Protective and therapeutic effects of the resuscitation-promoting factor domain and its mutants against Mycobacterium tuberculosis in mice.
The resuscitation-promoting factor (Rpf), a secretory protein first reported in Micrococcus luteus, plays a critical role in mycobacterial survival and infection. There are five functionally redundant Rpf-like proteins identified in M. tuberculosis (Mtb). All these Rpfs share a conserved Rpf domain (Rpfd) composed of approximately 70 amino acids, which possesses the same biological functions as the full-length Rpf protein. Glutamic acid at position 54 in Rpfd (E54) has been implicated in mediating multiple physiological processes, and a single amino acid substitution at residue E54 can affect the protein biological activity. In order to determine the effects of different amino acid substitutions of E54 in Rpfd on its immunogenic activity, we generated three recombinant Rpfd mutants, Rpfd1 (E54K), Rpfd2 (E54A) and Rpfd3 (E54K and D48A), based on T-cell epitope prediction and tested their potential protective/therapeutic effects against Mtb in mice. Our results demonstrated that replacement of E54 by different amino acids in Rpfd distinctively influenced its resuscitation-promoting activities and Th1-type immune responses induced in mice. Administration of Rpfd2 mutant enhanced Th1-type cellular responses (IFN-γ and IL-2) in mice (P < 0.05, Rpfd2 versus control) and provided effective protection against Mtb in mice by significantly inhibiting the growth of Mtb during the initial stage of infection. Four weeks after the challenge, the slightest pathological injury in lung was observed in the Rpfd2-immunized group among all three Rfpd mutant-immunized groups. Furthermore, Rpfd2 therapy significantly decreased the bacterial load in lung and alleviated histopathological damage in Mtb-infected mice. Together, our results suggest Rpfd2 as a novel effective vaccine candidate against Mtb.
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China Laboratory Animal Center, the Second Military Medical University, Shanghai 200433, China.
Shanmin
S
Zhao
Department of Radiology, the First Affiliated Hospital, Chengdu Medical College, Chengdu, Sichuan 610500, China.
Xiaoqin
X
Song
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
Yong
Y
Zhao
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
Yi
Y
Qiu
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
Fengfeng
F
Mao
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
Caiqin
C
Zhang
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
Bing
B
Bai
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
Hai
H
Zhang
Department of Radiology, the First Affiliated Hospital, Chengdu Medical College, Chengdu, Sichuan 610500, China changhong@fmmu.edu.cn wspjj@163.com.
Shaoping
S
Wu
Division of Infection and Immunology, Laboratory Animal Center, the Fourth Military Medical University, Xi'an, Shaanxi 710032, China changhong@fmmu.edu.cn wspjj@163.com.
Changhong
C
Shi
D019943:Amino Acid Substitution; D000818:Animals; D000995:Antitubercular Agents / Q000276:immunology / Q000627:therapeutic use*; D058491:Bacterial Load; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use*; D001688:Biological Products / Q000276:immunology / Q000627:therapeutic use*; D016207:Cytokines / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use*; D018984:Epitopes, T-Lymphocyte / Q000235:genetics / Q000276:immunology; D006651:Histocytochemistry; D007167:Immunotherapy / Q000379:methods*; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008297:Male; D008807:Mice, Inbred BALB C; D050505:Mutant Proteins / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use; D018417:Th1 Cells / Q000276:immunology; D016896:Treatment Outcome; D014376:Tuberculosis / Q000517:prevention & control* / Q000628:therapy*
D000995:Antitubercular Agents; D001426:Bacterial Proteins; D001688:Biological Products; D016207:Cytokines; D018984:Epitopes, T-Lymphocyte; D050505:Mutant Proteins; D011994:Recombinant Proteins; C113704:resuscitation-promoting factor, bacteria
Mycobacterium tuberculosis; domain; mutant; resuscitation-promoting factor; therapy