Epidemiology of Acheta domesticus densovirus and cricket iridovirus in China

Abstract:

Acheta domesticus densovirus (AdDV) was first isolated from infected crickets in Switzerland, 1977 and caused several outbreaks in Europe and the United States. Cricket iridovirus (CrIV), first identified in the Netherlands in 1996, caused a high mortality rate, reduced the fertility, and shortened the life span of infected crickets. The house cricket (Acheta domesticus), was originated from south west Asia and introduced into China as food for reptile pets in recent decades. AdDV and CrIV are common pathogenic viruses that infect house crickets. Unveiling the virus epidemics of house crickets becomes increasingly important with the development of the house cricket industry.Objective To understand the epidemic status of AdDV and CrIV in China, so as to lay a theoretical basis for controlling AdDV and CrIV infections in the house cricket industry and developing effective prevention and control measures.Methods Virus-specific PCR was performed to detect pathogens of the crickets reared in farms spanning different regions of China. The pathogens of the infected crickets were further proved by Sanger sequencing. Transmission electron microscopy was employed to observe the virions in different tissue samples (e.g., gut and fat body) of the infected crickets.Results AdDV virions were icosahedral-shaped particles, nearly spherical, without envelope, with a diameter around 20 nm. It formed dense chromatin regions in the nucleus of the host cell, showing typical features of densovirus. CrIV virions were nonenveloped icosahedral-shaped particles with a diameter of 120-140 nm. A large number of CrIV virions formed a lattice-like arrangement in the cytoplasm, which is a typical feature of iridovirus. The virus-specific PCR detected AdDV in crickets collected from all the on-line shops distributed in different regions of China. CrIV was also detected in crickets collected from most (91%) of the on-line shops. The majority (91%) of detected crickets were infected with both AdDV and CrIV.Conclusion For the first time AdDV and CrIV were found to have been widely spread in China.