Source: Hindu

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Context

• The mpox family of viruses is known to be able to evade selective evolutionary pressures by duplicating genes or accumulating mutations and expanding its genome or contracting it by deleting or inactivating genes.
• In a recent study, scientists reported the part of the mpox genome where these changes happen.

Details

• Mpox virus, a member of the poxvirus family, exhibits dynamic evolutionary mechanisms, including the use of 'genomic accordions,' to adapt and infect humans.
• Recent research has highlighted the significance of genomic accordions in driving viral evolution and shaping disease outbreaks.

Historical Context

• Poxviruses, including smallpox and mpox, have been significant threats to public health, with smallpox alone causing millions of deaths before its eradication.
• The 2022-2023 outbreak of mpox, previously known as 'monkeypox,' garnered global attention, underscoring the need for understanding the virus's evolutionary dynamics.

Evolutionary Mechanisms

• Mpox virus exhibits genomic plasticity, allowing it to duplicate genes, accumulate mutations, and expand or contract its genome in response to evolutionary pressures.
• This genomic flexibility enables the virus to evade host immune responses, optimize replication efficiency, and enhance transmission dynamics.

Genomic Accordions

• Genomic accordions refer to rhythmic expansions and contractions of the viral genome, characterized by repetitive sequences and variable regions.
• In mpox virus, genomic accordions play a crucial role in modulating viral fitness, pathogenicity, and host range through gene duplications, deletions, and rearrangements.

Recent study

• A study published in April 2024 in Nature Communications identified specific genomic regions, notably 6.4-kb-long sections, as genomic accordions influencing human-to-human transmission and virulence.
• These sections are found to strongly influence the virus’s human-to-human transmissibility and contain variations in genes affecting viral evolution.

Outbreak Dynamics:

• Mpox genomes are classified into distinct clades, with different lineages exhibiting varying degrees of virulence and transmissibility.
• The 2022 outbreak, predominantly associated with clade IIb, highlighted the role of genomic accordions in enhancing human-to-human transmission and global spread.

Outbreak in the DRC:

• A subsequent outbreak in the Democratic Republic of the Congo (DRC) underscored the emergence of a distinct lineage within clade I, exhibiting increased human-to-human transmission and mortality.
• Genomic analysis of virus samples provided insights into the evolutionary origins and transmission dynamics of the outbreak.

Genomic Surveillance:

• Genomic surveillance of mpox virus facilitates early detection, tracking of transmission chains, and implementation of targeted control measures.
• By monitoring genomic changes, researchers and public health authorities can anticipate emerging variants and assess the efficacy of vaccination strategies.

About Mpox

• Mpox, formerly known as monkeypox, is caused by the Monkeypox virus, belonging to the same family as smallpox.
• It presents with a distinctive rash and other symptoms, progressing through stages before healing, distinct from chickenpox.

History:

• Identified in 1958 during monkey outbreaks; exact origin uncertain, likely linked to African rodents and primates.
• First human case recorded in 1970; previously rare outside Central and West Africa.
• Renamed to Mpox in 2022 by WHO to comply with modern naming guidelines.

Virus Types:

• Clade I: Associated with Central Africa, causing more severe illness with mortality rates up to 10% during outbreaks.
• Clade II: Endemic to West Africa, responsible for the global 2022 outbreak, less severe with survival rates over 99.9%.

Transmission:

• Spread through direct contact with infected animals or materials, and close contact with infected individuals.
• Higher risk of severe illness in individuals with weakened immune systems, infants under one year, those with eczema history, and pregnant women.

About Poxvirus

• Poxviruses comprise a family of large, complex DNA viruses known to infect vertebrates and invertebrates, causing a range of diseases.
• They exhibit unique characteristics, including their brick-shaped morphology and ability to replicate solely within the cytoplasm of infected cells.

Classification:

• Poxviruses are classified into two subfamilies: Chordopoxvirinae and Entomopoxvirinae.
• Chordopoxviruses infect vertebrates, while Entomopoxviruses infect insects.

Human Diseases:

• Several poxviruses are known to infect humans, including Variola virus (causing smallpox), Vaccinia virus (used in smallpox vaccine), and Monkeypox virus.
• Variola virus, the causative agent of smallpox, was eradicated through global vaccination efforts, with the last naturally occurring case reported in 1977.
• Monkeypox virus, endemic in Central and West Africa, causes a smallpox-like disease known as mpox.

Clinical Manifestations:

• Poxvirus infections typically present with characteristic skin lesions, including pustules, vesicles, and scabs.
• Symptoms may vary depending on the specific virus and host factors, ranging from mild rash to severe systemic illness.

Transmission:

• Poxviruses are primarily transmitted through direct contact with infected individuals or contaminated materials.
• Some species exhibit zoonotic potential, with animal reservoirs playing a role in transmission dynamics.

History:

• Smallpox, caused by Variola virus, plagued humanity for centuries, resulting in millions of deaths.
• Intensive vaccination campaigns led to the global eradication of smallpox in 1980, marking a significant milestone in public health.

Sources:

CDC, Hindu

PRACTICE QUESTION Q.  Genomic accordions play a pivotal role in the evolution and adaptation of mpox virus, influencing its virulence, transmissibility, and epidemic potential. Discuss. (250 Words)