Identification and Phylogenetic Characterization of Human Enteroviruses Isolated from Cases of Aseptic Meningitis in Brazil, 2013-2017

Abstract

Aseptic meningitis is a common viral infection associated with human enteroviruses. The aim of the present study was to identify and characterize the enteroviruses associated with outbreaks and sporadic cases of aseptic meningitis that occurred in different regions of Brazil between 2013 and 2017. Cerebrospinal fluids obtained from patients admitted to public health facilities were analyzed. A total of 303 patients were positive for Human Enteroviruses (EV) by cell culture isolation with a median isolation rate throughout the year of 12%. We were able to identify enterovirus serotypes in 295 clinical specimens. Nineteen different serotypes were identified; the large majority corresponded to HEV-B species. Echovirus 30 (E-30) and Echovirus 6 (E-6) were the most prevalent genotypes (66.8%). Sequence analysis suggested that circulating E-30 was closely related to E-30 from other American countries; while E-6 was derived from Europe. Most of the patients consisted of children ≤ 15 years old. The temporal distribution of all aseptic meningitis and EV-positive cases showed an obvious seasonal pattern during autumn. Our results have provided valuable information about the enteroviral etiology of the aseptic meningitis cases in Brazil pointing to the importance of enterovirus surveillance in neurological diseases.

Keywords: aseptic meningitis; echovirus-30; echovirus-6; enterovirus.

Figure 1

Seasonal distribution of aseptic meningitis cases in Brazil from 2013 to 2017 for all patients (a) and EV-positive patients (b).

Figure 2

Proportion of enterovirus detection based on cell culture isolation in aseptic meningitis patients.

Figure 3

Enterovirus serotypes detected between 2013 and 2017 from aseptic meningitis patients. (A). Enterovirus serotypes identified per year (2013–2017). (B). Total number of typed enterovirus and relative number per serotype.

Figure 4

Phylogenetic analysis based on E-30 and E-6 VP1 sequences (876 bp and 867 bp in length, respectively) of Brazilian isolates causing meningitis and other sequences available at the GenBank database. (A) Phylogenetic analysis by maximum likelihood method of VP1 complete sequences. The B species is represented by the blue (E-30) and red (E-6) color. A species (outgroup) and prototypes are represented by black color. (B,C) Maximum clade credibility (MCC) tree based on the Bayesian analysis of the VP1 nucleotide sequences and their closely related sequences. The isolates of the same year are represented by a similar color. Branches are in time scale (year). Posterior probabilities are shown as a color scale.

Figure 4

Phylogenetic analysis based on E-30 and E-6 VP1 sequences (876 bp and 867 bp in length, respectively) of Brazilian isolates causing meningitis and other sequences available at the GenBank database. (A) Phylogenetic analysis by maximum likelihood method of VP1 complete sequences. The B species is represented by the blue (E-30) and red (E-6) color. A species (outgroup) and prototypes are represented by black color. (B,C) Maximum clade credibility (MCC) tree based on the Bayesian analysis of the VP1 nucleotide sequences and their closely related sequences. The isolates of the same year are represented by a similar color. Branches are in time scale (year). Posterior probabilities are shown as a color scale.

Figure 4

Phylogenetic analysis based on E-30 and E-6 VP1 sequences (876 bp and 867 bp in length, respectively) of Brazilian isolates causing meningitis and other sequences available at the GenBank database. (A) Phylogenetic analysis by maximum likelihood method of VP1 complete sequences. The B species is represented by the blue (E-30) and red (E-6) color. A species (outgroup) and prototypes are represented by black color. (B,C) Maximum clade credibility (MCC) tree based on the Bayesian analysis of the VP1 nucleotide sequences and their closely related sequences. The isolates of the same year are represented by a similar color. Branches are in time scale (year). Posterior probabilities are shown as a color scale.