French Scientists Find That SARS-CoV-2 Can Replicate and Persist in the Brainstem for Lengthy Periods!

Medical News: A New Study Uncovers the Long-term Effects of COVID-19 on the Brain
A groundbreaking study has revealed that the SARS-CoV-2 virus, which causes COVID-19, can persist and actively replicate in the brainstem for extended periods. These findings shed new light on why some individuals experience long-term neurological and psychological symptoms following a COVID-19 infection. The research was conducted by a team of scientists from the Institut Pasteur, Université Paris Cité _France, including experts in neuropathology, virology, and bioinformatics. Their work not only provides conclusive evidence of the virus’ persistence in the brain but also highlights its association with neuropsychiatric symptoms such as anxiety, depression, and memory impairment.


French Scientists Find That SARS-CoV-2 Can Replicate and Persist in the Brainstem for Lengthy Periods

Long COVID: A Growing Concern
The COVID-19 pandemic has significantly impacted global health, but for many, the struggle does not end when the acute phase of the disease is over. Long COVID, also known as Post-Acute Sequelae of SARS-CoV-2 Infection (PASC), refers to a range of symptoms that persist or appear weeks or months after recovery. These symptoms can include fatigue, respiratory problems, and notably, neurological and cognitive issues such as brain fog, anxiety, and depression.

Despite its prevalence, the mechanisms behind long COVID remain poorly understood. This Medical News report delves into a recent study using animal models to investigate how SARS-CoV-2 affects the brain. The research focused on golden hamsters, a species widely used for COVID-19 studies due to their similarity to humans in disease progression.
 
Key Findings: SARS-CoV-2 in the Brainstem
The researchers conducted an 80-day study to monitor the effects of SARS-CoV-2 in golden hamsters. By infecting the animals with the virus, they aimed to observe its presence and long-term effects on the brain. The key findings were both surprising and concerning:
 
-Viral Persistence in the Brainstem: SARS-CoV-2 was detected in the brainstem as early as 4 hours after infection. Even 80 days post-infection, the researchers were able to isolate live, infectious virus particles from the brainstem. This demonstrates that the virus can persist and replicate in the brainstem for a prolonged period.
 
-Neurodegenerative Changes: Infected hamsters exhibited signs of brain damage consistent with neurodegeneration. The brainstem showed overactivation of the immune system, changes in energy metabolism, and disruptions in neurotransmission (the process by which nerve cells communicate).
 
-Neuropsychiatric Symptoms: Behavioral tests revealed significant long-term effects on mental health and cognition. The infected hamsters displayed symptoms of depression, anxiety, and impaired short-term memory, which persisted even after they appeared physically healthy.
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The brainstem plays a critical role in regulating vital functions like breathing, heart rate, and consciousness. It is also closely linked to emotions, behavior, and memory. Damage or infection in this area can therefore lead to severe and lasting neurological consequences.
 
Understanding the Mechanisms
To understand how SARS-CoV-2 causes such long-lasting effects, the researchers analyzed changes in the brainstem at both the molecular and cellular levels. They identified three major mechanisms that contribute to the neurological symptoms:
 
-Inflammation: During the acute phase of infection, the brainstem exhibited a strong inflammatory response. Immune-related genes were activated, leading to swelling and immune cell infiltration. While this immune response is the body’s way of fighting the virus, prolonged inflammation can damage brain tissue.
 
-Disrupted Neurotransmission: Neurotransmitters like dopamine and glutamate, which are essential for brain function, were significantly disrupted. Dopaminergic pathways, involved in mood regulation and motivation, were impaired. Similarly, the glutamatergic system, which supports learning and memory, showed abnormal activity.
 
-Energy Metabolism Issues: The study revealed mitochondrial dysfunction in the brainstem. Mitochondria are the powerhouses of cells, and their impairment can lead to energy shortages, which are common features of neurodegenerative diseases.
 
These mechanisms together create a “neurodegenerative signature” in the brainstem, which can explain the persistent neuropsychiatric symptoms seen in long COVID patients.
 
Behavioral Changes in Long COVID: Evidence from Animal Models
One of the most significant aspects of the study was the assessment of behavior in infected hamsters. Researchers performed several tests to evaluate anxiety, depression, and memory:
 
-Novelty-Suppressed Feeding Test: Infected hamsters displayed anxiety-like behavior, characterized by an increased hesitation to eat in a new environment. This behavior persisted up to 80 days after infection.
 
-Sucrose Splash Test: This test measures grooming behavior, which reflects motivation and self-care. Infected hamsters, particularly females, showed reduced grooming, indicative of depression-like symptoms.
 
-Novel Object Recognition Test: This test assesses short-term memory. Infected hamsters consistently demonstrated impaired recognition memory compared to healthy controls.
 
These findings mirror the experiences of human long COVID patients, many of whom report anxiety, depression, and cognitive difficulties long after recovering from the acute phase of the disease.
 
Implications for Human Health
The study provides crucial insights into how SARS-CoV-2 affects the brain, particularly the brainstem. The findings suggest that persistent viral infection, inflammation, and metabolic changes in the brain may underlie the neurological symptoms of long COVID.
 
While this research was conducted in animals, the results align with observations in human patients. Studies in COVID-19 survivors have detected viral components in the brain, as well as evidence of neuroinflammation and brain volume changes.
Furthermore, the study raises important questions about the long-term risks of SARS-CoV-2 infection. If the virus can persist in the brainstem for months, could it trigger or exacerbate neurodegenerative diseases like Parkinson’s or Alzheimer’s? This possibility warrants further investigation.
 
Conclusion
This study provides compelling evidence that SARS-CoV-2 can persist and replicate in the brainstem for lengthy periods, leading to neurodegenerative changes and persistent neuropsychiatric symptoms. The findings highlight the critical need for long-term monitoring of COVID-19 patients, even those who recover from the acute phase.
 
As researchers continue to investigate the long-term effects of SARS-CoV-2 on the brain, these findings could pave the way for new treatments and interventions to address long COVID’s neurological and psychological impacts. Understanding the virus’ ability to persist in the brainstem is a crucial step toward mitigating its long-term consequences.
 
The study findings were published on a preprint server and are currently being peer reviewed.
https://www.biorxiv.org/content/10.1101/2024.12.16.628627v1
 
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