To identify herpesviral virions secreted by viral replication, we have established the nuclease-resistance assay (NRA) as a comparative analysis to other conventional assays, including electron microscopy (EM). For this study, we used an efficient experimental in vitro infection model for Alcelaphine herpesvirus 1 (AlHV-1), a gamma herpesvirus, to propagate the virus. The NRA could identify extracellular, cell-free, enveloped virions in the supernatants after 24 hours post inoculation (h.p.i.) of AlHV-1. The results of EM observation were correlated with those of NRA. Mature virions were observed in the clarified, concentrated supernatants from 24 h.p.i. by EM. These results show that sensitivity of the NRA is comparable with that of EM for the identification of mature enveloped virions, which directly presents evidence of herpesviral lytic replication. NRA allows us to differentiate the virus from other member of Herpesviridae, and has extended the possibility of analysis for quantification of shedding viruses when used in conjunction with real-time polymerase chain reaction (PCR).