IMVAMUNE<sup>®</sup> and ACAM2000<sup>®</sup> Provide Different Protection against Disease When Administered Postexposure in an Intranasal Monkeypox Challenge Prairie Dog Model
M. Shannon Keckler,
Johanna S Salzer,
Nishi Patel,
Michael B Townsend,
Yoshinori J Nakazawa,
Jeffrey B Doty,
Nadia F Gallardo-Romero,
Panayampalli S Satheshkumar,
Darin S Carroll,
Kevin L Karem,
Inger K Damon
Affiliations
M. Shannon Keckler
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Johanna S Salzer
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Nishi Patel
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Michael B Townsend
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Yoshinori J Nakazawa
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Jeffrey B Doty
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Nadia F Gallardo-Romero
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Panayampalli S Satheshkumar
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Darin S Carroll
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Kevin L Karem
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
Inger K Damon
Poxvirus and Rabies Branch, Division of High-Consequence Pathogens and Pathology, Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Atlanta, GA 30333, USA
The protection provided by smallpox vaccines when used after exposure to Orthopoxviruses is poorly understood. Postexposu re administration of 1st generation smallpox vaccines was effective during eradication. However, historical epidemiological reports and animal studies on postexposure vaccination are difficult to extrapolate to today’s populations, and 2nd and 3rd generation vaccines, developed after eradication, have not been widely tested in postexposure vaccination scenarios. In addition to concerns about preparedness for a potential malevolent reintroduction of variola virus, humans are becoming increasingly exposed to naturally occurring zoonotic orthopoxviruses and, following these exposures, disease severity is worse in individuals who never received smallpox vaccination. This study investigated whether postexposure vaccination of prairie dogs with 2nd and 3rd generation smallpox vaccines was protective against monkeypox disease in four exposure scenarios. We infected animals with monkeypox virus at doses of 104 pfu (2× LD50) or 106 pfu (170× LD50) and vaccinated the animals with IMVAMUNE® or ACAM2000® either 1 or 3 days after challenge. Our results indicated that postexposure vaccination protected the animals to some degree from the 2× LD50, but not the 170× LD5 challenge. In the 2× LD50 challenge, we also observed that administration of vaccine at 1 day was more effective than administration at 3 days postexposure for IMVAMUNE®, but ACAM2000® was similarly effective at either postexposure vaccination time-point. The effects of postexposure vaccination and correlations with survival of total and neutralizing antibody responses, protein targets, take formation, weight loss, rash burden, and viral DNA are also presented.
