Selection of cellular genetic markers for the detection of infectious poliovirus

AIMS

Cellular responses of an established cell line from human intestinal epithelial cells (INT-407 cells) against poliovirus (PV) infections were investigated in order to find cellular genetic markers for infectious PV detection.

METHODS AND RESULTS

Gene expression profile of INT-407 cells was analysed by DNA microarray technique when cells were infected with poliovirus 1 (PV1) (sabin) at multiplicity of infection of 10^-3 and incubated for 12 h. Poliovirus infection significantly altered the gene expressions of two ion channels, KCNJ4 and SCN7A. The expression profile of KCNJ4 gene was further investigated by real-time RT-qPCR, and it was found that KCNJ4 gene was significantly regulated at 24 h postinfection of PV1.

CONCLUSIONS

KCNJ4 gene, coding a potassium channel protein, is proposed as a cellular genetic marker for infectious PV detection.

SIGNIFICANCE AND IMPACT OF THE STUDY

This is the first study to show the availability of cellular responses to detect infectious PV. The selection of cellular genetic markers for infectious viruses using DNA microarray and RT-qPCR can be applicable for the other enteric viruses.

Effect of sodium-glucose co-transporter-2 inhibitors on impaired ventricular repolarization in people with Type 2 diabetes

AIMS

To test the hypothesis that treatment with a sodium-glucose co-transporter-2 inhibitor would reverse ventricular repolarization heterogeneity, a predictor of cardiovascular mortality, in people with Type 2 diabetes.

METHODS

We retrospectively analysed changes in indices of ventricular repolarization before and after treatment with a sodium-glucose co-transporter-2 inhibitor in 46 people with Type 2 diabetes.

RESULTS

Sodium-glucose co-transporter-2 inhibitor treatment reduced HbA_1c concentration [62±13 mmol/mol (7.7±1.2%) vs 59±16 mmol/mol (7.5±1.4%)], body weight (77.8±13.9 vs 74.7±12.5 kg) and systolic blood pressure (133±18 vs 126±12 mmHg) in the study participants. Heart rate and QTc interval were not changed by sodium-glucose co-transporter-2 inhibitor treatment, but QTc dispersion was significantly reduced (median, 48.8 vs 44.2 ms). Sodium-glucose co-transporter-2 inhibitor treatment reversed QTc dispersion more in participants who had larger QTc dispersion before the treatment. Changes in systolic blood pressure (Spearman's ρ= 0.319; P=0.031), but not in HbA_1c concentration, were correlated with changes in QTc dispersion after sodium-glucose co-transporter-2 inhibitor treatment.

CONCLUSIONS

The findings suggest that sodium-glucose co-transporter-2 inhibitor treatment reverses ventricular repolarization heterogeneity in people with Type 2 diabetes, independently of its effect on glycaemic control. The favourable effect on ventricular repolarization heterogeneity could be the mechanism by which empaglifozin reduced cardiovascular events in a recent study.

In vivo virulence of MHC-adapted AIDS virus serially-passaged through MHC-mismatched hosts

CD8⁺ T-cell responses exert strong suppressive pressure on HIV replication and select for viral escape mutations. Some of these major histocompatibility complex class I (MHC-I)-associated mutations result in reduction of in vitro viral replicative capacity. While these mutations can revert after viral transmission to MHC-I-disparate hosts, recent studies have suggested that these MHC-I-associated mutations accumulate in populations and make viruses less pathogenic in vitro. Here, we directly show an increase in the in vivo virulence of an MHC-I-adapted virus serially-passaged through MHC-I-mismatched hosts in a macaque AIDS model despite a reduction in in vitro viral fitness. The first passage simian immunodeficiency virus (1pSIV) obtained 1 year after SIVmac239 infection in a macaque possessing a protective MHC-I haplotype 90-120-Ia was transmitted into 90-120-Ia^- macaques, whose plasma 1 year post-infection was transmitted into other 90-120-Ia^- macaques to obtain the third passage SIV (3pSIV). Most of the 90-120-Ia-associated mutations selected in 1pSIV did not revert even in 3pSIV. 3pSIV showed lower in vitro viral fitness but induced persistent viremia in 90-120-Ia^- macaques. Remarkably, 3pSIV infection in 90-120-Ia⁺ macaques resulted in significantly higher viral loads and reduced survival compared to wild-type SIVmac239. These results indicate that MHC-I-adapted SIVs serially-transmitted through MHC-I-mismatched hosts can have higher virulence in MHC-I-matched hosts despite their lower in vitro viral fitness. This study suggests that multiply-passaged HIVs could result in loss of HIV-specific CD8⁺ T cell responses in human populations and the in vivo pathogenic potential of these escaped viruses may be enhanced.

CD8⁺ T-cell responses exert considerable control over replication of HIV and select for viral escape mutations. Recent studies have suggested that these major histocompatibility complex class I (MHC-I)-associated mutations accumulate in populations and make viruses less pathogenic in vitro. Other studies have shown that some of these escape mutations can revert after passage to MHC-I-disparate hosts. In an attempt to reconcile these apparently conflicting results, we serially passaged a virus isolate through MHC-I-mismatched hosts in the macaque AIDS model of simian immunodeficiency virus (SIV) infection. Here we show an increase in the in vivo virulence of an MHC-I-adapted virus despite a reduction in in vitro viral replication capacity. Only a few of the selected escape mutations reverted after transmission to MHC-I-disparate recipients. Results clearly showed that MHC-I-adapted SIVs that have been serially-transmitted through MHC-I-mismatched hosts can have higher in vivo virulence in MHC-I-matched hosts despite their lower in vitro viral fitness. This study suggests that HIVs may become less sensitive to CD8⁺ T cell responses and could have increased in vivo virulence by adaptation to MHC-I in human populations.

Hirsutine, an Indole Alkaloid of Uncaria rhynchophylla, Inhibits Late Step in Dengue Virus Lifecycle

Dengue virus (DENV) is transmitted to humans by Aedes mosquitoes and is a public health issue worldwide. No antiviral drugs specific for treating dengue infection are currently available. To identify novel DENV inhibitors, we analyzed a library of 95 compounds and 120 extracts derived from crude drugs (herbal medicines). In the primary screening, A549 cells infected with DENV-1 were cultured in the presence of each compound and extract at a final concentration of 10 μM (compound) and 100 μg/mL (extract), and reduction of viral focus formation was assessed. Next, we eliminated compounds and extracts which were cytotoxic using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Hirsutine, an indole alkaloid of Uncaria rhynchophylla, was identified as a potent anti-DENV compound exhibiting high efficacy and low cytotoxicity. Hirsutine showed antiviral activity against all DENV serotypes. Time-of-drug-addition and time-of-drug-elimination assays indicated that hirsutine inhibits the viral particle assembly, budding, or release step but not the viral translation and replication steps in the DENV lifecycle. A subgenomic replicon system was used to confirm that hirsutine does not restrict viral genome RNA replication. Hirsutine is a novel DENV inhibitor and potential candidate for treating dengue fever.

Proficiency testing with uncertainty evaluation for measuring activities per unit mass of 134Cs and 137Cs in brown rice in Japan

In Japan, we conducted proficiency testing of activity measurement by using high-purity germanium detectors for ¹³⁴Cs and ¹³⁷Cs in brown rice grains. Among 176 reported results, 86 % (for ¹³⁴Cs) and 93 % (for ¹³⁷Cs) of the results satisfied |E_n| ≦ 1. However, 58 reports for ¹³⁴Cs and 51 reports for ¹³⁷Cs had some failures in their evaluations of uncertainties. The proficiency testing was effective to improve the ability of uncertainty evaluation.

A highly pathogenic simian/human immunodeficiency virus effectively produces infectious virions compared with a less pathogenic virus in cell culture

BACKGROUND

The host range of human immunodeficiency virus (HIV) is quite narrow. Therefore, analyzing HIV-1 pathogenesis in vivo has been limited owing to lack of appropriate animal model systems. To overcome this, chimeric simian and human immunodeficiency viruses (SHIVs) that encode HIV-1 Env and are infectious to macaques have been developed and used to investigate the pathogenicity of HIV-1 in vivo. So far, we have many SHIV strains that show different pathogenesis in macaque experiments. However, dynamic aspects of SHIV infection have not been well understood. To fully understand the dynamic properties of SHIVs, we focused on two representative strains-the highly pathogenic SHIV, SHIV-KS661, and the less pathogenic SHIV, SHIV-#64-and measured the time-course of experimental data in cell culture.

METHODS

We infected HSC-F with SHIV-KS661 and -#64 and measured the concentration of Nef-negative (target) and Nef-positive (infected) HSC-F cells, the total viral load, and the infectious viral load daily for 9 days. The experiments were repeated at two different multiplicities of infection, and a previously developed mathematical model incorporating the infectious and non-infectious viruses was fitted to the full dataset of each strain simultaneously to characterize the infection dynamics of these two strains.

RESULTS AND CONCLUSIONS

We quantified virological indices including virus burst sizes and basic reproduction number of both SHIV-KS661 and -#64. Comparing the burst size of total and infectious viruses (viral RNA copies and TCID₅₀, respectively), we found that there was a statistically significant difference between the infectious virus burst size of SHIV-KS661 and -#64, while there was no significant difference between the total virus burst size. Furthermore, our analyses showed that the fraction of infectious virus among the produced SHIV-KS661 viruses, which is defined as the infectious viral load (TCID₅₀/ml) divided by the total viral load (RNA copies/ml), is more than 10-fold higher than that of SHIV-#64 during overall infection (i.e., for 9 days). Taken together, we conclude that the highly pathogenic SHIV produces infectious virions more effectively than the less pathogenic SHIV in cell culture.

Duration of SHIV production by infected cells is not exponentially distributed: Implications for estimates of infection parameters and antiviral efficacy

The duration of the eclipse phase, from cell infection to the production and release of the first virion progeny, immediately followed by the virus-production phase, from the first to the last virion progeny, are important steps in a viral infection, by setting the pace of infection progression and modulating the response to antiviral therapy. Using a mathematical model (MM) and data for the infection of HSC-F cells with SHIV in vitro, we reconfirm our earlier finding that the eclipse phase duration follows a fat-tailed distribution, lasting 19 h (18–20 h). Most importantly, for the first time, we show that the virus-producing phase duration, which lasts 11 h (9.8–12 h), follows a normal-like distribution, and not an exponential distribution as is typically assumed. We explore the significance of this finding and its impact on analysis of plasma viral load decays in HIV patients under antiviral therapy. We find that incorrect assumptions about the eclipse and virus-producing phase distributions can lead to an overestimation of antiviral efficacy. Additionally, our predictions for the rate of plasma HIV decay under integrase inhibitor therapy offer an opportunity to confirm whether HIV production duration in vivo also follows a normal distribution, as demonstrated here for SHIV infections in vitro.

Prolonged Negative Pressure Wound Therapy Followed by Split-Thickness Skin Graft Placement for Wide Dehiscence of Clamshell Incision After Bilateral Lung Transplantation: A Case Report

Clamshell incision is a standard approach for bilateral lung transplantation, providing a good operative field; however, once wide dehiscence occurs, its management is sometimes difficult because of intense immunosuppression and malnutrition of the recipient. A 22-year-old man with idiopathic pulmonary arterial hypertension underwent cadaveric bilateral lung transplantation through a clamshell incision using standard cardiopulmonary bypass. He developed wound dehiscence on postoperative day (POD) 20 that resulted in exposure of the bilateral fifth ribs and open pneumothorax. Considering the extreme malnutrition and emaciation of the recipient, we avoided initial closure of the dehiscence. After the debridement of necrotic tissue, negative pressure wound therapy was initiated on POD 25 and was continued for approximately 6 months with trafermin spray application. Eventually, the wound, including the fifth ribs, was completely covered with granulation tissue except for the wire tying the sternum. On POD 217, the patient underwent removal of the sternal wire followed by split-thickness skin grafting. His wound was successfully closed and he was discharged without activity limitation on POD 265.

Diagnostic Value of Brain Calcifications in Adult-Onset Leukoencephalopathy with Axonal Spheroids and Pigmented Glia

Adult-onset leukoencephalopathy with axonal spheroids and pigmented glia is a rare neurodegenerative disease resulting from mutations in the colony stimulating factor 1 receptor gene. Accurate diagnosis can be difficult because the associated clinical and MR imaging findings are nonspecific. We present 9 cases with intracranial calcifications distributed in 2 brain regions: the frontal white matter adjacent to the anterior horns of the lateral ventricles and the parietal subcortical white matter. Thin-section (1-mm) CT scans are particularly helpful in detection due to the small size of the calcifications. These calcifications had a symmetric "stepping stone appearance" in the frontal pericallosal regions, which was clearly visible on reconstructed sagittal CT images. Intrafamilial variability was seen in 2 of the families, and calcifications were seen at birth in a single individual. These characteristic calcification patterns may assist in making a correct diagnosis and may contribute to understanding of the pathogenesis of leukoencephalopathy.