First report of human salivirus/klassevirus in respiratory specimens of a child with fatal adenovirus infection

Adenovirus is a leading cause of respiratory infection in children. Salivirus/klassevirus was first identified as an etiologic agent of gastroenteritis and was never reported in respiratory infection cases. The case being discussed here caught our attention because, although it is a common respiratory infection, it was fatal, while similar cases were mild. In order to find potential causes in the fatal case, we describe the clinical diagnosis and treatment, the sequencing analysis of the salivirus/klassevirus, and the co-infectious adenovirus. Metagenomics sequencing was conducted on the samples from a nasopharyngeal swab of the children with adenovirus infection. Sequences were assembled using IDBA-ud (1.1.1); phylogenetic analysis was performed using MEGA 5.2. RT-PCR and quantitative PCR were performed to verify the existence of the virus in the samples. A nearly full genome of this new virus strain was obtained with 7633 nt encoding a polyprotein of 2331 aa. Meanwhile, it was detected specifically in the nasopharyngeal swab by RT-PCR. Further, homology analysis indicated that the virus has a closer relationship with Salivirus A strain in Shanghai (GU245894). Our study reports the first case of Human salivirus/klassevirus in respiratory specimens of a child with fatal adenovirus infection in Shenzhen, China. The finding and investigation of the virus will provide more useful information for the clinical diagnosis of unexplained lethal infection and expand our knowledge of the new family, salivirus/klassevirus in picornavirus.