In action-an early warning system for the detection of unexpected or novel pathogens

Novel Virus Identification through Metagenomics: A Systematic Review

Metagenomic Next Generation Sequencing (mNGS) allows the evaluation of complex microbial communities, avoiding isolation and cultivation of each microbial species, and does not require prior knowledge of the microbial sequences present in the sample. Applications of mNGS include virome characterization, new virus discovery and full-length viral genome reconstruction, either from virus preparations enriched in culture or directly from clinical and environmental specimens. Here, we systematically reviewed studies that describe novel virus identification through mNGS from samples of different origin (plant, animal and environment). Without imposing time limits to the search, 379 publications were identified that met the search parameters. Sample types, geographical origin, enrichment and nucleic acid extraction methods, sequencing platforms, bioinformatic analytical steps and identified viral families were described. The review highlights mNGS as a feasible method for novel virus discovery from samples of different origins, describes which kind of heterogeneous experimental and analytical protocols are currently used and provides useful information such as the different commercial kits used for the purification of nucleic acids and bioinformatics analytical pipelines.

Multiple Novel Mosquito-Borne Zoonotic Viruses Revealed in Pangolin Virome

Swab samples were collected from 34 pangolins in Guangxi Province, China. Metavirome sequencing and bioinformatics approaches were undertaken to determine the abundant viral sequences in the viromes. The results showed that the viral sequences belong to 24 virus taxonomic families. To verify the results, PCR combined with phylogenetic analysis was conducted. Some viral sequences including Japanese encephalitis virus (JEV), Getah virus (GETV), and chikungunya virus (CHIKV) were detected. On the basis of the metavirome analysis, seven segments belonging to JEV were further identified through PCR amplification. Sequence comparison showed that, among seven sequences, JEV-China/P2020E-1 displayed the highest nucleotide (80.6%), with the JEV isolated in South Korea, 1988, and all of which belonging to genotype III. Seven CHIKV sequences were detected, with the highest homology (80.6%) to the Aedes africanus in Côte d’Ivoire, 1993. Moreover, passage from BHK-21 to Vero cells makes the newly isolated CHIKV-China/P2020-1 more contagious. In addition, the newly verified GETV sequences shared 86.4% identity with the 1955 GETV isolated from Malaysia. Some sudden and recurrent viruses have also been observed from the virome of pangolin in Guangxi Province, China; hence, dissemination tests will be implemented in the future.

Metagenomic Analysis of Togaviridae in Mosquito Viromes Isolated From Yunnan Province in China Reveals Genes from Chikungunya and Ross River Viruses

We collected 5,500 mosquitoes belonging to six species in three locations in China. Their viromes were tested using metagenomic sequencing and bioinformatic analysis. The affluent viral sequences that were detected and annotated belong to 22 viral taxonomic families. Then, PCR was performed to confirm the results, followed by phylogenetic analysis. Herein, part of mosquito virome was identified, including chikungunya virus (CHIKV), Getah virus (GETV), and Ross river virus (RRV). After metagenomic analysis, seven CHIKV sequences were verified by PCR amplification, among which CHIKV-China/YN2018-1 had the highest homology with the CHIKV isolated in Senegal, 1983, with a nucleotide (nt) identity of at least 81%, belonging to genotype West Africa viral genes. Five GETV sequences were identified, which had a high homology with the GETV sequences isolated from Equus caballus in Japan, 1978, with a (nt) identity of at least 97%. The newly isolated virus CHIKV-China/YN2018-1 became more infectious after passage of the BHK-21 cell line to the Vero cell line. The newly identified RRV gene had the highest homology with the 2006 RRV isolate from Australia, with a (nt) identity of at least 94%. In addition, numerous known and unknown viruses have also been detected in mosquitoes from Yunnan province, China, and propagation tests will be carried out.