Footprints of BK and JC polyomaviruses in specimens from females affected by spontaneous abortion

STUDY QUESTION Are JC polyomavirus (JCPyV) and BK polyomavirus (BKPyV) infections associated with spontaneous abortion (SA)? SUMMARY ANSWER There is no association of JCPyV or BKPyV with SA. WHAT IS KNOWN ALREADY A large number of risk factors have been associated with SA. The role of polyomaviruses, including JCPyV and BKPyV, in SA remains to be clarified. STUDY DESIGN, SIZE, DURATION This is a case-control study including women affected by spontaneous abortion (SA, n = 100, the cases) and women who underwent voluntary interruption of pregnancy (VI, n = 100, the controls). PARTICIPANTS/MATERIALS, SETTING, METHODS Viral DNAs were investigated by qualitative PCR and quantitative droplet-digital PCR (ddPCR) in matched chorionic villi tissues and peripheral blood mononuclear cells (PBMCs) from SA (n = 100) and VI (n = 100). Indirect ELISAs with mimotopes/synthetic peptides corresponding to JCPyV and BKPyV viral capsid protein 1 epitopes were then employed to investigate specific IgG antibodies against JCPyV and BKPyV in human sera from SA (n = 80) and VI (n = 80) cohorts. MAIN RESULTS AND THE ROLE OF CHANCE JCPyV DNA was detected in 51% and 61% of SA and VI samples, respectively, with a mean viral DNA load of 7.92 copy/10 4 cells in SA and 5.91 copy/10 4 cells in VI (P > 0.05); BKPyV DNA was detected in 11% and 12% of SA and VI specimens, respectively, with a mean viral DNA load of 2.7 copy/10 4 cells in SA and 3.08 copy/10 4 cells in VI (P > 0.05). JCPyV was more prevalent than BKPyV in both SA and VI specimens (P < 0.0001). In PBMCs from the SA and VI cohorts, JCPyV DNA was detected with a prevalence of 8% and 12%, respectively, with a mean viral DNA load of 2.29 copy/10 4 cells in SA and 1.88 copy/10 4 cells in VI (P > 0.05). The overall prevalence of serum IgG antibodies against JCPyV detected by indirect ELISAs was 52.5% and 48.7% in SA and VI groups, respectively, whereas BKPyV-positive sera were found in 80% SA and 78.7% VI samples. LIMITATIONS, REASONS FOR CAUTION This study did not investigate the presence of viral mRNA and/or proteins, which are indicative of an active viral infection, and these might be taken into consideration in future studies. WIDER IMPLICATIONS OF THE FINDINGS JCPyV and BKPyV DNA sequences were detected and quantitatively analyzed for the first time by PCR/ddPCR in chorionic villi tissues and PBMCs from SA and VI specimens. Moreover specific immunological approaches detected serum IgG against JCPyV/BKPyV. Statistical analyses, however, do not indicate an association between these polyomaviruses and SA.