Preventive effects of Mycobacterium vaccae on HIV-associated tuberculosis: a systematic review

Abstract

Objective: To evaluate the effectiveness and safety of Mycobacterium vaccae (M.vaccae, MV) for prevention of HIV-associated tuberculosis (TB).

Methods: MEDLINE, Embase, Biosis, the Cochrane Central Register of Controlled Trials, SCI, CBM, VIP, and CNKI were searched for relevant randomized controlled trials (RCTs) and non-randomized controlled trials (NRCTs). The GRADE approach was used for quality assessment. Data were analyzed using RevMan 5.0 software.

Results: were described or pooled using relative risks (RRs) for binary outcomes with 95% confidence intervals (CIs). Results Seven studies were included, and the methodological quality assessment found there was a risk of methodological bias. The evidence quality of the critical endpoint was moderate. The incidence of definite TB was (33/1006 vs. 52/1007, P = 0.03). The levels of IFN-γ response to M. vaccae sonicate (MVS) in MV recipients increased compared to baseline or control groups after three or five doses. MV recipients' level of lymphocyte proliferation assays (LPAs) in response to MVS was higher than that of the saline group after a five-dose series (RR = 2.49, 95% CI 1.40 to 4.41, P = 0.002). Compared to hepatitis B vaccine (HBV) recipients, LPAs to MVS were not significantly different in the MV group vs. saline group, or vs. HBV, after a three-dose series (RR and 95% CI were 0.20 (-0.03 to 0.44) and 1.13 (0.26 to 4.91), respectively). Changes in CD4+ cell count and HIV viral load after immunization were not statistically significant. MV immunization had no systematic adverse effects.

Conclusion: The current evidence indicates that MV is safe and well-tolerated. It appears to prevent HIV-infected patients with CD4+≥ 200/mm(3) from contracting TB by enhancing their immunogenicity. Yet, because of the relatively low quality of the available evidence, well-designed and -conducted RCTs are needed.