Detection and differentiation of Aino and Akabane Simbu serogroup bunyaviruses by nested polymerase chain reaction

Reverse transcription-polymerase chain reaction (RT-PCR) and nested PCR were developed to detect and differentiate Aino (AINO) and Akabane (AKA) virus S RNA. Two pairs of AINO- and AKA-specific primers for nested PCR were synthesized and examined for their capacity to amplify PCR products using 7 Simbu serogroup viruses isolated in Japan and Australia. RT- and nested PCR using AKA-specific primers amplified cDNA from Tinaroo virus RNA as well as homologous RNA. Nested PCR products were differentiated by Hph I and Bst EII digestion. Peaton (PEA) virus S cDNA was also amplified using AINO- specific primers. The nested PCR products of PEA virus were not digested by 3 restriction enzymes (Ava II, Eco RI and Hae II), whereras those of AINO virus were digested as expected. Using this technique, AINO and AKA viruses were detected at concentrations as low as 10(-3) plaque-forming units (PFU) and 10(-5) PFU, respectively, in a supernatant of virus-infected cells. It was possible to detect AINO and AKA genome from various tissues of experimentally infected mice, and also the AKA nested PCR products from serum samples from sentinel cattle naturally infected with AKA virus. The present nested PCR appears a simple, rapid and valuable method for diagnosing AINO and AKA infection.