Potential Zika Vaccine: Encapsulated Nanocomplex Promotes Both T(H)1/T(H)2 Responses in Mice

The concept of vaccination originated from the discovery that cowpox inoculation can prevent infection from the smallpox virus. Subsequent studies have addressed the roles of lymphocytes in induction, education, and memory of host immunity targeting foreign antigens. However, antigens alone stimulate poor immunogenicity, requiring an immunological adjuvant. Common adjuvants include inactivated toxins from bacteria or aluminium hydroxide/phosphate. Although several new adjuvants are being developed, polarized immunity and safety are still of concern. To address these limitations, in the present study, two biodegradable polymers are utilized, chitosan and gamma-polyglutamic acid (gamma-PGA), to encapsulate inactivated Zika virus (iZV) as a nanocomplex (iZV-NC) vaccine by the electro-kinetic approach. iZV-NC vaccine elicited both anti-ZV IgG1/2a antibodies, correcting to T helper (T-H) 2/1 responses in BALB/c mice. Further, these antibodies have the ability to neutralize ZV infection. Additionally, CD4/8 T cells are shown to be activated by ex vivo treatment of iZV, showing established immunity against ZV. Taken together, these results suggest that iZV-NC can produce balanced T(H)1/2 responses compared to the aluminum adjuvant, thereby providing novel insights into the immune mechanism through which NC acts against infectious diseases in humans.