Genetic diversity of human papillomavirus infections in anogenital warts and cancers

Abstract

Low risk Human Papillomaviruses (LR-HPVs) 6 and 11 are the main causative agents of benign proliferative lesions such genital warts (GWs) and recurrent respiratory papillomatosis (RRP) (Aubin et al. 2008; Ball et al. 2011; Garland et al. 2009; Prétet et al. 2008). High Risk HPV (HR-HPV) 16 is the most oncogenic type and is responsible for invasive cancers (IC) of cervix (ICC), vulva (IVuC), vagina (IVaC), penis (IPeC) and anus (IAnC) (Alemany et al. 2014, 2015, 2016; Larsson et al. 2013; de Sanjose et al. 2010). The well-established connection between HPV16 infection and IC is observed for the most prevalent ICC histological presentations namely squamous cell carcinomas (SCC), adenocarcinomas (ADC) and adenosquamous cell carcinomas (ADSC) (de Sanjose et al. 2010). All these three HPVs (HPV6, HPV11 and HPV16) are the most prevalent in their associated pathological outcomes (Alemany et al. 2014, 2015, 2016; Aubin et al. 2008; Ball et al. 2011; Garland et al. 2009; Larsson et al. 2013; Prétet et al. 2008; de Sanjose et al. 2010). At level of HPV variants, previous studies have addressed differential HPV6 and HPV11 lineage distributions in GWs and RRP, but mainly at a national or regional level (Kocjan et al., 2009). Although without large sample size, some studies describe differential prevalence of HPV variants among distinct pathologies (Danielewski et al. 2013; Jelen et al. 2014). For HPV6, it has been observed a higher presence of HPV6_B1 variants in GWs compared to RRPs (Flores-Díaz et al. 2017b). HPV16 variant distribution has been mainly focused on the uterus cervix and less on other anatomical sites (Cornet et al. 2012; Yamada et al. 1997), what emphasizes the still wanting research of HPV16 viral lineages in other anogenital cancer location (non-cervical cancers). Some studies show that HPV16 variants in anogenital cancers are largely the same regardless of cancer anatomical locations (ICC, IVuC, IVaC, IAnC and IPeC) , showing increased prevalence of HPV16 A1-3 for all IC of squamous nature (de Koning, Quint, and Pirog 2008; Larsson et al. 2013; Ouhoummane et al. 2013; Tornesello et al. 2008; Zuna et al. 2011). HPV16 variants have been widely studied in SCC (Cornet et al. 2012; Zuna et al. 2011), as this histological type remains the most prevalent ICC (Vinh-Hung et al. 2007; Vizcaino et al. 2000). Nonetheless, data available is poorer for other cervical cancer histological presentations such ADC and ADSC. Although few studies had addressed other glandular histologies, they had been restricted to local geographic origin or small populations (Burk et al. 2003; Lizano 2006; Qmichou et al. 2013; Tornesello et al. 2011). Previously described background, shows an increased prevalence of HPV16_A1-3 variants in SCCs (Zuna et al. 2011) while an enhanced presence of HPV16_D in ADCs (Burk et al. 2003; Mirabello et al. 2016; Quint et al. 2010). Regarding HPV16 intratype variability, it has grown the interest of researchers on the T350G E6 polymorphism as data shows an increased oncogenic potential of those variants containing the 350G allele (Grodzki et al. 2006; Jackson et al.

2016; Zehbe et al. 1998, 2001). Finally, most of the data published do not show results regarding age at tumour diagnosis or use different age definitions such age at enrollment (Mirabello et al. 2016). According to the HPV variant context, the works presented in this thesis try to provide all together information about LR-HPV6 and 11 and HR-HPV16 variant diversity among different lesions, cancers and among different geographical regions with a worldwide spectrum, analyzing large number of HPV monoinfected samples, strategy that prevents possible added bias introduced by co-infections or multi-infections. Through these manuscripts we present for the first time the relative contributions of variant differential abundance, geographical origin, cancer anatomical locations and IC histological presentations to the observation of differential prevalence distribution of HPV16 variants. Through our cases data, we show concordant results with previous published works, observing an increased prevalence of HPV6 B1 variants in GWs, of HPV16 A1-3 variants in anogenital cancers of squamous nature and of HPV16 D variants in ADC. We further show determinate geographical structure of HPV16 variants largely based on the dominance of HPV16 A1-3 variants in Europe, the virtually exclusive presence of HPV16 B and C variants in Africa, the increased prevalence of HPV16 A4 variants in Asia and the enrichment of HPV16 D variants in the Americas. For the most oncogenic-related polymorphism, the E6- T350G, we further show different allelic frequencies according to geographical location independently of the anogenital cancer analyzed, revealing an enhanced 350G allele frequency in isolates from Central-South America compared with Europe. Additionally, we confirme the worldwide trend of cervical cancers to be diagnosed significantly earlier than other anogenital cancers and at histological level, we further present that ADC are diagnosed earlier (mid-forties) than SCC (mid-fifties).

According to the previous context, our results complement and may expand those communicated. The current data suggests that the outcome of the virus-host interaction depends on the combination of phylogeny (i.e. the individual genetic background of both virus and patient) and ontogeny (i.e. the differential susceptibility of different tissues) and for HPV16, provide integrating knowledge of variant-specific differential risk that may impact the future screening algorithms, helping to ensure proper early detection of, for example, elusive ADCs. Furthermore, our data emphasizes the necessity of developing deep analyses in HPV variant field. Additionally, the monitoring of initial steps in viral colonization of anogenital mucosas and the follow-up of differential viral persistences according to patient genetic background, may be of remarkable importance. All these research might ultimately provide answers about the extent of the differential fitness of

HPV viral lineages and will help to understand the virus-host interplay for the most oncogenic HPVs. Additionally, in vaccinated women follow-up, tracing HPV variants may need to keep more attention as, although not described any evidence, they may be indeed, a possible causative agent of not expected pathological outsiders.

Descripción de la distribución diferencial de variantes de los virus del Papiloma humano 6 y 11 (VPH6 y VPH11) en sus patologías asociadas: verrugas genitales y papilomatosis respiratória recurrente. Descripción de la distribución diferencial de variantes del virus del Papiloma humano 16 (VPH16) en cánceres anogenitales humanos y en los distintos tipos hisológicos de cancer de cérvix (escamoso, adenoescamoso y adenocarcinoma). Para las variantes de VPH16, se decribe su distribución geográfica a nivel mundial y se cuantifica la contribución relativa de la distinta abundancia de las variantes de VPH16, localización anatómica del cáncer,histología y geografía respecto a la observación diferencial de las variantes de VPH16