UL23, UL30, and UL5 characterization of HSV1 clinical strains isolated from hematology department patients.

Genotypic diagnosis of HSV drug resistance can be performed routinely in a clinically relevant time. Nevertheless, data about HSV mutations (polymorphism or resistance) is not exhaustive which hinders the interpretation of such tests. The UL23, UL30, and UL5 genes are of greatest interest as these encode, respectively, thymidine kinase, DNA polymerase, and helicase, which, if mutated may affect the effectiveness of acyclovir, foscarnet, cidofovir, and helicase-primase inhibitors. The present study aimed to extensively characterize UL23, UL30, and UL5 genes. A total of 239 clinical HSV1 recovered from patients admitted to the hematology departments of the Lyon teaching hospitals were included in this single-center retrospective study. Drug resistance was evaluated using the neutral red dye-uptake assay, and sequencing using the Sanger method. Additional information on HSV1 natural polymorphism and resistance is now available. Twenty-two amino acid substitutions related to polymorphism were described on UL23 (E43A, L50M, L68R, Q109K, A133V, A136N, S150L, D258N, S263L, P280S, N301S, A316S, M322L, I326V, D330A, D338H, Q342H, T344I, Q349R, V352L, R370W, E371D), and 6 amino acid substitutions on UL30 (G641R, G645D, E649G, G679D, R681L, I966M). Moreover, the UL23 substitution L242P was added to ACV resistance-related mutations. There were 12 substitutions on UL23 (A37S, V70M, S74L, H151N, P154S, P155Q, L159R, E225L, Y248H, Q270R, N303Y, M372I), and 8 on UL5 (L49I, L138V, S173L, A280T, A575V, V600A, A602T, D862N) that remain of unclear significance with regards to drug resistance. The mean (±standard deviation, SD) number of natural polymorphisms in UL23 was 2.53 (±2.55), in UL30 it was 0.83 (±1.02), and in UL5 it was 5.00 (±1.59) There was no association between HSV1 phenotype and the frequency of substitutions. The results reported herein provide valuable new information concerning HSV1 mutations that will assist the interpretation of genotypic assays.