Vaccine. 2013 Aug 12;31(36):3718-25. doi: 10.1016/j.vaccine.2013.05.086.

A recombinant measles vaccine expressing chikungunya virus-like particles is strongly immunogenic and protects mice from lethal challenge with chikungunya virus.

Brandler S, Ruffié C, Combredet C, Brault JB, Najburg V, Prevost MC, Habel A, Tauber E, Desprès P, Tangy F.

Unité de Génomique Virale et Vaccination, Institut Pasteur, CNRS URA 3015, 28 rue du Dr. Roux, 75724 Paris Cedex 15, France. samantha.brandler@pasteur.fr

 

Abstract

Chikungunya virus (CHIKV), a mosquito-transmitted alphavirus, recently reemerged in the Indian Ocean, India and Southeast Asia, causing millions of cases of severe polyarthralgia. The virus is currently spreading in the Caribbean islands close to the U.S. therefore the virus may reach the U.S., perhaps via Florida.No specific treatment to prevent disease or vaccine to limit epidemics is currently available. Here we describe a recombinant live-attenuated measles vaccine (MV) expressing CHIKV virus-like particles (VLPs) comprising capsid and envelope structural proteins from the recent CHIKV strain La Reunion. Immunization of mice susceptible to measles virus induced high titers of CHIKV antibodies that neutralized several primary isolates. Specific cellular immune responses were also elicited. A single immunization with this vaccine candidate protected all mice from a lethal CHIKV challenge, and passive transfer of immune sera conferred protection to naïve mice. Measles vaccine is one of the safest and most effective human vaccines. A recombinant MV-CHIKV virus could make a safe and effective vaccine against chikungunya that deserves to be further tested in human trials.

In this work we demonstrate the potential of a recombinant measles-CHIKV virus to make an effective CHIKV vaccine candidate. Cells infected by this live vector expressed high levels of CHIKV antigens and secreted VLPs with typical alphavirus morphology (Figure 1). Evaluated in CD46-IFNAR mice susceptible to MV infection, the vaccine virus induced high levels of CHIKV neutralizing antibodies. All immunized mice were repeatedly protected from lethal challenge with CHIKV, even after a single immunization, demonstrating a strong protective capacity in this experimental model (Figure 2). The vaccine conferred protection against homologous and heterologous CHIKV circulating strains, and passive transfer of immune sera to highly susceptible recipient IFNAR mice conferred protection from lethal CHIKV challenge. Cell-mediated immune response was also elicited that may contribute to protection. Importantly, preexisting immunity to MV did not impair the protective capacity of MV-CHIKV, thus allowing considering using this vaccine not only in naïve infants but also in preimmune adults. Obviously, this experiment performed in transgenic CD46-IFNAR mice should be confirmed in immuno-competent primates.

fig1

Figure 1. (A) Schematic representation of CHIKV C-E3-E2-6k-E1 construct and of recombinant MV vector previously described (Combredet et al; 2003). (B) Replication rate of MV-CHIKV compared with standard MV on Vero cells. (C) Immunofluorescence detection of CHIKV E2 protein in Vero cells infected for 24 h with MV-CHIKV recombinant virus. bottom black-and-white image shows an earlier stage of infection with non-infected negative cells surrounding infected zones. (D) Detection by western blot of CHIKV E2 (left) and Capsid (right) expression in cell lysates (L) and supernatants (SN) of Vero cells infected by MV-CHIKV recombinant virus (cell lysates are 20 times more concentrated than supernatants). CHIKV proteins were probed with specific Mabs. (E) Electron microscopy analysis of CHIKV VLPs secreted in the supernatant of Vero cells infected by MV-CHIKV recombinant virus at MOI 0.1. Scale bars are indicated in each panel. Red arrows indicate the specific arrangement of spikes on particles surface and the icosahedral symmetry of the capsid protein inside the particles.

 

fig2

Fig. 2. Protective efficacy of MV-CHIKV recombinant virus. (A) Survival of CD46-IFNAR mice (6 mice/group) immunized twice at one month of interval with different doses of MV-CHIKV then lethally challenged with 100 PFU of CHIKV-06-49 one month after the last immunization. (B) Survival of CD46-IFNAR mice (6 mice/group) immunized with a single dose (105 TCID50) of MV-CHIKV or empty MV then lethally challenged with 100 PFU of CHIKV-06-49 two weeks after. (C) Survival of IFNAR mice (6 mice/group) lethally challenged with 100 PFU of CHIKV-06-49 after passive transfer of pooled sera from CD46-IFNAR mice immunized with 105 TCID50 of MV-CE3E26KE1 recombinant virus. Control mice received a CHIKV HMAF or sera from CD46-IFNAR mice immunized with empty MV. (D) Survival of CD46-IFNAR mice (6 mice/group) immunized with two doses of MV-CHIKV or empty MV (105 TCID50) in the presence or not of anti-MV vector preimmunity, then lethally challenged with 100 PFU of CHIKV-06-49 one month after the last immunization.

 

In conclusion, this strategy combines the safety and immunogenicity advantages of a VLP vaccine produced in vivo from the widely used measles vaccine. This vaccine recently tested in Phase I clinical trial demonstrated both an excellent safety and a strong immunogenicity in healthy volunteers with pre-existing immunity to measles. This work also reveals the capacity of MV to express VLPs from a positive stranded RNA virus, indicating its potential to generate VLPs based vaccines against other arboviruses.

 

Multiselect Ultimate Query Plugin by InoPlugs Web Design Vienna | Webdesign Wien and Juwelier SchönmannMultiselect Ultimate Query Plugin by InoPlugs Web Design Vienna | Webdesign Wien and Juwelier Schönmann