Evaluation of synthetic infection-enhancing lipopeptides as adjuvants for a live-attenuated canine distemper virus vaccine administered intra-nasally to ferrets.
BACKGROUND
Inactivated paramyxovirus vaccines have been associated with hypersensitivity responses upon challenge infection. For measles and canine distemper virus (CDV) safe and effective live-attenuated virus vaccines are available, but for human respiratory syncytial virus and human metapneumovirus development of such vaccines has proven difficult. We recently identified three synthetic bacterial lipopeptides that enhance paramyxovirus infections in vitro, and hypothesized these could be used as adjuvants to promote immune responses induced by live-attenuated paramyxovirus vaccines.


METHODS
Here, we tested this hypothesis using a CDV vaccination and challenge model in ferrets. Three groups of six animals were intra-nasally vaccinated with recombinant (r) CDV(5804P)L(CCEGFPC) in the presence or absence of the infection-enhancing lipopeptides Pam3CSK4 or PHCSK4. The recombinant CDV vaccine virus had previously been described to be over-attenuated in ferrets. A group of six animals was mock-vaccinated as control. Six weeks after vaccination all animals were challenged with a lethal dose of rCDV strain Snyder-Hill expressing the red fluorescent protein dTomato.


RESULTS
Unexpectedly, intra-nasal vaccination of ferrets with rCDV(5804P)L(CCEGFPC) in the absence of lipopeptides resulted in good immune responses and protection against lethal challenge infection. However, in animals vaccinated with lipopeptide-adjuvanted virus significantly higher vaccine virus loads were detected in nasopharyngeal lavages and peripheral blood mononuclear cells. In addition, these animals developed significantly higher CDV neutralizing antibody titers compared to animals vaccinated with non-adjuvanted vaccine.


CONCLUSIONS
This study demonstrates that the synthetic cationic lipopeptides Pam3CSK4 and PHCSK4 not only enhance paramyxovirus infection in vitro, but also in vivo. Given the observed enhancement of immunogenicity their potential as adjuvants for other live-attenuated paramyxovirus vaccines should be considered.
Department of Virology, Erasmus MC, University Medical Center, P.O. Box 2040, 3000 CA Rotterdam, The Netherlands.
D Tien
DT
Nguyen
Martin
M
Ludlow
Geert
G
van Amerongen
Rory D
RD
de Vries
Selma
S
Yüksel
R Joyce
RJ
Verburgh
Albert D M E
AD
Osterhaus
W Paul
WP
Duprex
Rik L
RL
de Swart
D000276:Adjuvants, Immunologic / Q000008:administration & dosage*; D000281:Administration, Intranasal; D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000097:blood / Q000276:immunology; D002522:Chlorocebus aethiops; D004216:Distemper / Q000276:immunology / Q000517:prevention & control*; D004217:Distemper Virus, Canine / Q000276:immunology / Q000472:pathogenicity; D004353:Drug Evaluation, Preclinical; D005260:Female; D005289:Ferrets / Q000276:immunology* / Q000821:virology; D055666:Lipopeptides / Q000008:administration & dosage*; D008214:Lymphocytes / Q000276:immunology / Q000821:virology; D009500:Neutralization Tests / Q000379:methods; D014162:Transfection; D014613:Vaccines, Attenuated / Q000008:administration & dosage / Q000276:immunology; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology; D014709:Vero Cells; D019562:Viral Load; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*
D000276:Adjuvants, Immunologic; D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D055666:Lipopeptides; C508075:Pam(3)CSK(4) peptide; D014613:Vaccines, Attenuated; D014614:Vaccines, Synthetic; D014765:Viral Vaccines