Elevated levels of Merkel cell polyoma virus in the anophthalmic conjunctiva

Abstract

The human ocular surface hosts a paucibacterial resident microbiome and virome. The factors contributing to homeostasis of this mucosal community are presently unknown. To determine the impact of ocular enucleation and prosthesis placement on the ocular surface microbiome, we sampled conjunctival swabs from 20 anophthalmic and 20 fellow-eye intact conjunctiva. DNA was extracted and subjected to quantitative 16S rDNA PCR, biome representational karyotyping (BRiSK), and quantitative PCR (qPCR) confirmation of specific organisms. 16S ribosomal qPCR revealed equivalent bacterial loads between conditions. Biome representational in silico karyotyping (BRiSK) demonstrated comparable bacterial fauna between anophthalmic and intact conjunctiva. Both torque teno virus and Merkel cell polyoma virus (MCPyV) were detected frequently in healthy and anophthalmic conjunctiva. By qPCR, MCPyV was detected in 19/20 anophthalmic samples compared with 5/20 fellow eyes. MCPyV copy number averaged 891 copies/ng in anophthalmic conjunctiva compared with 193 copies/ng in fellow eyes (p < 0.001). These results suggest that enucleation and prosthesis placement affect the ocular surface flora, particularly for the resident virome. As MCPyV has been shown to be the etiologic cause of Merkel cell carcinoma, understanding the mechanisms by which the ocular surface regulates this virus may have clinical importance.

Figure 1

Quantitative (top) and qualitative PCR for 16S ribosomal DNA from anophthalmic (left) and contralateral (right) conjunctiva. Lower images are from ethidium-bromide stained gel electrophoresis. H20 = double distilled water negative control.

Figure 2

A. Quantitative and qualitative PCR for Merkel cell polyoma virus (MCPyV) in control conjunctiva. B. Quantitative and qualitative PCR for MCPyV in conjunctiva of anopththalmic eyes of same subjects. H₂0 = double distilled water negative control. C. Comparison of quantitative MCPyV viral load normalized to actin (see Fig. 1) from anophthalmic and contralateral eyes.