Human-to-Human Transmission of Mpox Clade Ia: New Findings and Implications

Human-to-Human Transmission of Mpox Clade Ia: New Findings and Implications

Sub : Sci

Sec : Health

Why in News

• Recent research has revealed evidence that Clade Ia of the mpox virus has evolved to spread through human-to-human transmission, a shift from the historically limited animal-to-human transmissions associated with this clade. This development raises concerns regarding the virus’s adaptability and the impact of human immune responses on its mutation patterns.

What is Mpox?

• Mpox is a viral zoonotic disease caused by the monkeypox virus which was first recorded in humans in 1970 in the Democratic Republic of the Congo (DRC).
• Mpox can be transmitted to humans through physical contact with someone who is infectious, with contaminated materials, or with infected animals.
• There are no specific treatments for Mpox virus infection.
• In 2022, the disease was declared a global emergency after it spread to some 70 countries. The emergency was withdrawn in 2023.

Mpox Clades: The mpox virus has two main clades: I and II, further divided into subclades Ia, Ib, IIa, and IIb.

Characteristics of Each Clade:

• Clade I: Known for severe effects in animal models; contains subclade Ia (oldest variant) and subclade Ib, recently responsible for central African infections.
• Clade IIb: Identified as the primary clade behind the 2022 global outbreak and still prevalent in parts of Africa.

Focus on Clade Ia: Traditionally, Clade Ia has caused only sporadic animal-to-human infections, mostly among children, with no confirmed human-to-human spread until now.

Role of the APOBEC Protein in Viral Mutation:

• Researchers identified an increase in specific mutations within the mpox virus linked to APOBEC, a family of proteins in the human immune system.
• Mutation Process: APOBEC proteins induce changes in viral DNA by converting cytosine to thymine during replication, which can create random mutations harmful to the virus.
• These mutations suggest that human immune responses may drive viral evolution, especially in facilitating new transmission pathways.
• A significant 63% of mutations in Clade Ia were consistent with APOBEC’s activity, supporting the hypothesis that these viruses had adapted to spread between humans.

How Mutations Occur in Viruses:

• Virus mutations occur through changes in their genetic material (DNA or RNA) during replication. As viruses replicate within a host’s cells, enzymes called polymerases create copies of their genetic code. Occasionally, these enzymes make errors, leading to mutations.
• The mutation rate varies by virus type: RNA viruses, like influenza, mutate faster due to the lack of a proofreading mechanism, while DNA viruses mutate more slowly because they have error-correction processes.
• Proofreading Mechanism in DNA Viruses: DNA viruses, such as those in the pox family, possess error-correction processes that reduce the mutation rate, averaging about one error every three years in a circulating strain.