MRC Notes
This series is based on notes that I took when I attended the Medical Research Council (MRC) HCV Conference in Ottawa on January 15 &16, 1999. While every attempt has been made to maintain accuracy, you must keep in mind that these are only my personal notes.
Darlene Morrow
Laboratory Testing for Diagnosis and Follow up
By Mel Krajden, M.D.
BC CDC
655 West 12th Street
Vancouver, BC, V5Z 4R4
Tel: 604.660.6044 Fax: 604.660.0403
How good are serological tests for HCV?
The antibody binds to the protein plus the structural protein and S 4 and the envelope.
EIA-3 is 97 percent accurate
Strong EIA 80 IB+ (IB=immunoblot) is 73 x cutoffs
>3x cutoff can be positive or negative.
Between April 97 and March 97 the BC CDC sent out 110,000 notices. The response to the look back was 5%. Approximately 8883 or 8.1 percent were positive. Using RIBA- 23 percent were positive and of those between 85 & 95% were PCR positive. Of the 47% that were indeterminants - between 5 to 16% were PCR positive. Serology cannot distinguish between active and resolved HCV.
Samples - serum must be separated between 4 and 6 hours or there is in nucleotide degradation. Once in individual tubes and separated, the nucleotides are stable at 4 degree Celsius for up to 4 days.
The commercial PCR test costs around $250 Canadian. Amplicor measures betweeen 10 3 - 10 6. Chiron - 0.2- 120 Meq/mL. bDNA 4-10 >fold higher than Amplicor.
Is the HCV load stable over time?
Chiron 10-20%; Amplicor 20-40%.
Reproducibility is 1-4 fold.
*****Clearly there is need for improved standardization. *****
We must be better able to measure the anti-viral efficacy, replication, and the sustained response to therapy.
70 percent of what we see in BC is genotype 1.
We must have better data management. We must utilize information from public health, study populations, intervention and prevention programs, optimizing outcome programs, risk factors, and the disease itself.
Clearly informatics is the key.