Subunit Recombinant Vaccine Protects against Monkeypox

Abstract

The smallpox vaccine Dryvax, a live vaccinia virus (VACV), protects against smallpox and monkeypox, but is contraindicated in immunocompromised individuals. Because Abs to VACV mediate protection, a live virus vaccine could be substituted by a safe subunit protein-based vaccine able to induce a protective Ab response. We immunized rhesus macaques with plasmid DNA encoding the monkeypox orthologs of the VACV L1R, A27L, A33R, and B5R proteins by the intradermal and i.m. routes, either alone or in combination with the equivalent recombinant proteins produced in Escherichia coli. Animals that received only DNA failed to produce high titer Abs, developed innumerable skin lesions after challenge, and died in a manner similar to placebo controls. By contrast, the animals vaccinated with proteins developed moderate to severe disease (20–155 skin lesions) but survived. Importantly, those immunized with DNA and boosted with proteins had mild disease with 15 or fewer lesions that resolved within days. DNA/protein immunization elicited Th responses and binding Ab titers to all four proteins that correlated negatively with the total lesion number. The sera of the immunized macaques recognized a limited number of linear B cell epitopes that are highly conserved among orthopoxviruses. Their identification may guide future efforts to develop simpler, safer, and more effective vaccines for monkeypox and smallpox.

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

“…However, both DNA [16] and protein [11] immunization studies indicated that multicomponent vaccines eliciting antibodies to MV and EV proteins provided better protection against VACV than single component vaccines. In addition, monkeypox virus (MPXV) DNA priming and protein boosting provided better protection in a MPXV model than either alone [17]. Results obtained by passive administration of polyclonal or monoclonal IgGs to A33, B5 and L1 suggested that antibodies are important for the protection achieved by protein vaccines [18,19].…”

“…A33R, and B5R) administered percutaneously with a gene gun [63]. In a recently published study [17], it was reported that a 4-component DNA vaccine composed of MPXV orthologs of the same VACV genes administered intramuscularly did not induce neutralizing antibody or protect monkeys against a MPXV challenge. In contrast, the corresponding recombinant MPXV proteins with alum or CPG ODNs provided partial protection, which was enhanced by prior DNA vaccinations.…”

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

“…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.…”

“…This dose is three times the LD 50 . Subsequently, mice were observed and weighed daily for 14 d. Moribund mice (>30% body weight) were euthanized.…”

“…Mice were vaccinated two times with L1R, tPA-L1R, 4pox, or 4pox (tPA-L1R) and then challenged intranasally with three LD 50 of VACV strain IHD-J. For controls, two groups of mice either unvaccinated or vaccinated with live-virus (Connaught) by tail scarification were also challenged.…”