Safety, Immunogenicity of Investigational Zika Vaccine Examined

zika virus vaccine
zika virus vaccine
Volunteer participants received either 1 mg or 2 mg doses of the GLS-5700 vaccine over 12 weeks.
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SAN DIEGO — Results of a phase 1, open-label clinical trial of the investigational GLS-5700 vaccine targeting proteins found in the Zika virus has shown positive safety and immunogenicity results, according to research presented at IDWeek 2017.

Pablo Tebas, MD, FIDSA, of the division of infectious diseases at the University of Pennsylvania Perelman School of Medicine, and colleagues presented data from the ZIKA-001 clinical trial (Study of GLS-5700 in Healthy Volunteers; identifier NCT02809443), examining the safety and immunogenicity of the GLS-5700 synthetic DNA vaccine for Zika virus.

Forty participants (median age: 38; 60% female; 78% white) were divided into 2 groups and received the GLS-5700 vaccine at either 1 mg or 2 mg DNA/dose intradermal injection, followed by electroporation with the CELLECTRA®-3P device (Inovio Pharmaceuticals), at 0, 4, and 12 weeks.

At week 4, 25% and 60% of participants in the 1-mg and 2-mg groups, respectively, had undergone seroconversion. At week 6, response was 65% and 84%, respectively. By week 14, antibodies had developed in all participants in both groups, and by the end of the vaccination period, the Zika virus was neutralized in more than 60% of participants.

Local minor adverse effects included injection site pain, swelling, redness, and itching. Systemic adverse events were rare and included headache, myalgia, upper respiratory infection, fatigue, malaise, and nausea.

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Following the vaccination period, researchers evaluated the protective efficacy of the vaccine-generated antibodies using an IFNAR-/- mouse model. Following an intraperitoneal administration of 0.1 mL of either baseline or week 14 serum, the mice received 106 PFUs of ZIKV PR209 isolate. According to the researchers, mice who received week 14 serum survived, suggesting that “the humoral response generated by the vaccine is protective in this model.” 

“Our trial shows for the first time in humans the safety and immunogenicity of an engineered DNA encoding consensus viral protein against [Zika virus],” Dr Tebas and colleagues concluded. “Future studies will evaluate the effectiveness of the vaccine.”

Disclosures: Dr Boyer is an employee and shareholder at Inovio. Dr Park is a board member, CEO, and employee at GeneOne. Dr Trottier is an investigator at the Canadian Institutes of Health Research and has received research grant funding. Drs Maslow and Remigio are employees at GeneOne; Dr Temegio is also a shareholder. Drs Kobinger and Weiner are grant investigators and scientific advisors, and have received grant funding from GeneOne.

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Tebas P, Roberts CC, Muthumani K, et al. Zika-001: safety and immunogenicity of an engineered DNA vaccine against Zika virus infection. Presented at: IDWeek 2017; October 4-8, 2017; San Diego, CA. Poster 839.