rBCG induces strong antigen-specific T cell responses in rhesus macaques in a prime-boost setting with an adenovirus 35 tuberculosis vaccine vector.
BACKGROUND
BCG vaccination, combined with adenoviral-delivered boosts, represents a reasonable strategy to augment, broaden and prolong immune protection against tuberculosis (TB). We tested BCG (SSI1331) (in 6 animals, delivered intradermally) and a recombinant (rBCG) AFRO-1 expressing perfringolysin (in 6 animals) followed by two boosts (delivered intramuscullary) with non-replicating adenovirus 35 (rAd35) expressing a fusion protein composed of Ag85A, Ag85B and TB10.4, for the capacity to induce antigen-specific cellular immune responses in rhesus macaques (Macaca mulatta). Control animals received diluent (3 animals).


RESULTS
Cellular immune responses were analyzed longitudinally (12 blood draws for each animal) using intracellular cytokine staining (TNF-alpha, IL-2 and IFN-gamma), T cell proliferation was measured in CD4(+), CD8alpha/beta(+), and CD8alpha/alpha(+) T cell subsets and IFN-gamma production was tested in 7 day PBMC cultures (whole blood cell assay, WBA) using Ag85A, Ag85B, TB10.4 recombinant proteins, PPD or BCG as stimuli. Animals primed with AFRO-1 showed i) increased Ag85B-specific IFN-gamma production in the WBA assay (median >400 pg/ml for 6 animals) one week after the first boost with adenoviral-delivered TB-antigens as compared to animals primed with BCG (<200 pg/ml), ii) stronger T cell proliferation in the CD8alpha/alpha(+) T cell subset (proliferative index 17%) as compared to BCG-primed animals (proliferative index 5% in CD8alpha/alpha(+) T cells). Polyfunctional T cells, defined by IFN-gamma, TNF-alpha and IL-2 production were detected in 2/6 animals primed with AFRO-1 directed against Ag85A/b and TB10.4; 4/6 animals primed with BCG showed a Ag85A/b responses, yet only a single animal exhibited Ag85A/b and TB10.4 reactivity.


CONCLUSIONS
AFRO-1 induces qualitatively and quantitatively different cellular immune responses as compared with BCG in rhesus macaques. Increased IFN-gamma-responses and antigen-specific T cell proliferation in the CD8alpha/alpha+ T cell subset represents a valuable marker for vaccine-take in BCG-based TB vaccine trials.
Magalhaes
Isabelle
I
Microbiology, Tumor and Cell Biology Center, Karolinska Institutet, Solna, Sweden.
Sizemore
Donata R
DR
Ahmed
Raija K
RK
Mueller
Stefanie
S
Wehlin
Lena
L
Scanga
Charles
C
Weichold
Frank
F
Schirru
Giulia
G
Pau
Maria Grazia
MG
Goudsmit
Jaap
J
Kühlmann-Berenzon
Sharon
S
Spångberg
Mats
M
Andersson
Jan
J
Gaines
Hans
H
Thorstensson
Rigmor
R
Skeiky
Yasir A W
YA
Sadoff
Jerry
J
Maeurer
Markus
M
D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D000942:Antigens, Bacterial / Q000235:genetics; D001500:BCG Vaccine / Q000008:administration & dosage* / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics; D005260:Female; D005822:Genetic Vectors; D006460:Hemolysin Proteins / Q000235:genetics; D007111:Immunity, Cellular; D007117:Immunization, Secondary; D007371:Interferon-gamma / Q000096:biosynthesis; D008213:Lymphocyte Activation; D008253:Macaca mulatta; D013601:T-Lymphocytes / Q000276:immunology*; D032581:Tuberculosis Vaccines / Q000235:genetics; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000235:genetics
D000942:Antigens, Bacterial; D001500:BCG Vaccine; D001427:Bacterial Toxins; D006460:Hemolysin Proteins; D032581:Tuberculosis Vaccines; D014614:Vaccines, Synthetic; C020452:Clostridium perfringens theta-toxin; D007371:Interferon-gamma