New Delhi: Scientists at the Indian Institute of Technology
(IIT), Jodhpur, have explored the neuro-invasive nature of novel coronavirus
highlighting that loss of smell and taste of infected patients makes the entire
Central Nervous System (CNS) and underlying structures in the brain more prone
to the viral infection with devastating effects.
Dr. Surajit Ghosh and his team have pointed out that
SARS-CoV-2 is known to interact with a specific human receptor ‘hACE2’ (human
angiotensin-converting enzyme-2) which also happens to be entry point of the
virus and has an almost ubiquitous presence in most human organs ranging from
lung parenchyma to nasal mucosa. The brain is also known to express this
“The loss of smell or taste points to the fact that nose and
mouth are key entry points of the virus, which then may slowly make way to the
olfactory bulb using neurons of the olfactory mucosa. The olfactory bulb
located in the fore-brain is the structure that is chiefly responsible for the
sense of smell. This explains the loss of smell associated with many
asymptomatic carriers of Covid-19 and may expose the CNS to the viral
infection,” the study said.
The paper accepted in ACS Chemical Neuroscience and supported
by Science & Engineering Research Board (SERB), a statutory body under the
Department of Science & Technology (DST), has suggested probable
therapeutic strategies on the basis of understanding neurological
manifestations of Covid-19.
The paper recounts a recently conducted study on the brain
scans (CT and MRI) of a patient infected by Covid-19 virus that shows a rare
encephalopathy called ANE, which leads to brain dysfunction with seizures and mental
disorientation. It indicates that in the presence of human ACE2 receptors in
CNS, the brain may be infected by the virus through the olfactory bulbs and
also through other peripheral nerve terminals or simply blood circulation and
may breach the blood-brain barrier to innervate and attack CNS. The scientists
said it may completely destroy medulla oblongata of the hind-brain, which
regulates breathing, heart, and blood vessel function.
The study rings warning bells to asymptomatic carriers of
Covid-19 with anosmia (loss of smell) and ageusia (loss of taste) to
self-quarantine themselves as soon as they feel these symptoms and consult
specialized nephrologists before they turn into carriers. It also suggests
brain autopsies of Covid-19 infected patients and analysis of their
"The pathway of infection of SARS-CoV-2 and its impact
on various organs is an important area that would also help with the future
rational approaches for therapy. The neuro-invasive nature of the virus and its
effects on the senses of smell and taste are thus interesting and useful areas
of investigation,” said Professor Ashutosh Sharma, Secretary, DST.
The study found activities like smoking could increase the chances of contracting Covid-19 infection, attributing this to interactions and co-expression of the hACE2 receptor and the nicotinic receptor, which is stimulated on smoking.