This Week in Virology

TWiV 1287: Ancient herpesviruses and modern dementia

Jan 11, 2026
Discover the fascinating journey of ancient herpesviruses as hosts trace 2,500 years of betaherpesvirus 6A and 6B diversity. They also delve into how shingles vaccination might affect dementia outcomes, revealing significant reductions in mild cognitive impairment and dementia mortality. Insights reveal sex differences in vaccine effectiveness and the implications for vaccination policies. The episode is filled with intriguing links between ancient DNA, viral evolution, and modern health challenges.
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ANECDOTE

Denmark's Vaccine Schedule Reflects Local Context

  • Alan described Denmark's pared-down childhood vaccine schedule as driven by low disease prevalence and universal healthcare access.
  • He warned against copying another country's schedule without accounting for local epidemiology and health systems.
INSIGHT

Unique Telomeric Integration Explains Ancient Recovery

  • HHV‑6 uniquely integrates into telomeres and can enter the human germline, producing inherited viral genomes in ~0.4–1% of people.
  • These germline integrations allow ancient viral lineages to be recovered from teeth and bones in archaeological samples.
INSIGHT

Modern HHV‑6 Clades Are Historically Continuous

  • Ancient HHV‑6 genomes fit within modern clades, showing continuity between historical and contemporary viral diversity.
  • Germline integrants persist over centuries, meaning some present-day integrated HHV‑6 came from ancestors millennia ago.
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