Antiviral effect in association with anti-apoptosis and anti-autophagy of repurposing formoterol fumarate dihydrate on enterovirus A71-infected neuronal cells.

OBJECTIVE: To investigate antiviral activity, anti-apoptosis and anti-autophagy associated with antiviral effect of repurposing formoterol fumarate dihydrate (FFD) against enterovirus A71 (EV-A71) infection in human neuroblastoma cells. METHODS: In vitro antiviral effects of FFD against EV-A71 infection were examined in human neuroblastoma SK-N-SH cells. The impacts on EV-A71 replication were evaluated by progeny virus production, viral RNA synthesis, and viral protein expression. The target of action of FFD against EV-A71 was determined from the effective stage by time-of-addition assay. Moreover, the anti-apoptosis and anti-autophagy activities associated with antiviral effect were observed by detection of apoptosis- and autophagy-related proteins. RESULTS: FFD significantly inhibited EV-A71 replication in neuronal cells through interfering the early stages of replication cycle which might be the steps during uncoating to viral protein synthesis. Additionally, FFD culminated in reducing of EV-A71-induced apoptosis and autophagy with caspase-3-cleaved form and LC3-II expression levels showed markedly decreased while increasing of Bcl-2 and mTOR expression levels. These might indicate the neuroprotective effect of FFD on EV-A71-induced apoptosis and autophagy. CONCLUSIONS: Preliminary mode of action studies showed that repurposing FFD significantly inhibited EV-A71 replication at early stage of viral replication and exhibited anti-apoptosis and anti-autophagy activities in neuronal cells. These findings may provide an opportunity, via drug repurposing of FFD, for a candidate antiviral drug against EV-A71 infection.

Elevation of Cleaved p18 Bax Levels Associated with the Kinetics of Neuronal Cell Death during Japanese Encephalitis Virus Infection.

Japanese encephalitis virus (JEV) infection induces uncontrolled neuronal apoptosis, leading to irreversible brain damage. However, the mechanism of JEV-induced neuronal apoptosis has not been clearly elucidated. This study aimed to investigate both virus replication and neuronal cell apoptosis during JEV infection in human neuroblastoma SH-SY5Y cells. As a result, the kinetic productions of new viral progeny were time- and dose-dependent. The stimulation of SH-SY5Y cell apoptosis was dependent on the multiplicity of infections (MOIs) and infection periods, particularly during the late period of infection. Interestingly, we observed that of full-length Bax (p21 Bax) level started to decrease, which corresponded to the increased level of its cleaved form (p18 Bax). The formation of p18 Bax resulting in cytochrome c release into the cytosol appeared to correlate with JEV-induced apoptotic cell death together with the activation of caspase-3/7 activity, especially during the late stage of a robust viral infection. Therefore, our results suggest another possible mechanism of JEV-induced apoptotic cell death via the induction of the proteolysis of endogenous p21 Bax to generate p18 Bax. This finding could be a new avenue to facilitate novel drug discovery for the further development of therapeutic treatments that could relieve neuronal damage from JEV infection.

Seroprevalence of antibodies to enterovirus 71 and coxsackievirus A16 among people of various age groups in a northeast province of Thailand.

BACKGROUND: Hand, foot and mouth disease (HFMD) is endemic among population of young children in Thailand. The disease is mostly caused by enterovirus 71 (EV71) and coxsackievirus A16 (CA16). METHODS: This study conducted serosurveillance for neutralizing (NT) antibodies to EV71 subgenotypes B5 and C4a, and to CA16 subgenotypes B1a and B1b, in 579 subjects of various ages using a microneutralization assay in human rhabdomyosarcoma (RD) cells. These test viruses were the major circulating subgenotypes associated with HFMD in Thailand during the study period. RESULTS: We found that the levels of seropositivity against all 4 study viruses were lowest in the age group of 6-11 months, i.e., 5.5% had antibody to both EV71 subgenotypes, while 14.5% and 16.4% had antibody to CA16 subgenotypes B1a and B1b, respectively. The percentages of subjects with antibodies to these 4 viruses gradually increased with age, but were still less than 50% in children younger than 3 years. These laboratory data were consistent with the epidemiological data collected by the Ministry of Public Health which showed repeatedly that the highest number of HFMD cases was in children aged 1 year. Analyses of amino acid sequences of the test viruses showed 97% identity between the two subgenotypes of EV71, and 99% between the two subgenotypes of CA16. Nevertheless, the levels of seropositivity and antibody titer against the two subgenotypes of EV71 and of CA16 were not significantly different. CONCLUSIONS: This study clearly demonstrated NT antibody activity across EV71-B5 and EV71-C4a subgenotypes, and also across CA16-B1a and CA16-B1b subgenotypes. Moreover, there were no significant differences by gender in the seropositive rates and antibody levels to any of the 4 virus subgenotypes.