Yaw. Skeiky et al., TRYPANOSOMA-CRUZI ACIDIC RIBOSOMAL P-PROTEIN GENE FAMILY - NOVEL P-PROTEINS ENCODING UNUSUAL CROSS-REACTIVE EPITOPES, The Journal of immunology, 151(10), 1993, pp. 5504-5515
We have cloned and characterized cDNA molecules that encode members of
the acidic ribosomal protein family (TcP proteins) from the protozoan
parasite Trypanosoma cruzi. These proteins have been shown to be anti
genic in individuals with T. cruzi infection. Unlike other known eukar
yotic cells, T. cruzi possesses at least four types of P protein genes
TcP0, TcP1, TcP2a, and TcP2b, each of which is present in multiple co
pies in the genome. These genes are present on at least three differen
t chromosomes. Although the abundance of TcP0, TcP2a, and TcP2b transc
ripts do not appear to vary among the parasite life-cycle stages, TcP1
is predominantly expressed in the epimastigote (insect) stage. TcP0 h
as a C-terminal heptapeptide sequence that is similar to those of arch
aebacterial acidic (P-like) proteins, but the TcP1/P2 proteins termina
te with a shared sequence characteristic of the P proteins of higher e
ukaryotes. The serine residues or other potential phosphorylation site
s typically found within the highly charged C-terminal acidic domain a
re absent in T. cruzi P proteins. Using synthetic peptides, we demonst
rated that approximately 80% of T. cruzi-infected individuals produce
two distinct but cross-reactive anti-P antibody specificities directed
against the C-termini of TcP0 and TcP1/P2. We also expressed the full
length (non-fusion) recombinant human PO and demonstrated that the T.
cruzi anti-P antibodies cross-react with the C-terminal residues of h
uman P-proteins. Conversely, human anti-P protein antibodies in sera f
rom patients with SLE cross-react with the C-terminal epitope of T. cr
uzi TcP1/P2 proteins. The cross-reactivity of anti-TcP antibodies with
human P proteins suggests that, through antigenic conservation, TcP p
roteins may contribute to the development of autoreactive antibodies i
n Chagas' disease patients.