Introduction
Human papillomaviruses (HPV) constitute several genera. The vast
majority of previous research on HPV has focused on the genusAlphapapillomavirus , whose types infect the mucosal epithelium
and are an established cause of anogenital and some oropharyngeal
cancers.1 HPVs of the genus Betapapillomavirusnormally infect the cutaneous epithelium.2Comparatively much less research has been done on the epidemiology of
infections with betapapillomaviruses. However, growing evidence suggests
that betapapillomaviruses may play a role in the development of skin
cancers, and may be associated with the risk of a subset of head and
neck cancers.1,3-5 More research on the incidence,
transmission, and risk factors for betapapillomavirus infection is
warranted.
While betapapillomaviruses were first isolated from the skin and are
widely considered to prefer infecting the cutaneous epithelium, there is
substantial evidence that they are also able to infect the mucosal
epithelium.4,6 The detection of betapapillomaviruses
in oral and genital samples suggests they are able to infect these sites
along with alphapapillomaviruses.7-12 There is
therefore the potential for biological interactions between HPV types of
different genera. While co-detection patterns and the potential for
interactions between HPV types within the alphapapillomavirus genus has
been the topic of substantial previous research,13-16there is scant research on cross-genus co-detection patterns and
interactions. Biological interactions and co-detection patterns between
different HPV types are important to study from a public health
perspective due to the risk of genotype replacement following widespread
implementation of HPV vaccination programs.17 Although
there is currently little evidence that genotype replacement has
occurred for alphapapillomaviruses,18 the potential
for interactions with other HPV genera has not been studied.
We had previously found a fairly high prevalence of betapapillomaviruses
in cervicovaginal samples of the Ludwig-McGill cohort study of HPV
natural history.19 While we examined a number of
putative risk factors, the only variable that was associated with
betapapillomavirus prevalence in univariate analyses was lifetime number
of sex partners; curiously, we found a lower betapapillomavirus
prevalence among women with four or more lifetime sex partners. We also
did not find that alphapapillomaviruses and betapapillomavirus
co-detection patterns deviated significantly from expectations under
independence. However, these analyses were underpowered as we only
tested a restricted number of samples for betapapillomaviruses, and only
looked at prevalent but not incident co-detections.
The objective of the current study was to assess a larger number of
samples of the Ludwig-McGill cohort study than previously tested to i)
examine whether there is evidence of biological interactions between
alphapapillomaviruses and betapapillomaviruses, and ii) assess risk
factors for betapapillomavirus genital prevalence and incidence.