Reply to Jensen and Kowalik: Consideration of mixed infections is central to understanding HCMV intrahost diversity

Jensen and Kowalik (1) have reported that intrahost variation in human cytomegalovirus (HCMV) approaches levels similar to those of hepatitis C virus, with fast mutation rates mooted as one explanation (2). While we discuss that HCMV mutation rates were postulated as an explanation for high diversity, the focus of our work is on observed inconsistencies in nucleotide diversity between and within patients (3). Jensen and Kowalik did calculate HCMV mutation rates to be similar to mouse CMV but maintained that this could underestimate the true levels (2). In contrast, our study shows that, in the absence of mixed infections, HCMV is no more diverse than other DNA viruses, and considerably less so than chronic … [↵][1]2To whom correspondence may be addressed. Email: j.breuer{at}ucl.ac.uk. [1]: #xref-corresp-1-1