(Wikimedia Commons)
23 Aug. 2021. An antiviral nasal spray is shown in tests with lab mice to prevent infection from SARS-CoV-2 viruses and reduce disease-causing cytokines. Findings from challenge tests of the antiviral drug Viraleze, made by Starpharma in Melbourne, Australia, appear in Friday’s issue of the journal Viruses.
Starpharma designs and develops drugs delivered with dendrimers, nanoscale polymer molecules with a branch-like structure. Dendrimers are considered desirable delivery vehicles for their chemical stability, solubility, electrostatic interactions, low toxicity to other cells, and ability to self-assemble. Starpharma uses dendrimers in a gel to prevent and treat bacterial vaginosis, and as an anti-bacterial coating for condoms. The company also markets its dendrimer delivery formulations to other drug makers.
Viraleze is designed by Starpharma as a spray to treat a number of viral diseases that begin in nasal passages. Among those viruses is SARS-CoV-2, the virus responsible for Covid-19 infections. The active ingredient in Viraleze is SPL7013 that the company says inactivates a broad range of respiratory viruses, including SARS-CoV-2, as shown in lab tests reported in September 2020. Starpharma is developing Viraleze both as treatment and a vaccine to prevent infections.
Virtually no viral load for seven days
The journal article reports on tests conducted by Starpharma with Scripps Research Institute in La Jolla, California. The study tested Viraleze with lab mice bred with human angiotensin-converting enzyme 2 or ACE2, receptors, the targets of SARS-CoV-2 viral proteins for gaining entry to cells. The mice were given Viraleze or a placebo sprayed into their noses and windpipes once a day for seven days. One set of these mice were also exposed to SARS-CoV-2 viruses at the same time as the first dose, while another group of mice were given Viraleze an hour before being exposed to SARS-CoV-2.
Researchers tested the mice for SARS-Cov-2 viral load in their blood, an indicator of infection, four and seven days after administration. Both sets of mice receiving Viraleze show virtually no virus in their blood for four days after exposure to SARS-CoV-2. Mice receiving Viraleze an hour before viral exposure continue to show almost no virus in their blood for another three days, while the mice receiving Viraleze at the same time as exposure show a small increase in viral load in that time. Mice receiving the placebo, however, show immediate sharp increases in viral load at both four and seven days after SARS-CoV-2 exposure.
The study team also took swabs from noses and windpipes of the mice, and analyzed tissue samples from their lungs, brains, and livers for signs of virus. Swabs and tissue samples show virtually no evidence of virus in the respiratory systems or organs of mice receiving Viraleze, while high viral concentrations are found in placebo recipients. In addition, researchers find lower levels of cytokine proteins released by the immune system in response to infection in mice receiving Viraleze than placebo recipients. Excessive levels of cytokines are blamed for many of the more severe Covid-19 symptoms.
“These results provide compelling data supporting the utility of a broad-spectrum nasal spray like Viraleze,” says Starpharma CEO Jackie Farley in a company statement, “to reduce exposure to virus, and reduced virus in respiratory tract and other organs, and prevention of pro-inflammatory cytokines, which are important to the pathogenesis of Covid-19.” Farley adds, “One of the potential advantages of Viraleze that these data in this rigorous animal model support, is its ability to significantly reduce viral load in the respiratory tract, which would lower both the transmissibility of the virus to others and severity of disease.”
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