Amino acid substitutions in the thymidine kinase gene of induced acyclovir-resistant herpes simplex virus type 1

Abstract

Abstract. Acyclovir (ACV) is an antiviral drug of choice in healthcare setting to treat infections caused by herpes viruses, including, but not limited to genital herpes, cold sores, shingles and chicken pox. Acyclovir resistance has emerged significantly due to extensive use and misuse of this antiviral in human, especially in immunocompromised patients. However, it remains unclear about the amino acid substitutions in thymidine (TK) gene, which specifically confer the resistance-associated mutation in herpes simplex virus. Hence, acyclovir-resistant HSV-1 was selected at high concentration (2.0 -4.5 μg/mL), and the TK-gene was subjected to sequencing and genotypic characterization. Genotypic sequences comparison was done using HSV-1 17 (GenBank Accesion no. X14112) for resistance-associated mutation determination whereas HSV-1 KOS, HSV-1 473/08 and HSV clinical isolates sequences were used for polymorphismassociated mutation. The result showed that amino acid substitutions at the non-conserved region (UKM-1: Gln34Lys, UKM-2: Arg32Ser & UKM-5: Arg32Cys) and ATP-binding site (UKM-3: Tyr53End & UKM-4: Ile54Leu) of the TKgene. These discoveries play an important role to extend another dimension to the evolution of acyclovir-resistant HSV-1 and suggest that selection at high ACV concentration induced ACV-resistant HSV-1 evolution. These findings also expand the knowledge on the type of mutations among acyclovir-resistant HSV-1. In conclusion, HSV-1 showed multiple strategies to exhibit acyclovir resistance, including amino acid substitutions in the TK gene.

Goniothalamin Berkesan Secara In Vitro Terhadap Virus Herpes Manusia Jenis 1 Rintang-Acyclovir

“…Ini sebagai langkah proaktif dalam pencarian sebatian aktif antivirus yang berkesan terhadap virus mutan ACV. HHV-1 rintang-ACV yang digunakan mempunyai mutasi pada jujukan gen mengekod timidin kinase (TK) dan polimerase DNA (DNA pol) (Hussin et al, 2013a;Hussin et al, 2013b).…”

“…Sel ginjal monyet hijau Afrika (Vero) daripada spesies Cercopheticus aethiops (American Type Culture Collection, AS) digunakan sebagai sel perumah untuk jangkitan HHV-1. Stok virus HHV-1 pencilan klinikal dan 11 pencilan HHV-1rintang-ACV (Hussin et al, 2013a;Hussin et al, 2013b) diperoleh daripada stok simpanan Makmal Virologi, Jabatan Sains Biologi dan Bioteknologi, Universiti Kebangsaan Malaysia (UKM).…”

“…Sebanyak sebelas pencilan rintang telah berjaya dipencilkan daripada stok pencilan klinikal HHV-1 iaitu UKM-1, UKM-2, UKM-3, UKM-4, UKM-5, UKM-6, UKM-7, UKM-9, UKM-10, UKM-11 dan UKM-12 (Hussin et al, 2013a;Hussin et al, 2013b). Pemencilan dan penulenan HHV-1 rintang-acylclovir dilakukan melalui pendedahan kepada kepekatan ACV melebihi 2.0 µg/mL.…”

“…Penemuan ini adalah penting kerana kebanyakan mutasi HHV-1 berlaku akibat perubahan jujukan yang melibatkan enzim ini. Perbandingan dalam lokasi pengikatan GTN pada TK dan DNA polimerase daripada kajian Fouzi et al (2021) dengan jujukan bermutasi pada kesemua pencilan mutan Hussin et al (2013b) mendapati tiada pertindanan jujukan yang terlibat. Maka, walaupun berlaku mutasi pada TK atau DNA polimerase, GTN masih boleh bertindak terhadap jangkitan HHV-1 tanpa mengira ianya adalah pencilan liar atau pun mutan.…”