Postexposure immunization with modified vaccinia virus Ankara or conventional Lister vaccine provides solid protection in a murine model of human smallpox.
BACKGROUND
Decades after the cessation of smallpox vaccination, the potential of the deliberate release of pathogenic orthopoxviruses has forced a reconsideration of using these extremely efficient human vaccines. Scenarios of sudden biothreats have prompted demand for rapidly protective vaccination. However, the feasibility of short-term vaccination (i.e., vaccination shortly before exposure) with vaccinia virus (VACV) is uncertain.


METHODS
We tested the rapid protective capacity of vaccines based on VACV strain Lister (VACV-Lister) and on modified VACV Ankara (MVA) in different mouse models, comparing lethal infections with VACV strain Western Reserve (VACV-WR) or ectromelia virus (ECTV).


RESULTS
In contrast to VACV-WR challenge, we found extended incubation periods after ECTV challenge, allowing successful therapeutic immunization with VACV-Lister and MVA when applied 2-3 days after exposure. Rapid protection from respiratory tract ECTV infection was significantly affected by vaccine dose and was associated with occurrence of poxvirus-specific antibodies. Vaccinations in type I interferon receptor-deficient mice were protective, whereas recombination activating gene 1-deficient mice lacking mature T and B cells failed to mount immunity after short-term vaccination, confirming an essential role of adaptive immune responses.


CONCLUSIONS
ECTV infection in mice models the course of human smallpox. Our data provide evidence to substantiate historical data on the usefulness of postexposure vaccination with conventional VACV and the new candidate MVA to protect against fatal orthopoxvirus infections.
Paran
Nir
N
Israel Institute for Biological Research, Ness-Ziona, Israel.
Suezer
Yasemin
Y
Lustig
Shlomo
S
Israely
Tomer
T
Schwantes
Astrid
A
Melamed
Sharon
S
Katz
Lior
L
Preuss
Thomas
T
Hanschmann
Kay-Martin
KM
Kalinke
Ulrich
U
Erez
Noam
N
Levin
Reuven
R
Velan
Baruch
B
Löwer
Johannes
J
Shafferman
Avigdor
A
Sutter
Gerd
G
D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D004195:Disease Models, Animal; D018450:Disease Progression; D004781:Environmental Exposure; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D012141:Respiratory Tract Infections / Q000276:immunology / Q000821:virology; D012899:Smallpox / Q000276:immunology* / Q000503:physiopathology / Q000517:prevention & control; D012900:Smallpox Vaccine / Q000235:genetics / Q000276:immunology / Q000627:therapeutic use*; D014616:Vaccinia virus / Q000145:classification / Q000276:immunology*; D014709:Vero Cells; D019562:Viral Load
D012900:Smallpox Vaccine