Alphaherpesviruses are highly prevalent in equine populations and co-
infections with more than one of these viruses’ strains frequently diagnosed.
Lytic replication and latency with subsequent reactivation, along with new
episodes of disease, can be influenced by genetic diversity generated by
spontaneous mutation and recombination. Latency enhances virus survival by
providing an epidemiological strategy for long-term maintenance of divergent
strains in animal populations. The alphaherpesviruses equine herpesvirus 1
(EHV-1) and 9 (EHV-9) have recently been shown to cross species barriers,
including a recombinant EHV-1 observed in fatal infections of a polar bear and
Asian rhinoceros. Little is known about the latency and genetic diversity of
EHV-1 and EHV-9, especially among zoo and wild equids. Here, we report
evidence of limited genetic diversity in EHV-9 in zebras, whereas there is
substantial genetic variability in EHV-1. We demonstrate that zebras can be
lytically and latently infected with both viruses concurrently. Such a co-
occurrence of infection in zebras suggests that even relatively slow-evolving
viruses such as equine herpesviruses have the potential to diversify rapidly
by recombination. This has potential consequences for the diagnosis of these
viruses and their management in wild and captive equid populations. View Full-
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