Ruklanthi de Alwis 1 , 2 , ∗ , Esther S. Gan 2 , ∗ , Shiwei Chen 2 , ∗ , Yan Shan Leong 1 , Hwee Cheng Tan 2 , Summer L. Zhang 2 , Clement Yau 2 , Jenny G.H. Low 1 , 2 , 3 , Shirin Kalimuddin 2 , 3 , Daiki Matsuda 4 , Elizabeth C. Allen 4 , Paula Hartman 4 , Jenny Park 4 , Maher Alayyoubi 4 , Hari Bhaskaran 4 , Adrian Dukanovic 4 , Yanjie Bao 4 , Brenda Clemente 4 , Jerel Vega 4 , Scott Roberts 4 , Jose A. Gonzalez 4 , Marciano Sablad 4 , Rodrigo Yelin 4 , Wendy Taylor 4 , Kiyoshi Tachikawa 4 , Suezanne Parker 4 , Priya Karmali 4 , Jared Davis 4 , Sean M. Sullivan 4 , 5 , Steve G. Hughes 4 , Pad Chivukula 4 , Eng Eong Ooi 1 , 2
5 April 2021
A self-transcribing and replicating RNA (STARR TM) based vaccine (LUNAR®-COV19) has been developed to prevent SARS-CoV-2 infection. The vaccine encodes an alphavirus-based replicon and the SARS-CoV-2 full length spike glycoprotein. Translation of the replicon produces a replicase complex that amplifies and prolong SARS-CoV-2 spike glycoprotein expression. A single prime vaccination in mice led to robust antibody responses, with neutralizing antibody titers increasing up to day 60. Activation of cell mediated immunity produced a strong viral antigen specific CD8 + T lymphocyte response. Assaying for intracellular cytokine staining for IFN-γ and IL-4 positive CD4 + T helper lymphocytes as well as anti-spike glycoprotein IgG2a/IgG1 ratios supported a strong Th1 dominant immune response. Finally, single LUNAR-COV19 vaccination at both 2 μg and 10 μg doses completely protected human ACE2 transgenic mice from both mortality and even measurable infection following wild-type SARS-CoV-2 challenge. Our findings collectively suggest the potential of LUNAR-COV19 as a single dose vaccine.
The LUNAR COV-19 SARS-CoV-2 vaccine is a self-replicating RNA based vaccine that increases antigen expression and also duration of expression. This increased antigen expression combined with the self-activation of the innate immune system produces a low single dose vaccine that yields protective immunity against SARS-CoV-2 virus infection.