• Human Papillomavirus 11 (HPV 11) is a prevalent member of the HPV family, contributing to the global burden of HPV infections, mainly among women. Worldwide, an estimated 291 million HPV-positive women were reported in 2007, making it the most common sexually transmitted infection in the United States. HPV exhibits high transmissibility, with peak incidence occurring soon after the onset of sexual activity. Despite its widespread occurrence, HPV 11 is classified as a low-risk type, primarily associated with benign conditions.  
• The primary manifestations linked to HPV 11 include anogenital warts, with more than 90% of cases attributed to low-risk HPV types 6 or 11. Additionally, respiratory tract papillomas and low-grade cervical cell abnormalities are benign conditions associated with this low-risk HPV type. While low-risk types like HPV 11 are not directly linked to cancer, they can lead to precancerous changes in cervical cells. It is crucial to distinguish between low-risk types, like HPV 11, and high-risk or oncogenic HPV types that play a significant role in the development of cervical cancer & other anogenital cancers.  
• The prevalence of HPV infection varies globally, influenced by factors such as region, population group, and specific HPV types. Developing countries bear a substantial burden, accounting for about 85% of HPV infections and 88% of deaths due to cervical cancer. HPV 16, often associated with high-risk types, is responsible for 50% of cervical cancers worldwide.  

• Kingdom: Virus  
• Phylum: Cossaviricota  
• Class: Papovaviricetes  
• Order: Zurhausenvirales  
• Family: Papillomaviridae  
• Genus: Alphapapillomavirus  
• Species: Human papillomavirus 11 
•  Human Papillomavirus 11 (HPV 11) possesses distinctive structural characteristics. As a small, non-enveloped DNA virus, it maintains a diameter of approximately 52-55 nanometers.  
• The virus displays icosahedral symmetry, signifying a regular polyhedral shape featuring 20 triangular faces. Comprising the outer protein shell or capsid are 72 pentameric capsomers, with each capsomer housing five copies of the L1 protein (Late 1). This protein capsid encapsulates the circular, double-stranded viral genome of HPV 11, measuring around 8 kb. 
• The viral genome of HPV 11 plays a crucial role and encodes various proteins, delineating its structural and functional components. Six early proteins (E4, E2, E1, E5, E7, E6) participate in virus replication and regulatory functions. Additionally, HPV 11 synthesizes two late proteins (L1 and L2), which serve as the structural proteins of the virus.  

• Human Papillomavirus 11 (HPV 11) displays a remarkable global sequence similarity, lacking geographically specific variants. The L1 protein, a key structural component, constitutes the capsid, forming the outer protein shell of the virus.
• This highly conserved protein assembles into 72 five-fold capsomers, resembling HPV virus-like particles (VLPs). In the development of HPV vaccines, the purified L1 protein is utilized to create empty viral shells, which are immunogenic and prompt the generation of specific neutralizing antibodies. These VLPs serve as the foundation for prophylactic HPV vaccines, introduced in 2006, contributing to global efforts to prevent HPV infections and associated diseases. 

• The transmission of Human Papillomavirus 11 (HPV 11) primarily occurs through intimate, skin-to-skin contact, with the most common modes being vaginal, penile, anal, or oral sex. Infection takes place at the basal epithelium. Despite the high incidence of HPV infection, the majority of cases resolve spontaneously within a year or two. However, a small proportion of individuals experience persistent infection, which represents a crucial risk factor for the development of cervical cancer.  
• Persistent infection with high-risk HPV types, including those associated with cervical cancer, involves mechanisms that allow the virus to escape host immune surveillance & delay the resolution of infection. HPV types 6 & and 11 are known for causing genital warts, with more than 90% of anogenital warts cases attributed to these low-risk HPV types. The pathogenesis of HPV is intricately linked to the interaction of viral oncoproteins, specifically E5, E6, and E7, with host cell proteins such as p16, p53, and Rb. These interactions can disrupt the cell cycle and promote tumor progression.  
• In the context of high-risk HPV types, infection is mild but not sufficient for the development of cervical cancer. Despite harboring high-risk HPV, the vast majority of women with HPV infection do not progress to cancer. 

• The mucosal immune system is pivotal in curtailing HPV infection, serving as the primary defense at mucosal surfaces. However, HPV employs various mechanisms to evade host immunity, including inhibiting the antiviral immune response crucial for HPV clearance. Vaccination emerges as a crucial strategy for preventing HPV infection, with quadrivalent vaccines safeguarding against HPV types 6 and 11. 
• The nonavalent vaccine, such as Gardasil 9, extends protection to these types along with high-risk HPV types implicated in a substantial portion of cervical cancers. Cell-mediated immunity, mainly through cytotoxic T cells, crucial in identifying & eliminating HPV-infected cells, preventing the persistent infection. Additionally, the antibody response against the L1 protein of HPV, induced by vaccination, neutralizes the virus, impeding its entry into host cells and enhancing the overall immune response against Human Papillomavirus 11. 

• Human Papillomavirus (HPV) infection, particularly by HPV 11, can manifest in various clinical presentations. Anogenital warts are a common outcome of HPV 11 infection, displaying as flat lesions, tiny stem-like protrusions, or small cauliflower-like bumps. In women, these warts predominantly occur on the vulva but also appear on the anus, on the cervix, or in the vagina. In men, they manifest on the scrotum, penis, or around the anus. Although anogenital warts typically cause minimal discomfort or pain, they may provoke itching or tenderness.  
• Common warts, another clinical manifestation of HPV 11, present as rough, raised bumps, primarily on the fingers and hands. These warts can be aesthetically displeasing and may sometimes be painful, susceptible to injury, or prone to bleeding. Plantar warts, appearing as hard, grainy growths on the heels or balls of the feet, constitute another form of HPV 11 manifestation and can cause discomfort during weight-bearing activities. Flat warts, more diminutive and smoother than their counterparts, manifest as slightly raised, flat-topped lesions. Children commonly experience these warts on the face, while men may encounter warts in the beard area and women on the legs. 
• Furthermore, certain high-risk HPV types, including HPV 11, can lead to cancer. The association between HPV 11 and cancer is particularly evident in cervical cancer, where genital HPV infection can contribute to the development of cancer in the lower uterus part that connects to the vagina (cervix). Other cancers linked to HPV 11 include those affecting the anus, penis, vagina, vulva, and the back of the throat (oropharyngeal). 

Diagnosing Human Papillomavirus 11 involves several diagnostic tests aimed at detecting visible genital warts and identifying abnormalities that may lead to cancer:  

• Visual Inspection: Healthcare providers visually examine the genital area for any visible warts caused by HPV 11. If warts are apparent, this can aid in diagnosis. However, if the warts are not visible, further testing is necessary.

• Vinegar (Acetic Acid) Solution Test: A vinegar solution is applied to the genital areas infected with HPV. This test is beneficial for identifying difficult-to-see flat lesions. The vinegar solution can cause these lesions to turn white, facilitating their detection.

• Pap Test (Pap Smear): A sample of cells is collected from the vagina or cervix and sent for laboratory analysis. Pap tests can reveal abnormalities that may indicate the presence of HPV-related changes leading to cancer.

• DNA Test: Conducted on cells from the cervix, this test recognizes the DNA of high-risk HPV varieties, including those linked to genital cancers. It is recommended for women aged 30 and older, typically in conjunction with the Pap test, to enhance diagnostic accuracy. 

• The most effective measure against HPV 11 is receiving the HPV vaccine. Three types of prophylactic vaccines are available: bivalent, quadrivalent, and nine-valent. These vaccines have demonstrated efficacy in preventing most cases of cervical, vaginal, vulvar, and anal cancers. The nine-valent vaccine offers additional protection against over 90% of precancerous lesions associated with specific HPV types.

• Using condoms and dental dams consistently during vaginal, anal, or oral sex can help reduce HPV transmission. While these measures are not as effective against HPV as they are for some other sexually transmitted infections, practicing safer sex can lower the chances of contracting and spreading HPV.

• Undergoing regular Pap/HPV tests is crucial for early detection & treatment of any abnormalities associated with HPV infections. These tests help identify precancerous changes in cervical cells, allowing timely intervention to prevent the progression of cancer. 

Human Papillomavirus Type 11 – an overview | ScienceDirect Topics 

Human Papillomavirus (HPV) (who.int)