iPS cell-derived model to study the interaction between tissue macrophage and HIV-1.

Despite effective antiretroviral therapy, HIV-1 persists in cells, including macrophages, which is an obstacle to cure. However, the precise role of macrophages in HIV-1 infection remains unclear because they reside in tissues that are not easily accessible. Monocyte-derived macrophages are widely used as a model in which peripheral blood monocytes are cultured and differentiated into macrophages. However, another model is needed because recent studies revealed that most macrophages in adult tissues originate from the yolk sac and fetal liver precursors rather than monocytes, and the embryonic macrophages possess a self-renewal (proliferating) capacity that monocyte-derived macrophages lack. Here, we show that human induced pluripotent stem cell-derived immortalized macrophage-like cells are a useful self-renewing macrophage model. They proliferate in a cytokine-dependent manner, retain macrophage functions, support HIV-1 replication, and exhibit infected monocyte-derived macrophage-like phenotypes, such as enhanced tunneling nanotube formation and cell motility, as well as resistance to a viral cytopathic effect. However, several differences are also observed between monocyte-derived macrophages and induced pluripotent stem cell-derived immortalized macrophage-like cells, most of which can be explained by the proliferation of induced pluripotent stem cell-derived immortalized macrophage-like cells. For instance, proviruses with large internal deletions, which increased over time in individuals receiving antiretroviral therapy, are enriched more rapidly in induced pluripotent stem cell-derived immortalized macrophage-like cells. Interestingly, inhibition of viral transcription by HIV-1-suppressing agents is more obvious in induced pluripotent stem cell-derived immortalized macrophage-like cells. Collectively, our present study proposes that the model of induced pluripotent stem cell-derived immortalized macrophage-like cells is suitable for mimicking the interplay between HIV-1 and self-renewing tissue macrophages, the newly recognized major population in most tissues that cannot be fully modeled by monocyte-derived macrophages alone.

Development of a rapid assay system for detecting antibody-dependent enhancement of dengue virus infection.

Antibody-dependent enhancement (ADE) is one of the pathogenic mechanisms related to disease severity in dengue virus infection. Conventional assays for detecting ADE activity usually require several days. In this study, we established a rapid assay system to evaluate ADE activity in dengue-seropositive samples using single round infectious particles (SRIPs). Human Fc-gamma receptor-bearing cells (K562 and Mylc cells) were infected with SRIP antigen in the presence of human serum samples to measure ADE activity. Two assay protocols were introduced: (i) rapid assay with 5 h of incubation, and (ii) semi-rapid assay with 24 h of incubation. The rapid assay requires a large quantity of SRIP antigen and gives results in half a day. Although the semi-rapid assay requires slightly more than a day, it can be performed using only a small amount of SRIP. Interestingly, the range of the number of Mylc cells required for the semi-rapid assay was wider than that of K562 cells. Significant correlations were observed between the rapid and semi-rapid assays for both cell types. Although it is difficult to judge which protocol best reflects the current immune status in vivo, both assays could rapidly provide valuable information regarding the risk assessment for severe diseases.

Reevaluation of antibody-dependent enhancement of infection in anti-SARS-CoV-2 therapeutic antibodies and mRNA-vaccine antisera using FcR- and ACE2-positive cells.

Many therapeutic antibodies (Abs) and mRNA vaccines, both targeting SARS-CoV-2 spike protein (S-protein), have been developed and approved in order to combat the ongoing COVID-19 pandemic. In consideration of these developments, a common concern has been the potential for Ab-dependent enhancement (ADE) of infection caused by inoculated or induced Abs. Although the preventive and therapeutic effects of these Abs are obvious, little attention has been paid to the influence of the remaining and dwindling anti-S-protein Abs in vivo. Here, we demonstrate that certain monoclonal Abs (mAbs) approved as therapeutic neutralizing anti-S-protein mAbs for human usage have the potential to cause ADE in a narrow range of Ab concentrations. Although sera collected from mRNA-vaccinated individuals exhibited neutralizing activity, some sera gradually exhibited dominance of ADE activity in a time-dependent manner. None of the sera examined exhibited neutralizing activity against infection with the Omicron strain. Rather, some ADE of Omicron infection was observed in some sera. These results suggest the possible emergence of adverse effects caused by these Abs in addition to the therapeutic or preventive effect.

The potential of COVID-19 patients' sera to cause antibody-dependent enhancement of infection and IL-6 production.

Since the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), many vaccine trials have been initiated. An important goal of vaccination is the development of neutralizing antibody (Ab) against SARS-CoV-2. However, the possible induction of antibody-dependent enhancement (ADE) of infection, which is known for other coronaviruses and dengue virus infections, is a particular concern in vaccine development. Here, we demonstrated that human iPS cell-derived, immortalized, and ACE2- and TMPRSS2-expressing myeloid cell lines are useful as host cells for SARS-CoV-2 infection. The established cell lines were cloned and screened based on their function in terms of susceptibility to SARS-CoV-2-infection or IL-6 productivity. Using the resulting K-ML2 (AT) clone 35 for SARS-CoV-2-infection or its subclone 35-40 for IL-6 productivity, it was possible to evaluate the potential of sera from severe COVID-19 patients to cause ADE and to stimulate IL-6 production upon infection with SARS-CoV-2.

Dengue virus susceptibility in novel immortalized myeloid cells.

Human dendritic cells (DCs) are the main target cells of dengue virus (DENV). Because humans injected with even a small volume of DENV from mosquito saliva display a high level of viremia, DCs are expected to be highly susceptible to DENV. In the present study, we assessed the efficiency of DENV infection using the novel immortalized human myeloid cell lines iPS-ML and iPS-DC. To prepare the DC-like myeloid cell line (iPS-DC), iPS-ML cells were cultured in the presence of IL-4 for 72 h. iPS-DC cells were the most susceptible to DENV, followed by iPS-ML, Vero and K562 cells. In contrast, the highest infective yield titer was observed in Vero cells. To investigate further uses of iPS-ML and iPS-DC, these cells were applied to an assay measuring antibody-dependent enhancement (ADE) activity in DENV infection. Serum samples collected from healthy Thai participants and mouse monoclonal antibodies displayed similar ADE activity patterns when examined with iPS-ML, iPS-DC, or K562 cells, the last of which are usually used in conventional ADE assays. Interestingly, iPS-ML cells showed greater susceptibility to ADE activity than iPS-DC and K562 cells. Here, we demonstrated the potential utility of the novel immortalized human myeloid cell lines iPS-ML and iPS-DC in future research on DENV.

Design, synthesis, and optimization of a series of 2-azaspiro[3.3]heptane derivatives as orally bioavailable fetal hemoglobin inducers.

Pharmacological reactivation of the γ-globin gene for the production of fetal hemoglobin (HbF) is a promising approach for the management of ß-thalassemia and sickle cell disease (SCD). We conducted a phenotypic screen in human erythroid progenitor cells to identify molecules that could induce HbF, which resulted in identification of the hit compound 1. Exploration of structure-activity relationships and optimization of ADME properties led to 2-azaspiro[3.3]heptane derivative 18, which is more rigid and has a unique structure. In vivo using cynomolgus monkeys, compound 18 induced a significant dose-dependent increase in globin switching, with developable properties. Moreover, compound 18 showed no genotoxic effects and was much safer than hydroxyurea. These findings could facilitate the development of effective new therapies for the treatment of ß-hemoglobinopathies, including SCD.

Phenotypic-screening generates active novel fetal globin-inducers that downregulate Bcl11a in a monkey model.

Heritable disorders associated with hemoglobin production are the most common monogenic disorders. These are mainly represented by disorders such as ß-thalassemia and sickle cell disease. Induction of fetal hemoglobin (HbF) has been known to ameliorate the clinical severity of these ß hemoglobinopathies. A high throughput phenotypic screening was used in this study to isolate novel compounds that may enhance the expression of γ-globin, the component of HbF, in human erythroid cell lines and primary erythroid progenitors derived from human CD34+ cells. The effect of lead compounds on epigenetic enzymes and key transcriptional factors was evaluated to identify their mode of action. One hit compound was further evaluated in vivo using monkey models. Among the ~18,000 compounds screened, 18 compounds were selected and tested to determine their ability to induce HbF in human erythroid cell lines and primary erythroid cells. One of these compounds, a 3-phenyl-isoxazole derivative, could potentially induce HbF in monkey bone marrow cells when administered orally. The compound downregulated negative transcriptional regulators of HbF, Bcl11a and LRF without inhibiting the known epigenetic enzymes. These studies demonstrated the advantages associated with phenotype-screening and identified novel fetal globin inducers that may be useful for treating hemoglobinopathies.

Discovery and in vivo effects of novel human natriuretic peptide receptor A (NPR-A) agonists with improved activity for rat NPR-A.

Natriuretic peptide receptor A (NPR-A) agonists were evaluated in vivo by optimizing the structure of quinazoline derivatives to improve agonistic activity for rat NPR-A. A 1,4-Cis-aminocyclohexylurea moiety at 4-position and hydroxy group of d-alaninol at 2-position on the quinazoline ring were found to be important factors in improving rat NPR-A activity. We identified potent quinazoline and pyrido[2,3-d]pyrimidine derivatives against rat NPR-A, with double-digit nanomolar EC50 values. The in vivo results showed that compound 56b administered at 1.0 mg/kg/min significantly increased plasma cGMP concentration and urine volume in rats. We discovered novel potent NPR-A agonists that showed agonistic effects similar to those of atrial natriuretic peptide.

Human metapneumovirus infection in febrile children with lower respiratory diseases in primary care settings in Hiroshima, Japan.

Human metapneumovirus (hMPV) has been shown to be a leading cause of viral lower respiratory tract infections in children. Nevertheless, few reports regarding hMPV infections over consecutive years in children in primary care settings are available. We carried out virologic and clinical studies to determine the role of hMPV in febrile lower respiratory infections in children at a primary care clinic over 3 years and 5 months. Nasopharyngeal aspirates obtained from children with acute respiratory tract infections accompanied by high-grade fever (> or = 39 degrees C) and productive cough were studied for hMPV by reverse transcription-polymerase chain reaction and for other respiratory viruses by viral cultures and immunoassays. Of 379 patients tested, 202 were positive for at least 1 virus, including 98 with hMPV, 69 with respiratory syncytial virus, 18 with adenovirus, 12 with enterovirus, 8 with parainfluenza virus, 3 with rhinovirus, 2 with influenza virus type C, and 1 with herpes simplex virus. The male:female ratio of hMPV-infected children was 0.96:1 with an overall mean age of 3.5 years (range, 2 months to 9 years). These infections occurred predominantly from February to July, and the hospitalization rate was 4%. Of 93 patients infected with hMPV alone, 52 (56%) showed evidence of a lower respiratory tract infection.

Simultaneous detection and genogroup-screening test for norovirus genogroups I and II from fecal specimens in single tube by reverse transcription- loop-mediated isothermal amplification assay.

We developed a reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for the rapid detection of noroviruses (NoVs) in a genogroup-specific manner in a previous study. In this study, to detect NoVs more easily and simply, we have developed an RT-LAMP assay for the simultaneous detection of NoV genogroup I (GI) and II (GII) genomes in a single tube. The genogrouping was achieved by using fluorescence-labeled primers, and the green and red colors for GI and GII, respectively, sometimes with yellow color for GI and GII mixture, were indicated on the agarose gel under UV light at 312 nm.

[Evaluation of immunochromatography test for rapid detection of influenza A and B viruses using real-time PCR].

The sensitivity of rapid diagnostic kits to influenza B is lower than to influenza A. The cause-poor performance of the kit or the scarcity of viruses in type B specimens-has yet to be clarified. Using real-time PCR, we measured the amount of influenza viruses with nasopharyngeal aspirate fluid previously identified by virus isolation culture and passing the rapid diagnosis test by four types of kits, including the ESPLINE Influenza A&B-N (Fujirebio Corp., Japan). We classified the results of virus isolation and rapid diagnosis tests into three groups and examined them: group 1 (12 specimens, influenza B, all negative in tests using four types of kits); group 2 (57 specimens, influenza B, all positive in tests); and group 3 (36 specimens, AH3, all positive in tests). The average amount of viruses in group 1 (6.60 +/- 0.81 log10copies/mL) was significantly lower (p<0.0001) than that in group 2 (8.51 +/- 0.57 log10copies/mL) or group 3 (8.72 +/- 0.63 log10copies/mL). No significant difference was seen in the amount of viruses between groups 2 and 3. We concluded that the cause of low sensitivity in rapid diagnostic kits to influenza B are attributable to the scarcity of viruses in the specimen.

Rapid detection of norovirus from fecal specimens by real-time reverse transcription-loop-mediated isothermal amplification assay.

In this study, we developed a one-step, single-tube genogroup-specific reverse transcription-loop-mediated isothermal amplification (RT-LAMP) assay for the detection of norovirus (NoV) genomes targeting from the C terminus of the RNA-dependent RNA polymerase gene to the capsid N-terminal/shell domain region. This is the first report on the development of an RT-LAMP assay for the detection of NoV genomes. Because of the diversity of NoV genotypes, we used 9 and 13 specially designed primers containing mixed bases for genogroup I (GI) and II (GII), respectively. The RT-LAMP assay had the advantages of rapidity, simplicity, specificity, and selectively and could obtain results within 90 min, generally even within 60 min, under isothermal conditions at 62 degrees C. The detection limits for NoV genomes were between 10(2) and 10(3) copies/tube for GI and GII with differentiation by genotype, and no cross-reactions among NoV GI and GII and other gastroenteritis viruses, such as sapovirus, human astrovirus, adenovirus type 40 and 41, and group A and C rotavirus, were found. In the evaluation tests with fecal specimens obtained from gastroenteritis outbreaks, the sensitivity and specificity of the RT-LAMP assay with regard to RT-PCR were 100 and 94% for GI and 100 and 100% for GII, respectively. These findings establish that the RT-LAMP assay is potentially useful for the rapid detection of NoV genomes from fecal specimens in outbreaks of food-borne and person-to-person-transmitted gastroenteritis.

[Eleven cases of co-infection with influenza type A and type B suspected by use of a rapid diagnostic kit and confirmed by RT-PCR and virus isolation].

In the 2004/05 influenza season there were epidemics of influenza caused by several types of viruses (type B and A (H3) viruses, and type B, A (H3), and A (H1) viruses) in many areas of Japan. In such epidemics a single individual could be co-infected with several influenza viruses. From February to March in 2005, we examined 15 patients who were positive for influenza type A and B viruses when tested with a rapid diagnostic kit. The type A (H3) and B influenza virus genes were successfully amplified by RT-PCR in 10 of the 15 patients, confirming that they were co-infected with type A (H3) and B viruses. The type A (H1) and B virus genes were successfully amplified in another patient, confirming that the patient was co-infected with type A (H1) and B viruses. By contrast, 2 patients were clearly positive for type A and B viruses according to the rapid diagnostic kit, but positive for type B virus alone by RT-PCR. No influenza virus genes were detected by RT-PCR in the remaining 2 patients. To isolate one type from a mixture of two different types of influenza viruses in a specimen, we neutralized one of the types with type-specific antiserum, and isolated the other with MDCK (+) cells. The results obtained by virus isolation were identical to those obtained by RT-PCR. Influenza viruses corresponding to the results of RT-PCR were isolated from 9 of the 11 patients in which isolation was attempted. No viruses were isolated from the 2 patients in whom no virus genes were detectable by RT-PCR. Based on these results we concluded that 11 of 15 patients who were positive for type A and B viruses according to the rapid diagnostic kit were co-infected with type A (H3) or A (H1) and B virus. When several types of influenza viruses are prevalent, as in the 2004/05 influenza season, the possibility of a patient being co-infected with more than one type of influenza virus should be considered.

[Comparison of four rapid diagnostic kits using immunochromatography to detect influenza B viruses].

We compared the usefulness of 4 rapid influenza diagnostic 1-device kits using immunochromatography, which facilitate type differentiation, i.e. ESPLINE Influenza A&B-N (Fujirebio Corp., Japan: ESPLINE), POCTEM INFLUENZA A/B (Sysmex Corp., Japan: POCTEM), Quick Vue Rapid SP influ (Quidel Corp., U.S.A.: Quick Vue), and Capilia Flu A + B (TAUNS Corp., Japan: Capilia), in 278 children in whom influenza infection was suspected in 2004 and 2005. Nasopharyngeal aspirates were diluted for virus isolation and residual samples were centrifuged. Using the supernatant, we conducted rapid diagnosis testing. Influenza virus AH3 was isolated from 40 children, and influenza B virus from 163. Of the 40 children, the sensitivity and specificity of ESPLINE, POCTEM, Quick Vue, and Capilia were 100%/100%, 95%/100%, 98%/96%, and 98%/96%. In the 163 children, the sensitivity and specificity were 89%/100%, 87%/100%, 88%/97%, and 86%/98%. ESPLINE showed the highest sensitivity and specificity to influenza viruses AH3 and B. All kits were less sensitive to influenza B virus than to influenza A virus, however. The specificity of Quick Vue and Capilia was low; so these kits must be improved.

Japanese encephalitis virus in meningitis patients, Japan.

Cerebrospinal fluid specimens from 57 patients diagnosed with meningitis were tested for Japanese encephalitis virus. Total RNA was extracted from the specimens and amplified. Two products had highest homology with Nakayama strain and 2 with Ishikawa strain. Results suggest that Japanese encephalitis virus causes some aseptic meningitis in Japan.

[The clinical features about 5 cases of Japanese encephalitis reported in Japan, 2002].

We discussed the clinical features of 5 Japanese encephalitis (JE) cases which we experienced in 2002. Today there are few opportunities for a clinician to see JE patients. Until the 1950s, the number of JE patients was more than 2000 in Japan, but the annual cases of JE are decreasing remarkably due to the extermination of mosquitoes, thorough vaccination and improvement of environmental sanitation. However, even today the disease still has a high fatality rate. In fact 4 in 5 cases we experienced had poor prognosis and one of them resulted in death despite the relatively early diagnosis. It shows the difficulty of diagnosis and treatment. When we see elderly patients with high fever, headache, and impaired consciousness in late summer and autumn, the important thing is to recognize the possibility of JE. Moreover it turned out that brain MRI and detecting serologic JE virus antibodies was very helpful for diagnosis and treatment. Nowadays we clinicians tend to consider JE as a disease of the past in Japan, however, this experience taught us that it is necessary for us to study JE again and to continue educating the public about it.

[Comparison of three rapid diagnostic kits using immunochromatography for detection of influenza A virsuses].

In 2004, 3 new rapid influenza diagnostic kits using immunochromatography that allow type differentiation became commercially available. They are the ESPLINE Influenza A & B-N (Fujirebio Corp., Japan: ESPLINE-N hereafter), QuickVue Rapid SP influ (Quidel Corp., USA: QuickVue), and POCTEM INFLUENZA A/B (INTERNATIONAL REAGENTS Corp., Japan: POCTEM). The authors performed a prospective study that compared the usefulness among the 3 kits in 151 children with suspected influenza, who were examined within 3 days after onset, between January and March, 2004. Nasopharyngeal aspirates were collected, and viruses were isolated. The residual samples were diluted and centrifuged, and the supernatant was used for the rapid diagnosis tests. Influenza virus AH3 was isolated in 95 children and influenza B virus in 3. In the 95 children with influenza virus AH3, the sensitivity and specificity of ESPLINE-N were 100% and 100%, respectively, those of QuickVue were 99% and 91%, and those of POCTEM were 91% and 100%. The sensitivity of POCTEM was significantly lower than that of the other 2 kits (p < 0.01), and the specificity of QuickVue was significantly lower than that of the other 2 kits (p < 0.05). Examination was performed within 1 day after onset in 55 of the 95 children, including 30 who underwent examination within 6 hours after the development of fever. The body temperature was less than 38.0 degrees C in 14 of the 95 children. In all children including these children, virus detection was possible by ESPLINE-N. ESPLINE-N allowed very accurate diagnosis of influenza A using samples prepared by diluting and centrifuging nasopharyngeal aspirates.

[Incidence and prevalent types of Norwalk virus, Sapporo virus and human astrovirus in pediatric gastroenteritis in Hiroshima Prefecture].

The incidence and prevalent types of Norwalk virus (NV), Sapporo virus (SV), and human astrovirus (HAstV) in pediatric gastroenteritis in Hiroshima Prefecture were investigated in 7 cold seasons, between 1995/96 and 2001/02. The incidences of NV, SV, and HAstV were 23.6% ranging from 16.3 to 34.4, 2.5% ranging from 1.5 to 4.7, and 3.2% ranging from 1.5 to 6.0, respectively. The peak of the incidence of NV was found in November and December. No accumulation of monthly incidence in SV or HAstV was noted. Most NVs detected belonged to genogroup II. A probe type of G2F, according to Fukuda et al., was predominant in NV, followed by G2E and G2B. The probe types of LON and SAP, according to Vinje et al., were predominant in SV. Serotype 1 was predominant in HAstV.