Registration Date 11 May 2020
Revision Date 11 May 2020

Coronavirus Vaccine Candidate


Medicine Pharmaceuticals

COVID-19 vaccine


Coronavirus COVID-19


Maintains strong immunogenicity with potentially improved tolerability Relative to non-replicating vaccinia, horsepox’s replication in human cells provides direct antigen presentation by Class I MHC Horsepox may behave differently as a vector, in part because of its different repertoire of genes that modulate immune responses and host range

Immune system enhancement

Manufacturer's Description

TNX-1800 is based on Tonix’s proprietary horsepox vaccine platform that designed to express SARS-CoV-2 Spike protein. It is believed that horsepox has the potential to serve as a vector for vaccines to protect against other infectious agents. The new research collaboration will develop and test a potential horsepox vaccine that expresses protein from the virus that causes COVID-19 to protect against the disease. The partnership will develop the three vaccine candidates, named TNX-1810, TNX-1820 and TNX-1830, which are based on the horsepox vector platform and designed to express various SARS-CoV-2 antigens. Orthopoxviruses like horsepox induce strong innate and adaptive immunity and long-lasting T-cell immunity. They have designed TNX-1810, TNX-1820 and TNX-1830 to express and induce immunity to SARS-CoV-2 proteins that are different from Spike.

TNX-801 is a live virus vaccine based on synthesized horsepox. TNX-1800 is a modified horsepox virus that is designed to express a protein from the virus that causes COVID-19, which is known as SARS-CoV-2. Molecular analysis suggests that TNX-801 has relatively “complete” left and right inverted terminal repeats (ITRs) while different vaccinia isolates have a variety of deletions in the left and right ITRs. Therefore, TNX-801 has additional genes, relative to vaccinia vaccines, that may play roles in host immune interactions and one or more of such proteins may serve as antigens for protective immunity. Molecular analysis also shows that horsepox is closer than modern vaccines in DNA sequence to the vaccine discovered and disseminated by Dr. Edward Jenner. No new gene elements were added to the natural isolate and the small plaque size in culture appears identical to the U.S. Centers for Disease Control publication of the natural isolate5. Relative to vaccinia, horsepox has substantially decreased virulence in mice. TNX-801 vaccinated macaques showed no overt clinical signs after monkeypox challenge.

In the preclinical evaluation/regulatory stage