Co-infection and enterovirus B: post EV-A71 mass vaccination scenario in China

Abstract

Background Hand, foot, and mouth disease (HFMD) is a common child infectious disease caused by more than 20 enterovirus (EV) serotypes. In recent years, enterovirus A71 (EV-A71) has been replaced by Coxsackievirus A6 (CV-A6) to become the predominant serotype. Multiple EV serotypes co-circulate in HFMD epidemics, and this study aimed to investigate the etiological epidemic characteristics of an HFMD outbreak in Kunming, China in 2019. Methods The clinical samples of 459 EV-associated HFMD patients in 2019 were used to amplify the VP1 gene region by the three sets of primers and identify serotypes using the molecular biology method. Phylogenetic analyses were performed based on the VP1 gene. Results Three hundred and forty-eight cases out of 459 HFMD patients were confirmed as EV infection. Of these 191 (41.61%) were single EV infections and 34.20% had co-infections. The EVs were assigned to 18 EV serotypes, of which CV-A6 was predominant (11.33%), followed by CV-B1 (8.93%), CV-A4 (5.23%), CV-A9 (4.58%), CV-A 16 (3.49%) and CV-A10 and CVA5 both 1.96%. Co-infection of CV-A6 with other EVs was present in 15.25% of these cases, followed by co-infection with CV-A16 and other EVs. The VP1 sequences used in the phylogenetic analyses showed that the CV-A6, CV-B1 and CV-A4 sequences belonged to the sub-genogroup D3 and genogroups F and E, respectively. Conclusion Co-circulation and co-infection of multiple serotypes were the etiological characteristic of the HFMD epidemic in Kunming China in 2019 with CV-A-6, CV-B1 and CV-A4 as the predominant serotypes. This is the first report of CV-B1 as a predominant serotype in China and may provide valuable information for the diagnosis, prevention and control of HFMD.

Coxsackievirus B: The important agent of hand, foot, and mouth disease

“…Viral RNA was extracted from stool suspensions by the Axygen Body Fluid DNA/RNA Miniprep Kit (Axygen) and directly tested by nested reverse transcription-polymerase chain reaction (nRT-PCR) using the primers B-OS/B-OAS, B-IS/B-IAS, and 222/224, AN88/AN89, respectively as previously described 8,10 (Supporting Information: Table S1). Most enterovirus species were resolved using a set of primers (224/222 and AN88/AN89) which is suitable for the screening of large samples.…”

“…Given that they are not the predominant serotypes, there is rarely concern about EV‐Bs. However, some studies have found that EV‐Bs such as CV‐B1, CV‐B3, CV‐B4, and CV‐B5 may become important pathogens involved in HFMD 10–13 . At present, five distinct CV‐B4 genotypes (A–E) and four divergent CV‐B5 genogroups (A–D) have been identified, respectively 11,12 .…”

“…6,8,9 However, other EV-B and EV-A serotypes have always co-circulated and also account for a significant proportion in the pathogen spectrum of HFMD. 10 Given that they are not the predominant serotypes, there is rarely concern about EV-Bs.…”

“…However, some studies have found that EV-Bs such as CV-B1, CV-B3, CV-B4, and CV-B5 may become important pathogens involved in HFMD. [10][11][12][13] At present, five distinct CV-B4 genotypes (A-E) and four divergent CV-B5 genogroups (A-D) have been identified, respectively. 11,12 Therefore, the aim of this study was to investigate retrospectively the etiological characteristics of EV-B associated with HFMD in Kunming, Yunnan in 2013, 2015, and 2016 and explore the genetic evolution of CV-B4 and CV-B5 by a retrospective epidemiological study.…”

Construction of a Vero Cell Line Expressing Human ICAM1 for the Development of Rhinovirus Vaccines

“…More recently, a monovalent vaccine against Enterovirus-A71 (EV-A71), responsible for outbreaks of Hand, Foot and Mouth Disease, was approved by the China Food and Drug Administration [ 19 , 20 ]. Since introduction of the vaccine the amount of HFMD cases caused by EV-A71 has dropped markedly [ 21 ], leading to vaccine research into other HFMD-causing enteroviruses [ 22 , 23 , 24 , 25 ] to develop a multivalent HFMD vaccine. EV-D68, previously misclassified as HRV-87 [ 26 ], caused a major outbreak of respiratory disease associated with acute flaccid myelitis in 2014 [ 27 ].…”