Around half of all children have antibodies to Human B19 erythrovirus by age 15. Most childhood infections are asymptomatic or cause malaise and fever. Adult infections, however, can result in a form of arthritis. The virus infects red blood cell precursors in the bone marrow, reducing blood cell production. This can severely affect people with anemia, as well as developing fetuses in pregnant women.
Like other parvoviruses (left), B19's viral genome consists of a single strand of DNA that needs to replicate via a double-stranded intermediate. But despite being DNA, B19 evolves rapidly: in a Journal of Virology paper, Laura Shackelton and Eddie Holmes report evolutionary rates more characteristic of RNA viruses than DNA viruses. These rates (around 10-4 nucleotide substitutions per site per year) are similar to those which they previously found in canine and feline parvoviruses — sugggesting that rapid evolution may be typical of this family of viruses.
These findings indicate that the difference between DNA and RNA viruses is less simple than once thought. Unlike some other DNA viruses, parvoviruses rely entirely on host "machinery" to replicate their genomes. This rapid evolution suggests that host proteins may not replicate single-stranded viral DNA as accurately as they do their own genetic material.
Written By: Laura A. Shackelton& Edward C. Holmes
Journal: 80: 3666-3669
Journal Reference: 80: 3666-3669
Paper Id: 10.1128/JVI.80.7.3666-3669.2006