The process of nitrate–nitrite circulation from nature into the human body. Courtey of Huang Jianping
COVID-19 waves a spike protein as it roams a host’s body, a hand reaching out to greet cells in a nasty trick. The virus connects to a cell, binding, breaking in and hijacking the molecular machinery to proliferate. Once it happens, via infection or vaccination, the body’s immune system knows how to recognize the foe and can mitigate future attacks via specialized antibodies. Two years since the spike protein was first mapped, humanity knows it is not that straightforward. The spike protein shapeshifts and fools the best defenses, the virus’s genetic makeup morphing to produce more fit variants to attack anew. The mutants result from biological interactions changing and streamlining genetic material, knocking out certain traits and improving others, but might there be another — and potentially global — cause of variants?
Answers may be in the sky and in the sea, according to a new paper made available online ahead of publication in Atmospheric and Oceanic Science Letters. Researchers from Lanzhou University’s Collaborative Innovation Centre for West Ecological Safety are calling for the scientific community to investigate the role of nitric oxide, a molecule known to damage and mutate genetic material, in the COVID-19 variants. Nitric oxide is produced through both biological processes and environmental events, such as lightning and seawater intrusion.
“This study provides a new perspective on the possible mechanism of new coronavirus variants,” said corresponding author Jianping Huang, a distinguished professor and director of the Collaborative Innovation Centre for West Ecological Safety at Lanzhou University who previously published a climate modeling system used to predict how COVID-19 spreads across the globe. “Researchers have put a great deal of effort into studying the underlying mechanism of mutation from a biological point of view, but the relationship between the environment and mutation has rarely been mentioned.”
Nitric oxide is a free radical — a loose molecule — in the body, a byproduct resulting from cell signaling to maintain cardiovascular and immune systems, among others. In overabundance, however, it stresses cells, damaging and dysregulating biological functions, including mutating genetic material that can help viral conmen further refine their disguises.
While people naturally produce nitric oxide, they can also consume it from the environment. Lightning produces high temperatures that break atmospheric nitrogen into nitrogen oxides, which dissolve in rain and combine with the water to form nitrate that falls to the planet’s surface and becomes fertilizer for plants. Humans eat the plants, including the nitrates, which they eventually break down to nitric oxide. The molecule is also abundant in seawater, which feeds into the groundwater of coastal areas, entering the cycle by watering the plants or animals people consume.
“This connection might partly explain that most new variants were first identified near coastlines,” Huang said, noting that the Alpha, Beta, Gamma, Eta and Delta lineages were all first detected near coasts. Omicron, which had not emerged at the time of the report, was first detected in Botswana and South Africa. While Botswana is landlocked, it shares a border with South Africa, which as an extensive coastline meeting both the Atlantic and Indian oceans. “These areas all experience thunderstorms, including lightning — and many had more frequent lightning strikes prior to the emergence of new variants.”
Huang cautioned that their report is a preliminary investigation and, as such, has limitations. They did not investigate other sources of atmospheric nitrate oxide, such as transportation and industrial activity, and potential connections to COVID-19 variants, which could reveal more information about the environmental influence on viral mutations, Huang said.
“Moreover, lightning and seawater intrusion may not necessarily cause the virus to mutate, but rather help promote the possibility,” Huang said. “Nonetheless, our study highlights a new direction for researcher to elucidate more connections between environmental factors and virus mutations in the future.”
Other contributors include Yingjie Zhao and Danfeng Wang, both with the Collaborative Innovation Centre for West Ecological Safety at Lanzhou University.