HLA-G and human papilloma virus infection: Prevalence of Different Human Leukocyte Antigen (HLA) Allelesa and the HLA-G 3ʹ Untranslated Region Single-Nucleotide Polymorphisms Among 271 Heterosexual Couples in the Human Papillomavirus Infection and Transmission Among Couples Through Heterosexual Activity (HITCH) Cohort Study