Comprehensive genomic characterization of herpes B virus isolated from a wild long-tailed macaque reveals conserved entry mechanisms and zoonotic potential
ABSTRACT Herpes B virus (BV; Macacine alphaherpesvirus 1) is a zoonotic alphaherpesvirus endemic in macaques that can cause severe, often fatal encephalomyelitis in humans. However, genomic data from wild macaque populations remain limited. Here, we report the isolation and genomic characterization of a BV strain from a wild long-tailed macaque (Macaca fascicularis) in Thailand and assess its zoonotic potential. Among 138 macaques screened across six populations, BV shedding was detected in a single oral swab (0.72%). The virus (BV/Thailand/Ranong_TPK5/2024) was successfully isolated and propagated in Vero and LLC-MK2 cells, with higher replication efficiency observed in Vero cells. The TPK5 isolate exhibited a high infectious titre (8 × 10⁷ PFU/mL), and transmission electron microscopy confirmed typical herpesvirus morphology. Whole-genome sequencing achieved deep coverage (∼20,974×) and revealed 98.4% identity to a reference strain (E90–136) from captive long-tailed macaques. Phylogenetic analyses of 12 envelope glycoproteins demonstrated host-associated clustering, with the TPK5 isolate grouping within the long-tailed macaque lineage. Key entry glycoproteins (gB, gD, gH, and gL) were highly conserved among macaques but diverged from human herpes simplex viruses. In contrast, host receptors nectin-1 and nectin-2 were highly conserved between macaques and humans (≥95% identity), suggesting preserved receptor compatibility. Despite the low prevalence of shedding, the isolation of an infectious BV strain from an asymptomatic macaque highlights an ongoing zoonotic risk. Conservation of viral entry mechanisms and host receptors supports the potential for cross-species transmission in high human–macaque interface settings.