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Articles by Minetaro Arita in JoVE

 JoVE Immunology and Infection

Частица Агглютинация Метод Полиовирус Идентификация


JoVE 2824 4/20/2011

1Department of Virology II, National Institute of Infectious Diseases, 2New Product Design Department, Fujirebio Inc.

Недавно был разработан новый частиц агглютинации (РА) анализ использования молекулы рецептора вируса позволило быстро и легко идентификации полиовируса (PV). В этой статье мы покажем, процедура анализа ПА для идентификации PV.

Other articles by Minetaro Arita on PubMed

Characterization of the Poliovirus 147S Particle: New Insights into Poliovirus Uncoating

A Sabin 1 strain poliovirus (PV) mutant, S1(2Y-1I), carrying a Tyr at amino acid position VP2(142) and an Ile at position VP1(160), can establish persistent infections in HEp-2c cells. This mutant forms atypical 147S particles upon interaction at 0 degrees C with either cells expressing PV receptor (PVR) CD155, or PVR-IgG2a, a chimeric molecule consisting of an extracellular moiety of PVR and the hinge and Fc portion of a mouse IgG2a. Upon interaction with PVR at 37 degrees C, S1(2Y-1I), similar to the parental strain, forms both 135S A particles and 80S empty capsids. At 0 degrees C, surprisingly, at a concentration equal to or greater than 5 nM, PVR-IgG2a induced both the extrusion of VP4 from the capsid of S1(2Y-1I) and the formation of 80S particles. The same transitions were observed at 0 degrees C with the parental strain Sabin 1 at 40 nM PVR-IgG2a. Thus, the formation of 80S particles and VP4 extrusion, considered as one of the steps of PV uncoating, can be temperature-independent at high PVR concentration. This implies that structural changes of the PV capsid occurred following adsorption at low temperature.

Characterization of in Vitro and in Vivo Phenotypes of Poliovirus Type 1 Mutants with Reduced Viral Protein Synthesis Activity

Sabin vaccine strains of poliovirus (PV) contain major attenuation determinants in the internal ribosomal entry site (IRES), an area that directs viral protein synthesis. To examine the effect of reduced viral protein synthesis on PV neurovirulence, spacer sequences, consisting of short open reading frames of different lengths, were introduced between the IRES and the initiation codon of viral polyprotein, resulting in PV mutants with reduced viral protein synthesis. These PV mutants had a viral protein synthesis activity 8.8-55 % of that of the parental Mahoney strain as measured in HeLa S3 cells. Only viruses with more than 28 % of the wild-type activity had intact spacer sequences following plaque purification. Mutants with 17 % or 21 % of the wild-type activity were unstable and a mutant with 8.8 % was lethal. The neurovirulence of PV mutants was evaluated in transgenic mice carrying the human PV receptor gene. In this test, mutants with more than 28 % of the wild-type activity remained neurovirulent, while a mutant with 17 % of wild-type activity exhibited a partially attenuated phenotype. This mutant stably replicated in the spinal cord; however, the stability was severely affected during the course of virus infection from the cerebrum to the spinal cord. These results suggest that reduced viral protein synthesis activity as measured in cultured cells (17-55 % of the wild-type activity) is not the main determinant of PV attenuation.

Circulation of Type 1 Vaccine-derived Poliovirus in the Philippines in 2001

In 2001, highly evolved type 1 circulating vaccine-derived poliovirus (cVDPV) was isolated from three acute flaccid paralysis patients and one contact from three separate communities in the Philippines. Complete genomic sequencing of these four cVDPV isolates revealed that the capsid region was derived from the Sabin 1 vaccine strain but most of the noncapsid region was derived from an unidentified enterovirus unrelated to the oral poliovirus vaccine (OPV) strains. The sequences of the cVDPV isolates were closely related to each other, and the isolates had a common recombination site. Most of the genetic and biological properties of the cVDPV isolates were indistinguishable from those of wild polioviruses. However, the most recently identified cVDPV isolate from a healthy contact retained the temperature sensitivity and partial attenuation phenotypes. The sequence relationships among the isolates and Sabin 1 suggested that cVDPV originated from an OPV dose given in 1998 to 1999 and that cVDPV circulated along a narrow chain of transmission. Type 1 cVDPV was last detected in the Philippines in September 2001, and population immunity to polio was raised by extensive OPV campaigns in late 2001 and early 2002.

Temperature-sensitive Mutants of Enterovirus 71 Show Attenuation in Cynomolgus Monkeys

Enterovirus 71 (EV71) is one of the major causative agents of hand, foot and mouth disease and is sometimes associated with serious neurological disorders. In this study, an attempt was made to identify molecular determinants of EV71 attenuation of neurovirulence in a monkey infection model. An infectious cDNA clone of the virulent strain of EV71 prototype BrCr was constructed; temperature-sensitive (ts) mutations of an attenuated strain of EV71 or of poliovirus (PV) Sabin vaccine strains were then introduced into the infectious clone. In vitro and in vivo phenotypes of the parental and mutant viruses were analysed in cultured cells and in cynomolgus monkeys, respectively. Mutations in 3D polymerase (3D(pol)) and in the 3' non-translated region (NTR), corresponding to ts determinants of Sabin 1, conferred distinct temperature sensitivity to EV71. An EV71 mutant [EV71(S1-3')] carrying mutations in the 5' NTR, 3D(pol) and in the 3' NTR showed attenuated neurovirulence, resulting in limited spread of virus in the central nervous system of monkeys. These results indicate that EV71 and PV1 share common genetic determinants of neurovirulence in monkeys, despite the distinct properties in their original pathogenesis.

A Sabin 3-derived Poliovirus Recombinant Contained a Sequence Homologous with Indigenous Human Enterovirus Species C in the Viral Polymerase Coding Region

Outbreaks of poliomyelitis caused by circulating vaccine-derived polioviruses (cVDPVs) have been reported in areas where indigenous wild polioviruses (PVs) were eliminated by vaccination. Most of these cVDPVs contained unidentified sequences in the nonstructural protein coding region which were considered to be derived from human enterovirus species C (HEV-C) by recombination. In this study, we report isolation of a Sabin 3-derived PV recombinant (Cambodia-02) from an acute flaccid paralysis (AFP) case in Cambodia in 2002. We attempted to identify the putative recombination counterpart of Cambodia-02 by sequence analysis of nonpolio enterovirus isolates from AFP cases in Cambodia from 1999 to 2003. Based on the previously estimated evolution rates of PVs, the recombination event resulting in Cambodia-02 was estimated to have occurred within 6 months after the administration of oral PV vaccine (99.3% nucleotide identity in VP1 region). The 2BC and the 3D(pol) coding regions of Cambodia-02 were grouped into the genetic cluster of indigenous coxsackie A virus type 17 (CAV17) (the highest [87.1%] nucleotide identity) and the cluster of indigenous CAV13-CAV18 (the highest [94.9%] nucleotide identity) by the phylogenic analysis of the HEV-C isolates in 2002, respectively. CAV13-CAV18 and CAV17 were the dominant HEV-C serotypes in 2002 but not in 2001 and in 2003. We found a putative recombination between CAV13-CAV18 and CAV17 in the 3CD(pro) coding region of a CAV17 isolate. These results suggested that a part of the 3D(pol) coding region of PV3(Cambodia-02) was derived from a HEV-C strain genetically related to indigenous CAV13-CAV18 strains in 2002 in Cambodia.

Quantitative Analysis of Poliomyelitis-like Paralysis in Mice Induced by a Poliovirus Replicon

Poliovirus (PV) infection causes severe paralysis, typically of the legs, by destruction of the motor neurons in the spinal cord. In this study, the relationship between PV replication in the spinal cord, damage in the motor neurons and poliomyelitis-like paralysis was analysed in transgenic mice expressing the human PV receptor (TgPVR21). First, a PV replicon encoding firefly luciferase in place of the capsid genes (PV-Fluc mc) was trans-encapsidated in 293T cells and the trans-encapsidated PV-Fluc mc (TE-PV-Fluc mc) was then inoculated into the spinal cords of TgPVR21 mice. TE-PV-Fluc mc was recovered with a titre of 6.3 x 10(7) infectious units ml(-1), which was comparable to those of PV1 strains. TgPVR21 mice inoculated with TE-PV-Fluc mc showed non-lethal paralysis of the hindlimbs, with severity ranging from a decline in grip strength to complete flaccid paralysis. The replication of TE-PV-Fluc mc in the spinal cord reached peak levels at 10 h post-inoculation (p.i.), followed by the appearance of paralysis at as early as 12 h p.i., reaching a plateau at 16 h p.i. Histological analysis showed a correlation between the lesion and the severity of the clinical symptoms in most mice. However, severe paralysis could also be observed with an apparently low lesion score, where as few as 5.3 x 10(2) motor neurons (1.4 % of the susceptible cells in the lumbar cord) were infected by TE-PV-Fluc mc. These results indicate that PV replication in a small population of the motor neurons was critical for severe residual poliomyelitis-like paralysis in TgPVR21 mice.

Rapid Genome Sequencing of RNA Viruses

We developed a system for rapid determination of viral RNA sequences whereby genomic sequence is obtained from cultured virus isolates without subcloning into plasmid vectors. This method affords new opportunities to address the challenges of unknown or untypeable emerging viruses.

An Attenuated Strain of Enterovirus 71 Belonging to Genotype a Showed a Broad Spectrum of Antigenicity with Attenuated Neurovirulence in Cynomolgus Monkeys

Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and is also sometimes associated with serious neurological disorders. In this study, we characterized the antigenicity and tissue specificity of an attenuated strain of EV71 [EV71(S1-3')], which belongs to genotype A, in a monkey infection model. Three cynomolgus monkeys were inoculated with EV71(S1-3'), followed by lethal challenge with the parental virulent strain EV71(BrCr-TR) via an intravenous route on day 45 postinoculation of EV71(S1-3'). Monkeys inoculated with EV71(S1-3') showed a mild neurological symptom (tremor) but survived lethal challenge by virulent EV71(BrCr-TR) without exacerbation of the symptom. The immunized monkey sera showed a broad spectrum of neutralizing activity against different genotypes of EV71, including genotypes A, B1, B4, C2, and C4. For the strains examined, the sera showed the highest neutralization activity against the homotype (genotype A) and the lowest neutralization activity against genotype C2. The order of decreasing neutralization activity of sera was as follows: A > B1 > C4 > B4 > C2. To examine the tissue specificity of EV71(S1-3'), two monkeys were intravenously inoculated with EV71(S1-3'), followed by examination of virus distribution in the central nervous system (CNS) and extraneural tissues. In the CNS, EV71(S1-3') was isolated only from the spinal cord. These results indicate that EV71(S1-3') acts as an effective antigen, although this attenuated strain was still neurotropic when inoculated via the intravenous route.

Cooperative Effect of the Attenuation Determinants Derived from Poliovirus Sabin 1 Strain is Essential for Attenuation of Enterovirus 71 in the NOD/SCID Mouse Infection Model

Enterovirus 71 (EV71) is a causative agent of hand, foot, and mouth disease and is also associated with serious neurological disorders. An attenuated EV71 strain [EV71(S1-3')] has been established in the cynomolgus monkey infection model; this strain contains the attenuation determinants derived from the type 1 poliovirus vaccine strain, Sabin 1 [PV1(Sabin)], in the 5' nontranslated region (NTR), 3D polymerase, and 3' NTR. In this study, we analyzed the effect of the attenuation determinants of PV1(Sabin) on EV71 infection in a NOD/SCID mouse infection model. We isolated a mouse-adapted EV71 strain [EV71(NOD/SCID)] that causes paralysis of the hind limbs in 3- to 4-week-old NOD/SCID mice by adaptation of the virulent EV71(Nagoya) strain in the brains of NOD/SCID mice. A single mutation at nucleotide 2876 that caused an amino acid change in capsid protein VP1 (change of the glycine at position 145 to glutamic acid) was essential for the mouse-adapted phenotype in NOD/SCID mice. Next, we introduced attenuation determinants derived from PV1(Sabin) along with the mouse adaptation mutation into the EV71(Nagoya) genome. In 4-week-old mice, the determinants in the 3D polymerase and 3' NTR, which are the major temperature-sensitive determinants, had a strong effect on attenuation. In contrast, the effect of individual determinants was weak in 3-week-old NOD/SCID mice, and all the determinants were required for substantial attenuation. These results suggest that a cooperative effect of the attenuation determinants of PV1(Sabin) is essential for attenuated neurovirulence of EV71.

Characterization of Pharmacologically Active Compounds That Inhibit Poliovirus and Enterovirus 71 Infectivity

Poliovirus (PV) and enterovirus 71 (EV71) cause severe neurological symptoms in their infections of the central nervous system. To identify compounds with anti-PV and anti-EV71 activities that would not allow the emergence of resistant mutants, we performed drug screening by utilizing a pharmacologically active compound library targeting cellular factors with PV and EV71 pseudoviruses that encapsidated luciferase-encoding replicons. We have found that metrifudil (N-[2-methylphenyl]methyl)-adenosine) (an A2 adenosine receptor agonist), N(6)-benzyladenosine (an A1 adenosine receptor agonist) and NF449 (4,4',4'',4'''-[carbonylbis[imino-5,1,3-benzenetriyl bis(carbonyl-imino)]] tetrakis (benzene-1,3-disulfonic acid) octasodium salt) (a Gs-alpha inhibitor) have anti-EV71 activity, and that GW5074 (3-(3, 5-dibromo-4-hydroxybenzylidine-5-iodo-1,3-dihydro-indol-2-one)) (a Raf-1 inhibitor) has both anti-PV and anti-EV71 activities. EV71 mutants resistant to metrifudil, N(6)-benzyladenosine and NF449 were isolated after passages in the presence of these compounds, but mutants resistant to GW5074 were not isolated for both PV and EV71. The inhibitory effect of GW5074 was not observed in Sendai virus infection and the treatment did not induce the expression of OAS1 and STAT1 mRNA. Small interfering RNA treatment against putative cellular targets of GW5074, including Raf-1, B-Raf, Pim-1, -2, and -3, HIPK2, GAK, MST2 and ATF-3, did not consistently suppress PV replication. Moreover, downregulation of Raf-1 and B-Raf did not affect the sensitivity of RD cells to the inhibitory effect of GW5074. These results suggest that GW5074 has strong and selective inhibitory effect against the replication of PV and EV71 by inhibiting conserved targets in the infection independently of the interferon response.

Cellular Kinase Inhibitors That Suppress Enterovirus Replication Have a Conserved Target in Viral Protein 3A Similar to That of Enviroxime

Previously, we identified a cellular kinase inhibitor, GW5074, that inhibits poliovirus (PV) and enterovirus 71 replication strongly, although its target has remained unknown. To identify the target of GW5074, we searched for cellular kinase inhibitors that have anti-enterovirus activity similar or related to that of GW5074. With this aim, we performed screenings to identify cellular kinase inhibitors that could inhibit PV replication cooperatively with GW5074 or synthetically in the absence of GW5074. We identified MEK1/2 inhibitors (SL327 and U0126), an EGFR inhibitor (AG1478) and a phosphatidylinositol 3-kinase inhibitor (wortmannin) as compounds with a cooperative inhibitory effect with GW5074, and an Akt1/2 inhibitor (Akt inhibitor VIII) as a compound with a synthetic inhibitory effect with MEK1/2 inhibitors and AG1478. Individual treatment with the identified kinase inhibitors did not affect PV replication significantly, but combined treatment with MEK1/2 inhibitor, AG1478 and Akt1/2 inhibitor suppressed the replication synthetically. The effect of AG1478 in this synthetic inhibition was compensated by other receptor tyrosine kinase inhibitors (IGF-1R inhibitor II and Flt3 inhibitor II). We isolated mutants resistant to Flt3 inhibitor II and GW5074 and found that these mutants had cross-resistance to each treatment. These mutants had a common mutation in viral protein 3A that results in an amino acid change at position 70 (Ala to Thr), a mutation that was previously identified in mutants resistant to a potent anti-enterovirus compound, enviroxime. These results suggest that cellular kinase inhibitors and enviroxime have a conserved target in viral protein 3A to suppress enterovirus replication.

Development of a Reverse Transcription-loop-mediated Isothermal Amplification (RT-LAMP) System for a Highly Sensitive Detection of Enterovirus in the Stool Samples of Acute Flaccid Paralysis Cases

In the global eradication program for poliomyelitis, the laboratory diagnosis plays a critical role by isolating poliovirus (PV) from the stool samples of acute flaccid paralysis (AFP) cases. In this study, we developed a reverse transcription-loop-mediated isothermal amplification (RT-LAMP) system for a rapid and highly sensitive detection of enterovirus including PV to identify stool samples positive for enterovirus including PV.

A Bifunctional Anti-enterovirus Compound That Inhibits Replication and the Early Stage of Enterovirus 71 Infection

Enviroxime is an anti-enterovirus compound that targets viral protein 3A and/or 3AB and suppresses a replication step of enterovirus by an unknown mechanism. To date, a number of anti-enterovirus compounds that have little structural similarity to enviroxime but induce common resistance mutations in the 3A-encoding region have been identified. The present study identified a novel type of functionally enviroxime-like compound, AN-12-H5. This compound had no structural similarity to enviroxime or to known enviroxime-like compounds, including TTP-8307, GW5074 and Flt3 Inhibitor II. A resistance phenotype of poliovirus (PV) to these compounds was conferred by a major enviroxime-resistance mutation of PV (G5318A, 3A-Ala70Thr), but not by resistance mutations to guanidine hydrochloride and brefeldin A. AN-12-H5 had a common structure with the anti-enterovirus 71 (EV71) compound AN-23-F6. AN-12-H5 and AN-23-F6 inhibited an early stage of EV71 infection after virus binding to the cells. Mutations in capsid proteins (G3112A, VP1-Ala224Thr, and G2396A, VP3-Arg227Lys mutations) were determined as resistant mutations to AN-12-H5 and AN-23-F6 in the early stage of EV71 infection. These results suggest that AN-12-H5 is a bifunctional anti-enterovirus compound that belongs to a novel class of enviroxime-like compounds and targets both a replication step and an early stage of EV71 infection.

Development of a Particle Agglutination Method with Soluble Virus Receptor for Identification of Poliovirus

In the Global Polio Eradication Initiative, laboratory diagnosis plays a critical role by isolating and identifying poliovirus (PV) from the stool samples of patients with acute flaccid paralysis (AFP). In this study, we developed a particle agglutination (PA) method with a soluble human PV receptor (hPVR) in the form of an immunoadhesin (PVR-IgG2a) for the simple and rapid identification of PV. Sensitized gelatin particles with PVR-IgG2a showed specific agglutination with the culture fluid of PV-infected cells within 2 h of reaction in a one-step procedure. Detection limits for type 1, 2, and 3 PV(Sabin) strains were 1.5 x 10(6) 50% cell culture infectious doses (CCID(50)), 5.3 x 10(5) CCID(50), and 9.1 x 10(5) CCID(50), respectively. Wild-type PVs and PV isolates from acute flaccid paralysis cases examined were identified correctly with this PA method, except for some samples with a mixture of different serotypes of PVs, where a minor population of PV failed to be detected. These results suggest that this PA method is useful for the simple and rapid identification of PV, although the sensitivity was not high enough to detect a minor population of PV (<1/10 of the major population) among mixed PVs.

Biochemical Characterization of Enterovirus 71 3D RNA Polymerase

An unusual enterovirus 71 (EV71) epidemic has begun in China since 2008. EV71 RNA polymerases (3D(pol)) showed polymerase activity with an Mn(2+). Little activity was detected with Co(2+), and no activity was detected with Mg(2+), Ca(2+), Cu(2+), Ni(2+), Cd(2+), or Zn(2+). It is a primer-dependent polymerase, and the enzyme functioned with both di- and 10-nucleotide RNA primers. DNA primer, dT15, increased primer activity, similar to other enterovirus 3D(pol). However, EV71 3D(pol) initiated de novo transcription with a poly(C) template and genome RNA. Its RNA binding activity was weak. Terminal nucleotidyl transferase and reverse transcriptase activity were not detected. The Km and Vmax for EV71 3D(pol) were calculated from classic Lineweaver-Burk plots. The Km values were 2.35±0.05 (ATP), 5.40±0.93 (CTP), 1.12±0.10 (GTP) and 2.81±0.31 (UTP), and the Vmax values were 0.00078±0.00005/min (ATP), 0.011±0.0017/min (CTP), 0.050±0.0043/min (GTP) and 0.0027±0.0005/min (UTP). The Km of EV71 3D(pol) was similar to that of foot and mouth disease virus and rhinovirus. Polymerase activity of BrCr-TR strain and a strain from a clinical isolate in Beijing, 2008 were similar, indicating the potential for 3D(pol) as an antiviral drug target.

Development of a Poliovirus Neutralization Test with Poliovirus Pseudovirus for Measurement of Neutralizing Antibody Titer in Human Serum

In the Global Polio Eradication Initiative, laboratory diagnosis plays a critical role by isolating and identifying poliovirus (PV) from the stool samples from acute flaccid paralysis (AFP) cases. In recent years, reestablishment of PV circulation in countries where PV was previously eliminated has occurred because of decreased herd immunity, possibly due to poor vaccination coverage. To monitor the vulnerability of countries to PV circulation, surveillance of neutralizing-antibody titers against PV in susceptible populations is essential in the end game of the polio eradication program. In this study, we have developed a PV neutralization test with type 1, 2, and 3 PV pseudoviruses to determine the neutralizing-antibody titer against PV in human serum samples. With this test, the neutralizing-antibody titer against PV could be determined within 2 days by automated interpretation of luciferase signals without using infectious PV strains. We validated the pseudovirus PV neutralization test with 131 human serum samples collected from a wide range of age groups (ages 1 to >60 years) by comparison with a conventional neutralization test. We found good correlation in the neutralizing-antibody titers determined by these tests. These results suggest that a pseudovirus PV neutralization test would serve as a safe and simple procedure for the measurement of the neutralizing-antibody titer against PV.

Phosphatidylinositol 4-kinase III Beta is a Target of Enviroxime-like Compounds for Antipoliovirus Activity

Enviroxime is an antienterovirus compound that targets viral protein 3A and/or 3AB and suppresses a step in enterovirus replication by unknown mechanism. To date, four antienterovirus compounds, i.e., GW5074, Flt3 inhibitor II, TTP-8307, and AN-12-H5, are known to have similar mutations in the 3A protein-encoding region causing resistance to enviroxime (a G5318A [3A-Ala70Thr] mutation in poliovirus [PV]) and are considered enviroxime-like compounds. Recently, antienterovirus activity of a phosphatidylinositol 4-kinase III beta (PI4KB) inhibitor, PIK93, was reported, suggesting that PI4KB is an important host factor targetable by antienterovirus compounds (N. Y. Hsu et al., Cell 141:799-811, 2010). In this study, we analyzed the inhibitory effects of previously identified enviroxime-like compounds (GW5074 and AN-12-H5) and a newly identified antienterovirus compound, T-00127-HEV1, on phosphoinositide (PI) kinases. We found that T-00127-HEV1 inhibited PI4KB activity with a higher specificity for than other PI kinases, in contrast to GW5074, which had a broad specificity for PI kinases. In contrast, AN-12-H5 showed no inhibitory effect on PI4KB activity and only moderate inhibitory effects on PI 3-kinase activity. Small interfering RNA (siRNA) screening targeting PI kinases identified PI4KB is a target of GW5074 and T-00127-HEV1, but not of AN-12-H5, for anti-PV activity. Interestingly, T-00127-HEV1 and GW5074 did not inhibit hepatitis C virus (HCV) replication, in contrast to a strong inhibitory effect of AN-12-H5. These results suggested that PI4KB is an enterovirus-specific host factor required for the replication process and targeted by some enviroxime-like compounds (T-00127-HEV1 and GW5074) and that enviroxime-like compounds may have targets other than PI kinases for their antiviral effect.

ACBD3-mediated Recruitment of PI4KB to Picornavirus RNA Replication Sites

Phosphatidylinositol 4-kinase IIIβ (PI4KB) is a host factor required for genome RNA replication of enteroviruses, small non-enveloped viruses belonging to the family Picornaviridae. Here, we demonstrated that PI4KB is also essential for genome replication of another picornavirus, Aichi virus (AiV), but is recruited to the genome replication sites by a different strategy from that utilized by enteroviruses. AiV non-structural proteins, 2B, 2BC, 2C, 3A, and 3AB, interacted with a Golgi protein, acyl-coenzyme A binding domain containing 3 (ACBD3). Furthermore, we identified previously unknown interaction between ACBD3 and PI4KB, which provides a novel manner of Golgi recruitment of PI4KB. Knockdown of ACBD3 or PI4KB suppressed AiV RNA replication. The viral proteins, ACBD3, PI4KB, and phophatidylinositol-4-phosphate (PI4P) localized to the viral RNA replication sites. AiV replication and recruitment of PI4KB to the RNA replication sites were not affected by brefeldin A, in contrast to those in enterovirus infection. These results indicate that a viral protein/ACBD3/PI4KB complex is formed to synthesize PI4P at the AiV RNA replication sites and plays an essential role in viral RNA replication.

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