Persistence of Highly Pathogenic Avian Influenza Virus (H5N1) in Soil Samples at Different Temperatures

摘要

Avian Influenza caused by H5N1 is one of the most important zoonotic diseases and is becoming a great threat to poultry industry as well as to humans. Although wild aquatic birds are the main reservoir for avian influenza viruses, the environment plays a critical role for the circulation and persistence of avian influenza virus. Contaminated water and soil may play roles as reservoirs and sources of transmission for avian influenza virus. However, very little is known regarding the persistence of highly pathogenic avian influenza (HPAI) H5N1 viruses in aquatic environments and soil near the water bodies in tropical countries. The aim of this work was to study the persistence of HPAI (H5N1) virus in soil samples at different temperatures and the physicochemical features of the sources. Soil samples were collected from three different lakes and two ponds in Madhya Pradesh, India and two important physico–chemical parameters (soil moisture and soil pH) were estimated for soil samples. HPAI virus (H5N1) isolate (A/Chicken/Manipur/India/59001/07) was spiked in soil samples and incubated at two different temperatures (12oC and 25oC). The samples were processed every 24 hrs for the isolation of virus in 9 – 11 day old chicken embryos and for detection of viral RNA by carrying out Real Time Reverse Transcriptase PCR (qRT–PCR). Mean persistence of HPAI virus in soil samples at 25°C and 12°C were 8 days and 15.4 days with ranges from 1–18 days and 5 to 29 days, respectively. Mean persistence of viral RNA in soil samples at 25°C and 12°C was 9.6 days and 16.6 days, respectively. HPAI virus (H5N1) persisted longer at 12°C as compare to 25°C indicating a strong negative correlation between the survivability of the virus and temperature. Soil pH showed a strong positive correlation at both the temperatures and moisture content showed strong negative and moderate negative correlation on viral persistence at 12°C and 25°C, respectively The study gives insights into the various physicochemical factors involved in the persistence of avian influenza virus in soil and water and should play an important role in formulating avian influenza control strategies