Case report: Clinical and virological characteristics of aseptic meningitis caused by a recombinant echovirus 18 in an immunocompetent adult

Metatranscriptomics revealed the molecular characterization of circulating enterovirus strains causing aseptic meningitis in children in Wuxi, China

Enteroviruses are major etiological agents of aseptic meningitis globally, however information on circulating enterovirus types associated with this disease in Wuxi, China is limited. In this study, cerebrospinal fluid samples were collected from 20 pediatric aseptic meningitis cases in a Wuxi hospital in 2020 and subjected to metagenomic analysis to detect pathogens. Enterovirus B was detected in 9 cases, including 7 echovirus 18 (E18) and 2 echovirus 11 (E11) strains. The E18 strains exhibited 87.5-98.2% nucleotide identity and phylogenetically clustered with other China E18 strains, while the E11 strains showed 97.59% identity and clustered within the D5 subgroup along with other China E11 strains. One E18 strain was identified as a novel recombinants with a distinct recombination breakpoint within 3D gene. These findings expand knowledge on enteroviruses associated with pediatric aseptic meningitis in Wuxi, and highlight the circulation of genetically diverse E18 and E11 strains, including novel E18 recombinants. Characterization of enterovirus diversity by metagenomic analysis is important for molecular diagnosis and epidemiological tracking of aseptic meningitis cases. Continued surveillance of circulating enterovirus strains in Wuxi that may cause future outbreaks is warranted.

Neurotropic enteroviruses (Picornaviridae: Enterovirus): predominant types, basis of neurovirulence

Enteroviruses are one of the most common causative agents of infectious diseases of the central nervous system. They are characterized by genetic variability, the ability to infect a wide range of cells, including brain microglial cells and astrocytes, and persist in the central nervous system tissue, causing delayed and chronic diseases. The review presents data on the basis of neurovirulence of non-polio enteroviruses and the most common pathogens causing enteroviral neuroinfections.

Genetic Characteristics and Phylogeographic Dynamics of Echovirus

Echoviruses belong to the genus Enterovirus in the Picornaviridae family, forming a large group of Enterovirus B (EV-B) within the Enteroviruses. Previously, Echoviruses were classified based on the coding sequence of VP1. In this study, we performed a reliable phylogenetic classification of 277 sequences isolated from 1992 to 2019 based on the full-length genomes of Echovirus. In this report, phylogenetic, phylogeographic, recombination, and amino acid variability landscape analyses were performed to reveal the evolutional characteristics of Echovirus worldwide. Echoviruses were clustered into nine major clades, e.g., G1-G9. Phylogeographic analysis showed that branches G2-G9 were linked to common strains, while the branch G1 was only linked to G5. In contrast, strains E12, E14, and E16 clustered separately from their G3 and G7 clades respectively, and became a separate branch. In addition, we identified a total of 93 recombination events, where most of the events occurred within the VP1-VP4 coding regions. Analysis of amino acid variation showed high variability in the a positions of VP2, VP1, and VP3. This study updates the phylogenetic and phylogeographic information of Echovirus and indicates that extensive recombination and significant amino acid variation in the capsid proteins drove the emergence of new strains.