scholarly journals BPIFB3 facilitates flavivirus infection by controlling RETREG1-dependent reticulophagy

2018 ◽  
Author(s):  
Azia S. Evans ◽  
Nicholas J. Lennemann ◽  
Ka man Fan ◽  
Carolyn B. Coyne

AbstractThe flavivirus genus, which includes dengue virus (DENV) and Zika virus (ZIKV), are significant human pathogens and the prevalence of infected vectors continues to geographically expand. Both DENV and ZIKV rely on expansion of the endoplasmic reticulum (ER) and the induction of autophagy to establish a productive viral infection. However, little is known regarding the interplay between the requirements for autophagy initiation during infection and the mechanisms used by these viruses to avoid clearance through the autophagic pathway. We recently showed that DENV and ZIKV inhibit reticulophagy (specific degradation of the ER through autophagy) by cleaving reticulophagy regulator 1 (RETREG1), an autophagy receptor responsible for targeted ER sheet degradation. These data suggest that DENV and ZIKV require specific autophagic pathways for their replication, while other autophagic pathways are antiviral. We previously identified BPI Fold Containing Family B Member 3 (BPIFB3) as a regulator of autophagy that negatively controls enterovirus replication. Here, we show that in contrast to enteroviruses, BPIFB3 functions as a positive regulator of DENV and ZIKV infection and that its RNAi-mediated silencing drastically inhibits the formation of viral replication organelles. We show that BPIFB3 depletion enhances ER fragmentation, while its overexpression protects against autophagy-induced ER degradation, demonstrating that BPIFB3 serves as a specific regulator of ER turnover. We further show that the antiviral effects of BPIFB3 depletion on flavivirus infection are reversed in RETREG1-depleted cells, and that BPIFB3 associates with RETREG1 within the ER, suggesting that BPIFB3 regulates a RETREG1-specific reticulophagy pathway. Collectively, these studies identify BPIFB3 as a regulator of the reticulophagy pathway and define the requirements for a novel host regulator of flavivirus infection.Author SummaryFlaviviruses and other arthropod transmitted viruses represent a widespread global health problem with limited treatment options currently available. Thus, greater knowledge of the host factors required for replication and transmission is needed to provide a better understanding of the cellular requirements for infection. Here, we show that the endoplasmic reticulum (ER) localized protein, BPIFB3 is required to facilitate flavivirus infection. Depletion of BPIFB3 in cells inhibits dengue virus and Zika virus infection prior to replication of the viral genome. Mechanistically, we show that BPIFB3 inhibits ER degradation in an autophagy-specific manner and that loss of BPIFB3 decreases the availability of ER membranes needed for flavivirus replication. We further show that BPIFB3 specifically regulates the RETREG1 pathway, but not other pathways of ER turnover. Together, our data define a previously uncharacterized method of regulating ER degradation and show that BPIFB3 is an essential host factor for a productive flavivirus infection.

2020 ◽  
Vol 94 (9) ◽  
Author(s):  
Azia S. Evans ◽  
Nicholas J. Lennemann ◽  
Carolyn B. Coyne

ABSTRACT Flaviviruses, including dengue virus (DENV) and Zika virus (ZIKV), rely heavily on the availability of endoplasmic reticulum (ER) membranes throughout their life cycle, and degradation of ER membranes restricts flavivirus replication. Accordingly, DENV and ZIKV restrict ER turnover by protease-mediated cleavage of reticulophagy regulator 1 (RETREG1), also known as FAM134B, an autophagy receptor responsible for targeted ER sheet degradation. Given that the induction of autophagy may play an important role in flavivirus replication, the antiviral role of RETREG1 suggests that specialized autophagic pathways may have differential effects on the flavivirus life cycle. We previously identified BPI fold-containing family B member 3 (BPIFB3) as a regulator of autophagy that negatively controls enterovirus replication. Here, we show that in contrast to enteroviruses, BPIFB3 functions as a positive regulator of DENV and ZIKV infection and that its RNA interference-mediated silencing inhibits the formation of viral replication organelles. Mechanistically, we show that depletion of BPIFB3 enhances RETREG1-dependent reticulophagy, leading to enhanced ER turnover and the suppression of viral replication. Consistent with this, the antiviral effects of BPIFB3 depletion can be reversed by RETREG1 silencing, suggesting a specific role for BPIFB3 in regulating ER turnover. These studies define BPIFB3 as a required host factor for both DENV and ZIKV replication and further contribute to our understanding of the requirements for autophagy during flavivirus infection. IMPORTANCE Flaviviruses and other arthropod-transmitted viruses represent a widespread global health problem, with limited treatment options currently available. Thus, a better understanding of the cellular requirements for their infection is needed. Both DENV and ZIKV rely on expansion of the endoplasmic reticulum (ER) and the induction of autophagy to establish productive infections. However, little is known regarding the interplay between the requirements for autophagy initiation during infection and the mechanisms used by these viruses to avoid clearance through the autophagic pathway. Our study highlights the importance of the host factor BPIFB3 in regulating flavivirus replication and further confirms that the RETREG1-dependent reticulophagy pathway is antiviral to both DENV and ZIKV.


Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3779
Author(s):  
Ruben Soto-Acosta ◽  
Eunkyung Jung ◽  
Li Qiu ◽  
Daniel J. Wilson ◽  
Robert J. Geraghty ◽  
...  

Discovery of compound 1 as a Zika virus (ZIKV) inhibitor has prompted us to investigate its 7H-pyrrolo[2,3-d]pyrimidine scaffold, revealing structural features that elicit antiviral activity. Furthermore, we have demonstrated that 9H-purine or 1H-pyrazolo[3,4-d]pyrimidine can serve as an alternative core structure. Overall, we have identified 4,7-disubstituted 7H-pyrrolo[2,3-d]pyrimidines and their analogs including compounds 1, 8 and 11 as promising antiviral agents against flaviviruses ZIKV and dengue virus (DENV). While the molecular target of these compounds is yet to be elucidated, 4,7-disubstituted 7H-pyrrolo[2,3-d]pyrimidines and their analogs are new chemotypes in the design of small molecules against flaviviruses, an important group of human pathogens.


2020 ◽  
Author(s):  
Rory K. M. Long ◽  
Kathleen P. Moriarty ◽  
Ben Cardoen ◽  
Guang Gao ◽  
A. Wayne Vogl ◽  
...  

AbstractThe endoplasmic reticulum (ER) is a complex subcellular organelle composed of diverse structures such as tubules, sheets and tubular matrices. Flaviviruses such as Zika virus (ZIKV) induce reorganization of endoplasmic reticulum (ER) membranes to facilitate viral replication. Here, using 3D super resolution microscopy, ZIKV infection is shown to induce the formation of dense tubular matrices associated with viral replication in the central ER. Viral non-structural proteins NS4B and NS2B associate with replication complexes within the ZIKV-induced tubular matrix and exhibit distinct ER distributions outside this central ER region. Deep neural networks trained to identify ZIKV-infected versus mock-infected cells successfully identified ZIKV-induced central ER tubular matrices as a determinant of viral infection. Super resolution microscopy and deep learning are therefore able to identify and localize morphological features of the ER and may be of use to screen for inhibitors of infection by ER-reorganizing viruses.


2016 ◽  
Vol 54 (4) ◽  
pp. 860-867 ◽  
Author(s):  
Jesse J. Waggoner ◽  
Benjamin A. Pinsky

Zika virus (ZIKV) is anAedesmosquito-borne flavivirus that emerged in Brazil in 2015 and then rapidly spread throughout the tropical and subtropical Americas. Based on clinical criteria alone, ZIKV cannot be reliably distinguished from infections with other pathogens that cause an undifferentiated systemic febrile illness, including infections with two common arboviruses, dengue virus and chikungunya virus. This minireview details the methods that are available to diagnose ZIKV infection.


Vaccines ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 72 ◽  
Author(s):  
Gustavo Cabral-Miranda ◽  
Stephanie M. Lim ◽  
Mona O. Mohsen ◽  
Ilya V. Pobelov ◽  
Elisa S. Roesti ◽  
...  

Zika virus (ZIKV) is a flavivirus similar to Dengue virus (DENV) in terms of transmission and clinical manifestations, and usually both viruses are found to co-circulate. ZIKV is usually transmitted by mosquitoes bites, but may also be transmitted by blood transfusion, via the maternal–foetal route, and sexually. After 2015, when the most extensive outbreak of ZIKV had occurred in Brazil and subsequently spread throughout the rest of South America, it became evident that ZIKV infection during the first trimester of pregnancy was associated with microcephaly and other neurological complications in newborns. As a result, the development of a vaccine against ZIKV became an urgent goal. A major issue with DENV vaccines, and therefore likely also with ZIKV vaccines, is the induction of antibodies that fail to neutralize the virus properly and cause antibody-dependent enhancement (ADE) of the infection instead. It has previously been shown that antibodies against the third domain of the envelope protein (EDIII) induces optimally neutralizing antibodies with no evidence for ADE for other viral strains. Therefore, we generated a ZIKV vaccine based on the EDIII domain displayed on the immunologically optimized Cucumber mosaic virus (CuMVtt) derived virus-like particles (VLPs) formulated in dioleoyl phosphatidylserine (DOPS) as adjuvant. The vaccine induced high levels of specific IgG after a single injection. The antibodies were able to neutralise ZIKV without enhancing infection by DENV in vitro. Thus, the here described vaccine based on EDIII displayed on VLPs was able to stimulate production of antibodies specifically neutralizing ZIKV without potentially enhancing disease caused by DENV.


2018 ◽  
Vol 92 (7) ◽  
Author(s):  
Bobby Brooke Herrera ◽  
Wen-Yang Tsai ◽  
Charlotte A. Chang ◽  
Donald J. Hamel ◽  
Wei-Kung Wang ◽  
...  

ABSTRACT Recent studies on the role of T cells in Zika virus (ZIKV) infection have shown that T cell responses to Asian ZIKV infection are important for protection, and that previous dengue virus (DENV) exposure amplifies the protective T cell response to Asian ZIKV. Human T cell responses to African ZIKV infection, however, remain unexplored. Here, we utilized the modified anthrax toxin delivery system to develop a flavivirus enzyme-linked immunosorbent spot (ELISPOT) assay. Using human ZIKV and DENV samples from Senegal, West Africa, our results demonstrate specific and cross-reactive T cell responses to nonstructural protein 3 (NS3). Specifically, we found that T cell responses to NS3 protease are ZIKV and DENV specific, but responses to NS3 helicase are cross-reactive. Sequential sample analyses revealed immune responses sustained many years after infection. These results have important implications for African ZIKV/DENV vaccine development, as well as for potential flavivirus diagnostics based on T cell responses. IMPORTANCE The recent Zika virus (ZIKV) epidemic in Latin America and the associated congenital microcephaly and Guillain-Barré syndrome have raised questions as to why we have not recognized these distinct clinical diseases in Africa. The human immunologic response to ZIKV and related flaviviruses in Africa represents a research gap that may shed light on the mechanisms contributing to protection. The goal of our study was to develop an inexpensive assay to detect and characterize the T cell response to African ZIKV and DENV. Our data show long-term specific and cross-reactive human immune responses against African ZIKV and DENV, suggesting the usefulness of a diagnostic based on the T cell response. Additionally, we show that prior flavivirus exposure influences the magnitude of the T cell response. The identification of immune responses to African ZIKV and DENV is of relevance to vaccine development.


2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Yu-Wen Chien ◽  
Tzu-Chuan Ho ◽  
Pei-Wen Huang ◽  
Nai-Ying Ko ◽  
Wen-Chien Ko ◽  
...  

Abstract Background We recently conducted a serosurvey of newly arrived workers in Taiwan from four Southeast Asian countries which revealed that 1% of the migrant workers had laboratory-confirmed recent Zika virus (ZIKV) infection. Taiwan, where Aedes mosquitoes are prevalent, has a close relationship with Southeast Asian countries. Up to now, 21 imported cases of ZIKV infection have been reported in Taiwan, but there has been no confirmed indigenous case. The aim of this serosurvey was to assess whether there was unrecognized ZIKV infections in Taiwan. Methods A total of 212 serum samples collected in a cross-sectional seroepidemiologic study conducted during the end of the 2015 dengue epidemic in Tainan, Taiwan, were analyzed. Anti-ZIKV IgM and IgG were tested using commercial enzyme-linked immunosorbent assays (ELISAs). Plaque reduction neutralization tests (PRNTs) for ZIKV and four dengue virus (DENV) serotypes were performed for samples with positive anti-ZIKV antibodies. A confirmed case of ZIKV infection was defined by ZIKV PRNT90 titer ratio ≥ 4 compared to four DENV serotypes. Results The mean age of the 212 participants was 54.0 years (standard deviation 13.7 years), and female was predominant (67.0%). Anti-ZIKV IgM and IgG were detected in 0 (0%) and 9 (4.2%) of the 212 participants, respectively. For the 9 samples with anti-ZIKV IgG, only 1 sample had 4 times higher ZIKV PRNT90 titers compared to PRNT90 titers against four dengue virus serotypes; this individual denied having traveled abroad. Conclusions The results suggest that undetected indigenous ZIKV transmission might have occurred in Taiwan. The findings also suggest that the threat of epidemic transmission of ZIKV in Taiwan does exist due to extremely low-level of herd immunity. Our study also indicates that serological tests for ZIKV-specific IgG remain a big challenge due to cross-reactivity, even in dengue non-endemic countries.


Vaccines ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 307 ◽  
Author(s):  
César López-Camacho ◽  
Giuditta De Lorenzo ◽  
Jose Luis Slon-Campos ◽  
Stuart Dowall ◽  
Peter Abbink ◽  
...  

The flavivirus envelope protein domain III (EDIII) was an effective immunogen against dengue virus (DENV) and other related flaviviruses. Whether this can be applied to the Zika virus (ZIKV) vaccinology remains an open question. Here, we tested the efficacy of ZIKV-EDIII against ZIKV infection, using several vaccine platforms that present the antigen in various ways. We provide data demonstrating that mice vaccinated with a ZIKV-EDIII as DNA or protein-based vaccines failed to raise fully neutralizing antibodies and did not control viremia, following a ZIKV challenge, despite eliciting robust antibody responses. Furthermore, we showed that ZIKV-EDIII encoded in replication-deficient Chimpanzee adenovirus (ChAdOx1-EDIII) elicited anti-ZIKV envelope antibodies in vaccinated mice but also provided limited protection against ZIKV in two physiologically different mouse challenge models. Taken together, our data indicate that contrary to what was shown for other flaviviruses like the dengue virus, which has close similarities with ZIKV-EDIII, this antigen might not be a suitable vaccine candidate for the correct induction of protective immune responses against ZIKV.


2019 ◽  
Vol 20 (5) ◽  
pp. 1101 ◽  
Author(s):  
Jae Lee ◽  
Ok Shin

Emerging mosquito-transmitted RNA viruses, such as Zika virus (ZIKV) and Chikungunya represent human pathogens of an immense global health problem. In particular, ZIKV has emerged explosively since 2007 to cause a series of epidemics in the South Pacific and most recently in the Americas. Although typical ZIKV infections are asymptomatic, ZIKV infection during pregnancy is increasingly associated with microcephaly and other fetal developmental abnormalities. In the last few years, genomic and molecular investigations have established a remarkable progress on the pathogenic mechanisms of ZIKV infection using in vitro and in vivo models. Here, we highlight recent advances in ZIKV-host cell interaction studies, including cellular targets of ZIKV, ZIKV-mediated cell death mechanisms, host cell restriction factors that limit ZIKV replication, and immune evasion mechanisms utilized by ZIKV. Understanding of the mechanisms of ZIKV–host interaction at the cellular level will contribute crucial insights into the development of ZIKV therapeutics and vaccines.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Rory K. M. Long ◽  
Kathleen P. Moriarty ◽  
Ben Cardoen ◽  
Guang Gao ◽  
A. Wayne Vogl ◽  
...  

AbstractThe endoplasmic reticulum (ER) is a complex subcellular organelle composed of diverse structures such as tubules, sheets and tubular matrices. Flaviviruses such as Zika virus (ZIKV) induce reorganization of ER membranes to facilitate viral replication. Here, using 3D super resolution microscopy, ZIKV infection is shown to induce the formation of dense tubular matrices associated with viral replication in the central ER. Viral non-structural proteins NS4B and NS2B associate with replication complexes within the ZIKV-induced tubular matrix and exhibit distinct ER distributions outside this central ER region. Deep neural networks trained to distinguish ZIKV-infected versus mock-infected cells successfully identified ZIKV-induced central ER tubular matrices as a determinant of viral infection. Super resolution microscopy and deep learning are therefore able to identify and localize morphological features of the ER and allow for better understanding of how ER morphology changes due to viral infection.


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