Novel viruses: Update on the significance of papillomavirus infections in cats

Abstract

Practical relevance: Prior to 1990 papillomaviruses (PVs) were not recognised to infect or cause disease in domestic cats. Since this time, the use of histology, immunohistochemistry and, more recently, molecular techniques has revealed that PVs almost certainly cause feline viral plaques and Bowenoid in situ carcinomas, oral papillomas and feline sarcoids. In addition, there is increasing evidence that PVs play a significant role in the development of feline cutaneous squamous cell carcinomas, one of the most common skin cancers of cats. Recent studies have also revealed that most cats are asymptomatically infected with PVs. This raises a critical question that is currently unanswered: why do only a small proportion of infected cats develop disease? In the future it may be possible to prevent PV-induced diseases by using a vaccine to prevent PV infection. Alternatively, novel therapies may be developed that prevent PVs from causing clinical disease by stimulating the host immune response. Clinical challenges: A recognition of the skin diseases caused by PVs is important to more accurately predict disease progression. Unfortunately, there are currently no non-surgical treatments that have been proven to be beneficial in cats and clinical management of PV-induced skin disease in cats can be challenging. Global importance: PVs have a worldwide distribution and negatively impact feline health and welfare globally. Audience: This review is aimed at clinicians, especially those who regularly treat cats with skin disease. The review will also be useful to oncologists and researchers who have an interest in how cancer develops in cats. Evidence base: In producing this update the authors have drawn on recently published peer-reviewed literature.

Detection and Genetic Characterization of Viruses Present in Free-Ranging Snow Leopards Using Next-Generation Sequencing

“…Several of the viruses indicated in the present study such as feline herpesvirus 1, feline papillomavirus 2, and RVA could affect the health of snow leopards (37,41,44). The impact that these viruses may have on the health of the snow leopards largely depends on the host immunity, which in turn is modulated by other factors such as availability of prey, suitable habitat, and stress.…”

“…However, the papillomavirus discovered in the present study is more similar to feline papillomavirus type 2 (Figure 3). There is increasing evidence that feline papillomavirus type 2 plays a significant role in the development of skin cancers of domestic cats (44) and could potentially also cause skin cancer among snow leopards.…”

Cutaneous vs. Mucosal Tropism: The Papillomavirus Paradigm Comes to an “and”

“…Studies of feline PVs indicate that the same virus can be associated with development of cancers of the skin and mucosal epithelia. Felis catus PV type 2 (FcaPV-2), originally isolated from and then widely associated with pre-neoplastic and neoplastic skin lesions, is detectable in a subset of feline oral squamous cell carcinoma (FOSCC) samples and FOSCC-derived cell lines, where it is transcriptionally active (Lange et al, 2009 ; Altamura et al, 2018a , 2020 ; Munday et al, 2018 ). Accordingly, molecular studies clearly show that FcaPV-2 E6 and E7 oncogenes display biological properties similar to those of mucosal HR HPV-16 in degrading p53 and pRb tumor suppressor proteins (Altamura et al, 2016 , 2018a ).…”

“…Possible transmission routes between the two anatomical sites have also been hypothesized, such as via skin licking or through the bloodstream carrying viral particles to the epithelium of oral cavity (Altamura et al, 2018b , 2020 ). Of note, other FcaPVs are suspected to infect skin and oral epithelia, such as FcaPV-1, -3, and -4 (Munday and French, 2015 ; Munday et al, 2015 , 2018 ; Mazzei et al, 2018 ; Vascellari et al, 2019 ; Chu et al, 2020 ), however additional experimental data are warranted for any confirmation.…”

Identification of a Novel Papillomavirus Associated with Squamous Cell Carcinoma in a Domestic Cat

“…In domestic cats, five papillomavirus genotypes have been described to date [2]. Felis catus papillomavirus (FcaPV) 1 and FcaPV2 are classified in the Lambdapapillomavirus and Dyothetapapillomavirus genera, respectively.…”