Adjuvant-enhanced antibody responses to recombinant proteins correlates with protection of mice and monkeys to orthopoxvirus challenges

Abstract

Recombinant proteins are being evaluated as smallpox and monkeypox vaccines because of their perceived safety compared to live vaccinia virus. Previously, we demonstrated that three or more injections of a Ribi-type adjuvant with a combination of three proteins from the outer membranes of intracellular (L1 protein) and extracellular (A33 and B5 proteins) forms of vaccinia virus protected mice against a lethal intranasal challenge with vaccinia virus. Here, we compared several adjuvants and found that QS-21 and to a lesser extent alum plus CpG oligodeoxynucleotides accelerated and enhanced neutralizing antibody responses to a mixture of L1 and A33 proteins, provided the highest ratio of IgG2a to IgG1 isotype response, and protected mice against disease and death after only two immunizations three weeks apart. In addition, sera of monkeys immunized with recombinant vaccinia virus proteins and QS-21 neutralized monkeypox virus in vitro and reduced monkeypox virus load, skin lesions, and morbidity compared to the non-immunized group following challenge.

Targeting the vaccinia virus L1 protein to the cell surface enhances production of neutralizing antibodies

“…In previous studies, protection elicited by a protein or DNA vaccine targeting both infectious forms required three or four vaccinations. Recently, it was shown in mice that purified L1 and A33 proteins could elicit a protective antibody response after only two vaccinations if certain adjuvants were used [49]. Here, we demonstrated that delivery of the 4pox antigens, in the absence of adjuvants, could generate protective immune responses after only two vaccinations (Figs.…”

“…We, and others, have shown that vaccines comprised of combinations of immunogens targeting both infectious forms of orthopoxvirus, IMV and EEV, provides superior protection versus targeting only IMV or EEV [19][20][21][22][23][24]41,49,50]. IMV neutralizing antibodies, including those against L1 and A27, neutralize virus in the initial exposure and also can eliminate any IMV released from infected cells that are lysed or EEV that are disrupted.…”

Addition of CpG ODN to recombinant Pseudomonas aeruginosa ExoProtein A conjugates of AMA1 and Pfs25 greatly increases the number of responders

“…Unlike alum, CpG ODN has been shown to be a strongly Th1 biased immunostimulant, showing synergy with alum to promote a mixed Th1 and Th2 pathway. This balancing of antibody responses leads to an increase in total antibody titers [10,[21][22][23][24]. In this study, the comparison of antibody responses between Alhydrogel formulations with and without CPG 7909 was performed with the malarial antigen conjugated to rEPA.…”

Vaccination of BALB/c Mice withEscherichia coli-Expressed Vaccinia Virus Proteins A27L, B5R, and D8L Protects Mice from Lethal Vaccinia Virus Challenge

“…Studies with nonhuman primates or mice have also demonstrated that immunization with baculovirus-expressed recombinant proteins or DNA vaccines composed of different combinations of IMV-and EEVassociated proteins-such as A33R, B5R, and L1R (14,15), A27L, A33R, L1R, and B5R (21), or A27L, B5R, L1R, A33R, and D8L (41)-result in the induction of high levels of neutralizing antibodies and in the protection of mice from lethal challenge with vaccinia virus. In this study, we describe the expression of immunogenic recombinant A27L, D8L, and B5R vaccinia virus proteins by E. coli and demonstrate that subcutaneous immunization of BALB/c mice stimulated high levels of protein-specific and virus-cross-reactive immunoglobulin G (IgG) responses.…”