On 30 December 2019, at 7 pm, the mysterious patient samples arrived at the Wuhan Institute of Virology. Shi Zhengli was at a conference in Shanghai at that time. Her phone rang; it was her boss, the director of the institute. Drop whatever you are doing, and come right now, said the director. Shi apologized to the audience and walked out of the conference. At the Shanghai railway station she hopped on to the next train to Wuhan. On the train, she wondered if the municipal authorities had erred. Shi had never expected to find coronavirus in Wuhan, in central China, in the city where China’s best labs for virus research were located.
*****
Shi was barely forty years old when in 2004, she first
joined an international team to visit bat colonies in caves. The bat caves were
near Nanning, the capital of Guangxi. With the sunny and breezy weather of
spring, Shi felt it was a holiday trip. Her first cave was large, made of
splendid limestone columns. Milky white stalactites hung from the ceilings,
glowing with moisture. It was spellbinding, Shi recalls.
But she soon learnt most bats settle in deep, narrow
caves on steep terrain. Guided by local villagers, Shi and her colleagues hiked
for hours, and then crawled in the caves on their stomachs. These shy, flying creatures
can be elusive. After exploring thirty caves, Shi saw only a handful of bats.
That expedition was to find the villain of SARS, the
first big epidemic of the new millennium. It was the first emergence of a
lethal coronavirus with pandemic potential. Shi Zhengli, a genetics graduate
from Wuhan, with a PhD from France, was an early recruit for the expedition.
The SARS virus had jumped from civets to humans, but
it wasn’t known how the civets got it. In Australia’s 1994 Hendra virus
infections, contagion had spread from horses to humans, in Malaysia’s 1998
Nipah outbreak, from pigs. In both cases, it was later discovered that the
pathogens had originated in fruit-eating bats. Horses and pigs were merely the
intermediaries. Would that be the same this time? That was what Shi Zhengli
wanted to find out.
*****
During the virus hunting months of 2004, whenever Shi’s
team identified a bat cave, it would put a net at the entrance before dusk.
When the nocturnal creature tried to leave the cave for food, it was trapped. The
researchers took its blood, saliva samples; fecal swabs, usually late in the
night. After a quick nap, they returned to the cave to collect urine and fecal
pellets in the morning.
Cave after cave, night after night, this yucky
exercise continued for eight months. And not a trace of coronaviruses in a
single bat. Maybe bats have nothing to do with SARS, thought Shi. But then,
another research group gave them a diagnostic kit for testing SARS antibodies.
(Now even lay people are well familiar with the distinction between a virus
test and an antibody test).
Shi tried the antibody test. Quickly she found three
horseshoe bats with SARS antibodies. Shi’s team realised that coronavirus in
bats was short-term and seasonal, but the antibodies could last from weeks to
years. Shi began roaming mountains, visiting caves around China. The
researchers identified one spot: Shitou
cave, near Kunming, the capital of Yunnan. The team conducted intense round-the-year
sampling in this cave over the next five consecutive years.
****
The hard work paid off. Shi’s team discovered hundreds
of genetically diverse bat-borne coronaviruses. Constant mixing of different
viruses creates a great opportunity for dangerous new pathogens to emerge. It
was not necessary to be a wildlife trader to get infected. In 2015 Shi
collected blood samples from 200 villagers near the Shitou cave. Six of them
had antibodies against bat-coronaviruses. They had never handled wildlife, but seen
bats flying in the village.
*****
In December 2018, professor Shi and her associates
published two comprehensive scientific reviews. In them, Shi warned of the risk
of future outbreaks of bat-borne coronaviruses.
(The story of China’s batwoman will continue tomorrow).
Ravi
Fascinating
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