Arthropod transmission of rabbit papillomatosis

Broad surveys of DNA viral diversity obtained through viral metagenomics of mosquitoes

Viruses are the most abundant and diverse genetic entities on Earth; however, broad surveys of viral diversity are hindered by the lack of a universal assay for viruses and the inability to sample a sufficient number of individual hosts. This study utilized vector-enabled metagenomics (VEM) to provide a snapshot of the diversity of DNA viruses present in three mosquito samples from San Diego, California. The majority of the sequences were novel, suggesting that the viral community in mosquitoes, as well as the animal and plant hosts they feed on, is highly diverse and largely uncharacterized. Each mosquito sample contained a distinct viral community. The mosquito viromes contained sequences related to a broad range of animal, plant, insect and bacterial viruses. Animal viruses identified included anelloviruses, circoviruses, herpesviruses, poxviruses, and papillomaviruses, which mosquitoes may have obtained from vertebrate hosts during blood feeding. Notably, sequences related to human papillomaviruses were identified in one of the mosquito samples. Sequences similar to plant viruses were identified in all mosquito viromes, which were potentially acquired through feeding on plant nectar. Numerous bacteriophages and insect viruses were also detected, including a novel densovirus likely infecting Culex erythrothorax. Through sampling insect vectors, VEM enables broad survey of viral diversity and has significantly increased our knowledge of the DNA viruses present in mosquitoes.

Viral diseases of the rabbit

Viral disease in the rabbit is encountered infrequently by the clinical practitioner; however, several viral diseases were reported to occur in this species. Viral diseases that are described in the rabbit primarily may affect the integument, gastrointestinal tract or, central nervous system or maybe multi-systemic in nature. Rabbit viral diseases range from oral papillomatosis, with benign clinical signs, to rabbit hemorrhagic disease and myxomatosis, which may result in significant clinical disease and mortality. The wild rabbit may serve as a reservoir for disease transmission for many of these viral agents. In general, treatment of viral disease in the rabbit is supportive in nature.

The role of dipterous insects in the mechanical transmission of animal viruses

Animals viruses may be transmitted by arthropods in two ways, either biologically or mechanically. Many different species of Diptera are implicated in mechanical transmission, but haematophagous species are the most important. The insects become contaminated with virus during normal feeding behaviour, and virus persists on their mouthparts or body until the next feed. Some viruses are inactivated rapidly on mouthparts, whereas others survive for many days or weeks, prolonging the potential period of transmission. Some viruses produce high titres in the skin of the infected vertebrate host, which facilitates transmission, whereas other viruses are transmitted even during relatively low levels of viraemia. Mechanical transmission by arthropods is important in the epidemiology of many animal diseases, and may be the major mode of horizontal transmission. In other instances vector spread is merely incidental.