Applications of gold nanoparticles in virus detection

Draz, Mohamed Shehata; Shafiee, Hadi

Papillomaviridae is a widely diverse virus family that includes hundreds of recognized viruses classified into 16 taxonomically distinct genera designated with specific Greek alphabet letters, from alpha to pi. The first five genera (Alphapapillomavirus, Betapapillomavirus, Gammapapillomavirus, Mupapillomavirus and Nupapillomavirus) include the human papillomaviruses, while the remaining genera specifically include other mammalian and avian papillomaviruses [189, 190] . Papillomaviruses are spherical, nonenveloped DNA viruses 40-55 nm in size. Their genome consists of a single molecule of circular, supercoiled, dsDNA 5.3-8 kbp in size and encodes 6 early expressed (E) and 2 late (L) expressed proteins, in addition to a noncoding long control region [189, 191] . HPV infections are the most epidemic sexually transmitted viral infections worldwide [192, 193] . HPVs are highly epitheliotropic pathogens that usually infect the deepest layer of the skin or the genital surfaces. Most HPV infections cause no symptoms and usually self-clear without causing clinical problems, but persistent infections lead to serious clinical complications [194] . This persistence typically depends on the type of HPV causing the infection. Among more than 100 types of HPVs, approximately 40 types infect the mucous membranes and can be either high-or low-risk HPVs. High-risk types, such as HPVs 16, 18, 31, 51 and 52, are usually associated with many cancers of the cervix, vagina, vulva, penis, anus, neck, and head, as well as oropharyngeal cancer, while low-risk types, such as HPVs 6 and 11, are mainly related to anogenital warts and recurrent respiratory papillomatosis [195, 196] . Currently, HPV is considered the most important cancer-causing virus, as it is associated with ~4.8% of all human cancers [197] . Despite this high clinical significance of HPV, there are no available treatments, and vaccination using the bivalent vaccine against HPVs 16 and 18 or the quadrivalent vaccine against HPVs 6, 11, 16, and 18 remains the first and only choice for controlling the global HPV disease burden [198] [199] [200] . In fact, these vaccines are relatively expensive, and their efficacy is very restricted to specific HPV types. Therefore, the development of accurate diagnostic techniques for HPV detection and typing is essential for acquiring surveillance data and initiating appropriate vaccination programs.