APV are increasingly being detected and characterized by PCR, Restriction fragment length polymorphism (RFLP), Southern blot hybridization, and cycle sequencing, directed at specific genes such as the 4b core protein gene [22, 23] . PCR allows for sensitive and specific detection of viral nucleic acids and has been shown to increase the diagnostic sensitivity for many viral pathogens when compared to culture. A PCR amplicon sequence allows a rapid search for homologous sequences in gene databases, to verify and identify the virus in question and to address phylogenetic relationships. Detection by realtime PCR has been used to identify recombinant APV from individual plaques [74] . This method eliminates the need for amplification and hybridization from the transient dominant protocol and results in significant savings of time at each round of plaque purification [74] .