A pilot study of SRL 172 (killed Mycobacterium vaccae) in healthy chronic hepatitis B carriers and hepatitis B vaccine non-responders.
OBJECTIVE
To assess possible development of immunity to HBV by the use of hepatitis B vaccine in combination with the adjuvant M. vaccae (SRL 172) in healthy chronic HBsAg carriers and in healthy non-responders to hepatitis B vaccine.


OBJECTIVE
To utilise the known immuno-stimulatory effects of SRL 172 (heat-killed M. vaccae) on chronic carriers of HBV and non-responders to hepatitis B vaccine to overcome the respective 'immune-tolerance' and 'immune blindness' observed in these conditions and develop immunity to hepatitis B.


METHODS
35 suitable healthy HBsAg carriers were randomised to receive hepatitis B vaccine together with either placebo or SRL172 by the intradermal route on one occasion. 23 HB vaccine non-responders were randomised in the same way, and similarly given vaccine with either SRL 172 or placebo. The HBsAg carrier subjects were followed-up for 12 months to monitor changes in HBV markers, anti-HBs, clinical chemistry, immunological and clinical status. The HB vaccine non-responders were reassessed for the development of anti-HBs at three months post-immunisation.


RESULTS
This pilot study provided evidence that SRL172 was moderately well tolerated and safe. One HB vaccine/placebo recipient (with initial prevaccination high HBV load) became HBV DNA negative and remained so for the 12-month duration of the study. Vaccine plus SRL172 helped induce measurably higher anti-HBs titres in HB vaccine nonresponders, however, because of relatively small participant numbers, statistically significant results were not obtained.


CONCLUSIONS
Based on the development of anti-HBs in non-responders, the non-proprietary mixing of vaccine with SRL172 does not destroy immunogenicity of the vaccine and thus provides an opportunity to conduct further studies of this combination in hepatitis B vaccine non-responders. HB vaccine plus SRL 172 when given on one occasion is ineffective in treating HBsAg carriers. Interesting differences between the treatment groups were observed in HB viral load responses at 3 months post-vaccination. Consideration should be given to further studies using multi-dose regimens.
Goldwater
Paul N
PN
Microbiology and Infectious Diseases Department, Women's and Children Hospital, North Adelaide, South Australia. goldwaterp@mail.wch.sa.gov.au
D000293:Adolescent; D000328:Adult; D001428:Bacterial Vaccines / Q000009:adverse effects / Q000276:immunology*; D015415:Biomarkers; D002353:Carrier State / Q000821:virology; D002648:Child; D005260:Female; D006510:Hepatitis B Antibodies / Q000097:blood; D017325:Hepatitis B Vaccines / Q000009:adverse effects / Q000276:immunology*; D019694:Hepatitis B, Chronic / Q000517:prevention & control*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010865:Pilot Projects; D019562:Viral Load
D001428:Bacterial Vaccines; D015415:Biomarkers; D006510:Hepatitis B Antibodies; D017325:Hepatitis B Vaccines; C451081:SRL172