Genetic analysis of varicella-zoster virus in the aqueous humor in uveitis with severe hyphema

Genetic variations have been identified in the genome of varicella-zoster virus (VZV) strains using vesicle fluid, varicella scabs and throat swab samples. We report a rare case of VZV-associated uveitis with severe hyphema, which was immediately diagnosed by polymerase chain reaction (PCR) using the aqueous humor, in which we were able to analyze the VZV genotype for the first time.

A 16-year-old Japanese boy was referred to our hospital with a 20-day history of unilateral anterior uveitis and 11-day history of hyphema. At presentation, details of the iris, the iridocorneal angle, and the fundus were not visible due to the severe hyphema. Serum anti-VZV IgG and anti-VZV IgM were elevated, and 1.61 × 10⁹ copies/mL of VZV-DNA were detected by real-time PCR using the aqueous humor. As there were no eruptions on his face or body, we diagnosed zoster sine herpete and started intravenous administration of prednisolone and acyclovir. The hyphema completely disappeared 2 weeks after presentation, while sectorial iris atrophy and mild periphlebitis of the fundus became gradually apparent. Anterior inflammation and periphlebitis gradually improved and VZV-DNA in the aqueous humor was reduced to 1.02 × 10⁶ copies/mL at 4 weeks after presentation. Examination by slit lamp microscope revealed no inflammation after 5 months, and VZV-DNA could no longer be detected in the aqueous humor. Serum anti-VZV IgG and anti-VZV IgM also showed a gradual decrease along with improvement in ocular inflammation. The genetic analysis of multiple open reading frames and the R5 variable repeat region in the VZV genes, using DNA extracted from the aqueous humor at presentation, showed that the isolate was a wild-type clade 2 VZV strain (prevalent in Japan and surrounding countries) with R5A allele and one SNP unique to clade 1 (both are major types in Europe and North America).

VZV-associated uveitis may develop hyphema that obscures ocular inflammation, thus PCR analysis using the aqueous humor is the key investigation necessary for the diagnosis. The measurement of VZV-DNA copies by real-time PCR would be useful for evaluation of therapeutic effects. We could amplify and analyze VZV genotype using the aqueous humor including a very large number of VZV-DNA copies (1.61 × 10⁹ copies/mL).