Genomic Insights: HSV Signatures Among Acanthamoeba Keratitis Cases

Abstract

Purpose : To document the prevalence of Herpes Simplex Virus (HSV) genomic signatures in acanthamoeba hosts recovered from patients with acanthamoeba keratitis (AK).

Methods : Combination of routine culture (non-nutrient agar with Peptone Yeast Glucose broth), PCR and DNA sequencing was used to speciate and genotype acanthamoeba isolates (n=24) recovered from 23 patients presenting at BPEI between 2017-2023. HSV specific PCR was used to screen and confirm the presence of HSV genomic signatures among extracted AK hosts DNA. Collected demographics included risk factors, concomitant herpetic keratitis (HK) diagnosis and treatment, and best-corrected visual acuities (BCVA) at AK diagnosis and last follow-up.

Results : T4 genotype was identified in 96% (23/24) of the samples, while T3 accounted for 4% (1/24). Within the T4 distribution, A. castellanii constituted 71% (17/24), A. polyphaga 13% (3/24), A. triangularis 4% (1/24), A. culbertsoni 4% (1/24), and A. lugdunensis 4% (1/24). The T3 isolate was identified as A. griffini, representing 4% (1/24) of the samples. Positive HSV genomic signatures were observed in 26% (6/24) of the isolates, with 33% (2/6) positive for HSV-1, 50% (3/6) for HSV-2, and 17% (1/6) positive for both. All AK isolates with HSV signatures exhibited T4 genotypes. Patients' ages ranged from 19 to 67 (M=50, SD=16), with 35% female and 65% male representation. CL use was identified as the risk factor in 88% (21/24) of the samples, encompassing 83% (5/6) of patients with HSV signatures and 89% (16/18) of those without. A total of 45.8% (11/24) of the patients were initially diagnosed with HK and received antiviral treatment. Among patients with HSV, 50% (3/6) were initially diagnosed as HK. In the HSV-negative group, 44% (8/18) were initially diagnosed as HK and received antiviral treatment. Patients with HSV displayed an average BCVA of 1.43 and 0.53 LogMAR at diagnosis and final follow-up, respectively. Those without HSV exhibited an average BCVA of 1.85 and 0.92 LogMAR at diagnosis and final follow-up.

Conclusions : Over 40% of AK samples were misdiagnosed as HK, with over 20% displaying positive HSV genomic signatures. The prevalent genotype was T4, and A. castellanii was the most frequent species. HSV-2 predominated as the genomic signature, with simultaneous detection of HSV-1 and HSV-2 in one sample. Contact lens use was the sole identified risk factor. Patients with HSV signatures exhibited superior BCVA.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.