title: Bacillus Calmette-Guérin-inoculation at different time points influences the outcome of C57BL/6 mice infected with Plasmodium chabaudi chabaudi AS.
abstract: Bacillus Calmette-Guérin (BCG) is an attenuated Mycobacterium tuberculosis vaccine. We performed a series of co-infection experiments with BCG-Plasmodium chabaudi chabaudi Landau, 1965 AS using C57BL/6 mice to analyse whether BCG can affect the development of protective immunity to infection with Plasmodium spp. and the mechanism of this protection. We divided mice into four groups: BCG-inoculation 4 weeks prior to P. c. chabaudi AS infection (B-4w-Pc); simultaneous BCG-inoculation and P. c. chabaudi AS infection (Pc+B); BCG-inoculation 3 days post P. c. chabaudi AS (Pc-3-B) infection; and mono-P. c. chabaudi AS infection as control (Pc). The parasitemia level in the B-4w-Pc group was noticeably higher than control group at 6-19 days post infection (dpi). Compared with the control group, the proportion of CD4(+)CD69(+) T cells was significantly reduced 5, 8 and 12 dpi, but the proportion of CD4(+)CD25(+)Foxp3(+) Tregs was significantly increased in the B-4w-Pc group on 5 and 8 dpi. The B-4w-Pc group also demonstrated reduced levels of IFN-γ and TNF-α on 5 and 8 dpi and significantly elevated level of IL-10 on 12 dpi. There were significantly fewer mDCs (CD11c(+)CD11b(+)) and pDCs (CD11c(+)B220(+)) in the B-4w-Pc group than the control group at all the time points post infection and the expression of MHC II was noticeably reduced on day 8 pi. Our findings confirmed that BCG inoculation prior to Plasmodium infection resulted in excessive activation and proliferation of Tregs and upregulation of anti-inflammatory mediators, which inhibited establishment of a Th1-dominant immune response during the early stages of Plasmodium infection by inhibiting dendritive cells response. BCG inoculation prior to P. c. chabaudi AS infection may contribute to overgrowth of parasites as well as mortality in mice.
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China.|Aristogenesis Center, Hospital of People's Liberation Army, Shenyang, China.
authors.forename: Dong-Hua
authors.initials: DH
authors.lastname: Cao
authors.affiliation: Department of Microbiology and Parasitology, College of Basic Medical Sciences, China Medical University, Shenyang, China;
authors.forename: Ji-Chun
authors.initials: JC
authors.lastname: Wang
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China;
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China;
authors.forename: Yun-Ting
authors.initials: YT
authors.lastname: Du
authors.affiliation: Department of Entomology, The Pennsylvania State University, University Park, Pennsylvania, USA.
authors.forename: Li-Wang
authors.initials: LW
authors.lastname: Cui
authors.affiliation: Department of Immunology, College of Basic Medical Sciences, China Medical University, Shenyang, China;
authors.forename: Ya-Ming
authors.initials: YM
authors.lastname: Cao
mesh_terms: D000818:Animals; D001500:BCG Vaccine / Q000276:immunology*; D008288:Malaria / Q000276:immunology* / Q000503:physiopathology; D051379:Mice; D008810:Mice, Inbred C57BL; D018512:Parasitemia / Q000276:immunology / Q000503:physiopathology; D016788:Plasmodium chabaudi; D013997:Time Factors
chemical_list: D001500:BCG Vaccine
keywords: BCG; co-infection; murine malarial parasite; protective immunity