs are more closely related to two masked palm civet isolates (SZ1, SZ3)than another masked palm civet isolate (SZ16) or a raccoon dog isolate (SZ13). The sequence is not consistent with several unpublished early isolates from Guangzhou (GZ43, GZ60) or the initial GZ01 isolate. One of the SARS CoV from Surrey has the mutation C26600T that is also found in Frankfurt 1, FRA, TWC, HKU39849, and another unpublished sequence from Hong Kong.
Thus, there are at least two SARS CoVs in the Surrey patients and they have mutations that are in common with more recent isolates, including several closely tied to the Metropole Hotel.
The profile of these two or more SARS CoVs in Surrey, BC suggests the following:
The SARS CoVs causing SARS in the spring are not "back in the box".
The recent SARS transmissions did not involve a re-emergence from an animal reservoir.
The SARS CoVs are easily transmitted by patients with "summer cold" symptoms.
Reliance on symptoms associated with the SARS CoVs in the winter and spring does not identify cases in the summer.
The ratio of the two SARS CoV subtypes suggests they may be be traced back to more than two sources in Hong Kong.
Seasonal cofactors may be required for the SARS presentation seen last winter and spring.
Two of five antibody tests failed to detect antibodies to the virus. One of the failed tests is used by the CDC which only detected 8 SARS cases in the US this year.
Nursing home cases in the Toronto area that initially tested positive for SARS CoV may be true positives, although they were declared negative by health officials.
PCR test by Vancouver groups produce false negatives.
The SARS CoVs have been transmitted undetected in Vancouver in May and June.
Detection in July and August was met with comments on OC43 detection and a number of false negative tests.
In spite of SARS CoV detection by 3 antibody tests, PCR tests, and exact matches for regions of four SARS CoV genes, health officials lifted the quarantine on the two nursing homes and allowed visitors. The officials also refused to identify one of the nursing homes with "summer cold" transmission.
Press releases trying to spin the data don't stop transmission.
The SARS CoV is quite happy with health officials in denial.
It is going to be a VERY long fall and winter. |
