Varicella-zoster virus (VZV) belongs to the group of human α-herpesvirus, which can be transmitted in the population by respiratory droplets or vesicular fluid from patients (Arvin, 2001) and is a human host restricted pathogen (Zerboni et al., 2014). Initial infection with VZV causes Varicella, mostly in childhood. Varicella usually presents as a mild, self-limiting disease that usually resolves spontaneously within a week or so in healthy children, but in a small number of immunocompromised or defective children, varicella infection may cause serious complications such as pneumonia and encephalitis, and in severe cases, even death (Tommasi and Breuer, 2022). As the host ages or other factors cause immunity to decline, the latent virus will be activated again and the virus will replicate and spread along the peripheral nerves, forming herpes zoster (HZ) (Anon, 2023). The attack rate of herpes zoster increases notably with age or immunosuppression (Sampathkumar et al., 2009), which is found predominantly the over 50 age group. Moreover, the occurrence of HZ is normally accompanied by severe neuralgia (Arnou et al., 2011), such as postherpetic neuralgia (PHN) (Gershon et al., 2015a). PHN can be severe and can last for months or even years, greatly affecting the mind and body health of patients and causing a social burden in an aging society. Recent studies suggest that COVID-19 vaccination may also increase the reactivation rate of VZV, especially in the elderly population (Psichogiou et al., 2021).

Most patients infected with varicella-zoster can be diagnosed with typical clinical symptoms, but a small number of patients may not have the typical skin lesions, which may result in misdiagnosis or underdiagnosis (Zhang et al., 2010, Hosokawa et al., 2016, Miyake et al., 2019, Sigireddi et al., 2018). When specific types of cases are present, it is necessary to rely on laboratory tests. Therefore, a speedy, sensitive and specific VZV detection method is critical for the diagnosis and monitoring of VZV.

VZV envelope contains a variety of glycoproteins that are closely related to viral pathogenicity and immunogenicity, thus these glycoproteins are the focus of VZV-related research currently (Zerboni et al., 2014). The gB protein is an crucial membrane protein located on the surface of VZV, which consists of 931 amino acid and is highly glycosylated (Maresova et al., 2003, Davison and Scott, 1986). The mature gB is cut into two segments (69 kDa and 73 kDa) at the 491RSRR494 furin recognition site (Oliver et al., 2009). The gB protein forms a trimeric structure as characterized by Cyro-Electron Microscopy and X-ray crystallography (Maresova et al., 2003). A pathological hallmark of varicella-zoster virus is the formation of multinucleated cells, and this cell-cell fusion is mediated by the formation of a core complex of the trimeric gB protein with gH and gL heterodimers, which is a prerequisite for virus entry into the cell (Oliver et al., 2009).

At present, the main methods of VZV detection are virus culture, polymerase chain reaction(PCR) and immunological method. The viral isolation method, once the “gold standard” for diagnosing VZV infection (Kennedy and Gershon, 2018), was time consuming and not readily available. To date, PCR represents the gold standard superseding virus isolation (McCollum and Damon, 2014). Also serological detection is a credible diagnostic method for detecting VZV infection and can be used as an adjunct to PCR detection (Shigeta et al., 1981, Smith-Norowitz et al., 2018, Breuer et al., 2008). To date, ELISA detections of VZV are mostly used for the quantitative detection of anti-VZV antibodies. Antibody level in serum can be used for epidemiological investigation of VZV and efficacy assessment of varicella and herpes zoster vaccines (Niu et al., 2022, Liu et al., 2016).

DAS-ELISA based on mAbs has high sensitivity, specificity and efficiency, which is a time-saving and convenient detection method. It can be used as a complementary method for PCR detection and has potential for analysis of large-scale samples (Oura et al., 2013). DAS-ELISA has been widely applied for the routine diagnosis of many pathogens, for instance Porcine deltacoronavirus (Wang et al., 2021), Koi herpesvirus (Li et al., 2021), Tembusu virus (Chen et al., 2014), etc. However, VZV antigen detection method based on gB protein has not been reported.gB protein is abundant on the surface of VZV and its trimeric structure can stimulate a strong immune response, it appears to be a suitable target for the diagnosis of VZV infection.

In this study, we expressed the VZV gB extracellular domain by CHO eukaryotic expression system. Then, mice were immunized with purified recombinant gB protein as immunogen. By cell fusion technology, high-affinity monoclonal antibodies (mAbs) against gB protein were prepared, and the DAS-ELISA was established to detect VZV antigen.