Fig 1.
Similarity among SV40-specific Tag mimotopes (Pep Tag A and Pep Tag D) and other polyomavirus Tag sequences, Panel A and B, respectively.
SV40 (simian virus 40) Tag sequences were compared to the Tags of the following polyomaviruses: BKV (BKPyV, BK polyomavirus), HPyV6 (human polyomavirus 6), HPyV7 (human polyomavirus 7), HPyV9 (human polyomavirus 9), HPyV10 (human polyomavirus 10), HPyV11/STLPyV (human polyomavirus 11), HPyV12 (human polyomavirus 12), JCV (JCPyV, JC polyomavirus), KIV (KIPyV, KI polyomavirus), LPV/AGMPyV (B-lymphotropic polyomavirus), MCV (MCPyV, Merkel cell polyomavirus), SA12 (simian agent virus 12), TSV (TSPyV, Trichodysplasia spinulosa-associated polyomavirus), WUV (WUPyV, WU polyomavirus), and NJPyV (New Jersey polyomavirus, not shown). (http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id=10624).
Fig 2.
Polyomavirus phylogenetic tree based on the large Tag a.a. sequences.
The similarity of large Tag sequences among different polyomaviruses is shown. Note that SV40 (simian virus 40) Tag is more closely related to those of JCV (JCPyV, JC polyomavirus), SA12 (simian agent virus 12), and BKV (BKPyV, BK polyomavirus) than to the Tags of other polyomaviruses: KIV (KIPyV, KI polyomavirus), WUV (WUPyV, WU polyomavirus), HPyV11/STLPyV (human polyomavirus 11), HPyV10 (human polyomavirus 10), HPyV7 (human polyomavirus 7), HPyV6 (human polyomavirus 6), HPyV9 (human polyomavirus 9), LPV/AGMPyV (B-lymphotropic polyomavirus), TSV (TSPyV, Trichodysplasia spinulosa-associated polyomavirus), MCPyV (Merkel cell polyomavirus), HPyV12 (human polyomavirus 12), and NJPyV (New Jersey polyomavirus, not shown) (http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?id510624).
Fig 3.
Simian virus 40 (SV40) genome and the two selected peptides from the early coding region employed in indirect ELISA.
The upper panel represents a circular map of the SV40 genome with map units from 0 to 100 running in a clockwise direction (inner circle, black). The nucleotide (nt) sequence and numbers refer to the 5,243 nucleotide genome of SV40 strain 776 (http://www.ncbi.nlm.nih.gov/genome). Ori marks the origin of viral DNA replication (0/5243 nt). SV40 early and late genes are transcribed in anti-clockwise and clockwise directions, respectively (gray arrows); numbers indicate nt. The large T antigen (T) and small t antigen (t) are encoded by the early region. T antigen exon 1 is encoded from 5,163–4,918 nt and exon 2 from 4,571–2,691 nt, with intron 1 from 4,917 to 4,572 nt. Small t antigen is encoded from 5,163 to 4,639 nt. Viral capsid proteins 1–3 are codified by the late region (VP1, 1,499–2,593 nt; VP2, 562–1,620 nt; and VP3, 916–1,620 nt). A portion of the early coding region is expanded at the bottom of the figure. The selected Tag peptides, Tag A and Tag D, are from exon 2; Tag A encompasses amino acids (a.a.) 669–689 (21 a.a.), and Tag D a.a. 659–682 (24 a.a.). These two Tag epitopes overlap from a.a. 669 to 682.
Fig 4.
Structural characteristics of large T-antigen peptides.
(A) Tag A and (B) Tag D linear peptides were characterized by secondary structure folding domains identified by PSIPRED analysis. (C and D) Tertiary structures of SV40 large T antigen computationally determined with I-TASSER modeling algorithm, with a C-score = –2. Tag A and D both show a partial overlapping localization near the N-terminal native protein domain (magenta sticks in panel C and D, respectively). (E and F) Mesh representation of the large T antigen surface (N-terminal portion) on which Tag A and Tag D are mapped.
Fig 5.
Serologic profile of human serum antibody reactivity to SV40 large T antigen mimotopes Tag A (A), Tag D (B) and Tag A+D (C).
Immunologic data are from healthy subjects (HS). Results are presented as values of OD readings at λ 405 nm for serum samples diluted 1:20 and assayed in indirect ELISA. In this scatter dot plotting, each plot represents the dispersion of individual sample OD values to a mean level, indicated by the long horizontal line inside the scatter with standard error of the mean (SEM) marked by short horizontal lines for each age group. The OD readings of serum samples were stratified by age: 18–30 years (yrs), 31–40 yrs, 41–50 yrs, and 51–65 yrs. Data were analyzed with one way Anova analysis and Newman-Keuls Multiple Comparison test (OD mean, 95% CI). (A) High levels of antibodies against SV40 Tag A in HS aged 18–30 yrs (0.24 OD, 95% CI = 0.21–0.27) vs. HS aged 31–40 yrs (0.18 OD, 95% CI = 0.16–0.20, **P < 0.01), vs. HS aged 41–50 yrs (0.15 OD, 95% CI = 0.14–0.17, ***P < 0.001), vs HS aged 51–65 (0.20 OD, 95% CI = 0.18–0.23, *P<0.05). High levels of antibodies against HS aged 51–65 yrs vs HS aged 41–50 yrs (***P<0.001). (B) Levels of antibodies against SV40 Tag D were not statistically different among age groups of HS (P > 0.01). (C) High levels of antibodies against both SV40 Tag peptides Tag A+D were observed in HS aged 18–30 yrs (0.23 OD, 95% CI = 0.21–0.24) vs. HS aged 31–40 yrs (0.19 OD, 95% CI = 0.17–0.20, **P < 0.01), vs. HS aged 41–50 yrs (0.16 OD, 95% CI = 0.15–0.18, ***P < 0.001), and vs HS aged 51–65 yrs (0.20 OD, 95% CI = 0.18–0.21, *P<0.05). High levels of antibodies against HS aged 51–65 yrs vs HS aged 41–50 yrs (**P<0.01).
Fig 6.
Intra-run and inter-run variability of OD values of human serum antibody reactivity to Tag A and D peptides.
Data are presented as scatter dot plot of OD readings at λ 405 nm, mean and standard error of the mean (SEM) marked by short horizontal lines for each peptide. (A) OD value variability, intra-run. Tag A: mean = 0.19, SEM = 0.006; Tag D: mean = 0.18; SEM = 0.005. (B) OD value variability, inter-run. Tag A: mean = 0.18, SEM = 0.005; Tag D: mean = 0.19, SEM = 0.005.
Table 1.
Prevalence of immunoglobulin G antibodies in sera from healthy subjects reactive with simian virus 40 (SV40) large T-antigen mimotopes.