Impact of Single- Versus Multiple-Type HPV Infections on Cervical Cytological and Histological Abnormalities: The Dominant Oncogenic Potential of HPV16 Single-Type Infections

<b>Background:</b> Persistent infection with high-risk human papillomavirus (HR-HPV) is the primary cause of cervical intraepithelial neoplasia (CIN) and cervical cancer. While HPV testing has become central to screening programs and the frequency of detecting multiple HPV genotypes has subsequently risen, the clinical relevance of multiple-type (MT) HPV infections remains uncertain. This study aimed to investigate the correlation between HPV infection type and the severity of cervical cytological and histological abnormalities. <b>Methods:</b> This retrospective study analyzed 340 women with dysplasia and 82 with histologically confirmed cervical cancer treated at the University Hospital Cologne between 2016 and 2019. HPV genotyping was performed using a DNA microarray detecting 41 HPV genotypes. Associations between infection patterns and cytological and histological findings were evaluated. <b>Results:</b> Multiple infections accounted for 42% of HPV-positive cases (119 among 284), showing a bimodal age distribution with peaks in patients ≤19 and ≥60 years. HPV16 and HPV18 were most frequently detected in worse than CIN3 lesions (CIN3+), mainly as single-type (ST) infections. Women with ST infections had a significantly higher risk of CIN3+ compared to those with MT infections (<i>p</i> = 0.004). HPV16 ST was significantly associated with CIN3+ compared to other HR-HPV ST (<i>p</i> = 0.046), whereas MT including HPV16 did not increase CIN3+ risk (<i>p</i> = 0.124). Co-infections involving alpha-9 clade types were associated with higher CIN3+ risk, while alpha-7 co-infections did not show an additive effect. Furthermore, coinfections involving two different alpha-9 or -7 were observed infrequently. <b>Conclusions:</b> Single HR-HPV infections are more strongly associated with high-grade cervical lesions than multiple infections, especially when HPV 16 is involved. These findings underscore the dominant oncogenic potential of HPV16 and suggest that intergenotypic interactions in MT infections may mitigate malignant progression.