Surveillance of influenza A virus in environmental ice and water samples.

摘要

Influenza A virus (IAV) is an important human pathogen. IAV infects humans and also a variety of other warm-blooded animals, including various domestic and wild fowl, many domestic and wild mammals. In wild aquatic birds, IAVs primarily are enteric viruses. IAV may have reached evolutionary stasis in birds. As the primary reservoir of all IAV subtypes, wild aquatic fowl play an important role in the ecology of IAV, by maintaining various subtypes of IAV and continuously transmitting genes and viral strains to other host species. Among wild aquatic birds, transmission of IAV occurs through the "oral-fecal" pathway. Environmental ice is a good reservoir for preserving microorganisms alive for long periods of time. In this study, we hypothesized that environmental ice was a good abiotic reservoir for preserving IAV virions shed by wild birds. IAV H1 gene sequences were detected in ice and water samples collected from northeastern Siberian lakes (Lake Park, Lake Edoma). After cloning and sequencing, 83 unique sequences were derived from a Lake Park ice sample and 1 unique sequence was derived from a Lake Edoma water sample. Phylogenetic analysis indicated that the sequences were heterogenous. The sequences shared similarities to IAVs isolated from humans in the 1930s in Europe and in the 1960s in Japan. Through this study, a procedure for developing high sensitivity PCR-based methods for virological surveillance of IAV was established. Although no evidence on the viability of the IAV contained in environmental ice and water was obtained, our results indicated that IAV could be preserved alive in the lake ice. This is supported by the fact that IAV RNA fragments of more than 600 bp were found in the ice. Therefore, environmental ice might act as the abiotic reservoir for infectious IAV, and possibly many other waterborne viruses.