Περίληψη:
Varicella-zoster virus (VZV) is a human herpesvirus, which during
primary infection typically causes varicella (chicken pox) and
establishes lifelong latency in sensory and autonomic ganglia. Later in
life, the virus may reactivate to cause herpes zoster (HZ; also known as
shingles). To prevent these diseases, a live-attenuated heterogeneous
vaccine preparation, vOka, is used routinely in many countries
worldwide. Recent studies of another alphaherpesvirus, infectious
laryngotracheitis virus, demonstrate that live-attenuated vaccine
strains can recombine in vivo, creating virulent progeny. These findings
raised concerns about using attenuated herpesvirus vaccines under
conditions that favor recombination. To investigate whether VZV may
undergo recombination, which is a prerequisite for VZV vaccination to
create such conditions, we here analyzed 115 complete VZV genomes. Our
results demonstrate that recombination occurs frequently for VZV. It
thus seems that VZV is fully capable of recombination if given the
opportunity, which may have important implications for continued VZV
vaccination. Although no interclade vaccine-wild-type recombinant
strains were found, intraclade recombinants were frequently detected in
clade 2, which harbors the vaccine strains, suggesting that the vaccine
strains have already been involved in recombination events, either in
vivo or in vitro during passages in cell culture. Finally, previous
partial and complete genomic studies have described strains that do not
cluster phylogenetically to any of the five established clades. The
additional VZV strains sequenced here, in combination with those
previously published, have enabled us to formally define a novel sixth
VZV clade.
IMPORTANCE
Although genetic recombination has been demonstrated to frequently occur
for other human alphaherpesviruses, herpes simplex viruses 1 and 2, only
a few ancient and isolated recent recombination events have hitherto
been demonstrated for VZV. In the present study, we demonstrate that VZV
also frequently undergoes genetic recombination, including strains
belonging to the clade containing the vOKA strain.
Συγγραφείς:
Norberg, Peter
Depledge, Daniel P.
Kundu, Samit
Atkinson,
Claire
Brown, Julianne
Haque, Tanzina
Hussaini, Yusuf and
MacMahon, Eithne
Molyneaux, Pamela
Papaevangelou, Vassiliki and
Sengupta, Nitu
Koay, Evelyn S. C.
Tang, Julian W.
Underhill,
Gillian S.
Grahn, Anna
Studahl, Marie
Breuer, Judith and
Bergstrom, Tomas
