Human norovirus cultivation systems and their use in antiviral research.

Human norovirus (HuNoV) is a major cause of acute gastroenteritis and foodborne diseases, affecting all age groups. Despite its clinical needs, no approved antiviral therapies are available. Since the discovery of HuNoV in 1972, studies on anti-norovirals, mechanism of HuNoV infection, viral inactivation, etc., have been hampered by the lack of a robust laboratory-based cultivation system for HuNoV. A recent breakthrough in the development of HuNoV cultivation systems has opened opportunities for researchers to investigate HuNoV biology in the context of de novo HuNoV infections. A tissue stem cell-derived human intestinal organoid/enteroid (HIO) culture system is one of those that supports HuNoV replication reproducibly and, to our knowledge, is most widely distributed to laboratories worldwide to study HuNoV and develop therapeutic strategies. This review summarizes recently developed HuNoV cultivation systems, including HIO, and their use in antiviral studies.

Interstitial lung disease caused by niraparib in ovarian cancer patient: a case report and literature review.

Drug-induced interstitial lung disease (DIILD) is one of the most common and important adverse drug reactions. Still, the details of the clinical presentation of DIILD caused by poly (adenosine diphosphate-ribose) polymerase (PARP) inhibitors are unknown. A 73-year-old Japanese woman was started on niraparib maintenance therapy after radical surgery and adjuvant chemotherapy for high-grade serous carcinoma originating from the fallopian tube. Forty-seven days after starting niraparib, she presented to the hospital with dyspnea and was diagnosed with DIILD caused by niraparib. The drug was discontinued, and the patient was treated with steroid pulse therapy, and her condition improved. In clinical trials of PARP inhibitors, DIILD was reported in 0.13% of patients with olaparib, but no DIILDs, including pneumonia or pneumonitis, were reported in any patient with niraparib. This is the first report of DIILD caused by niraparib worldwide. In the future, the frequency of DIILD caused by niraparib should be clarified in real-world data.

Inhibitory effect of Ephedra herba on human norovirus infection in human intestinal organoids.

Human norovirus (HuNoV) is a major cause of acute gastroenteritis and foodborne diseases worldwide with public health concern, yet no antiviral therapies have been developed. In this study, we aimed to screen crude drugs, which are components of Japanese traditional medicine, ''Kampo'' to see their effects on HuNoV infection using a reproducible HuNoV cultivation system, stem-cell derived human intestinal organoids/enteroids (HIOs). Among the 22 crude drugs tested, Ephedra herba significantly inhibited HuNoV infection in HIOs. A time-of-drug addition experiment suggested that this crude drug more preferentially targets post-entry step than entry step for the inhibition. To our knowledge, this is the first anti-HuNoV inhibitor screen targeting crude drugs, and Ephedra herba was identified as a novel inhibitor candidate that merits further study.

Atomic Structure of the Human Sapovirus Capsid Reveals a Unique Capsid Protein Conformation in Caliciviruses.

Sapovirus (SaV) is a member of the Caliciviridae family, which causes acute gastroenteritis in humans and animals. Human sapoviruses (HuSaVs) are genetically and antigenically diverse, but the lack of a viral replication system and structural information has hampered the development of vaccines and therapeutics. Here, we successfully produced a self-assembled virus-like particle (VLP) from the HuSaV GI.6 VP1 protein, and the first atomic structure was determined using single-particle cryo-electron microscopy (cryo-EM) at a 2.9-Å resolution. The atomic model of the VP1 protein revealed a unique capsid protein conformation in caliciviruses. All N-terminal arms in the A, B, and C subunits interacted with adjacent shell domains after extending through their subunits. The roof of the arched VP1 dimer was formed between the P2 subdomains by the interconnected ß strands and loops, and its buried surface was minimized compared to those of other caliciviruses. Four hypervariable regions that are potentially involved in the antigenic diversity of SaV formed extensive clusters on top of the P domain. Potential receptor binding regions implied by tissue culture mutants of porcine SaV were also located near these hypervariable clusters. Conserved sequence motifs of the VP1 protein, "PPG" and "GWS," may stabilize the inner capsid shell and the outer protruding domain, respectively. These findings will provide the structural basis for the medical treatment of HuSaV infections and facilitate the development of vaccines, antivirals, and diagnostic systems. IMPORTANCE SaV and norovirus, belonging to the Caliciviridae family, are common causes of acute gastroenteritis in humans and animals. SaV and norovirus infections are public health problems in all age groups, which occur explosively and sporadically worldwide. HuSaV is genetically and antigenically diverse and is currently classified into 4 genogroups consisting of 18 genotypes based on the sequence similarity of the VP1 proteins. Despite these detailed genetic analyses, the lack of structural information on viral capsids has become a problem for the development of vaccines or antiviral drugs. The 2.9-Å atomic model of the HuSaV GI.6 VLP presented here not only revealed the location of the amino acid residues involved in immune responses and potential receptor binding sites but also provided essential information for the design of stable constructs needed for the development of vaccines and antivirals.

Uterine angioleiomyoma with disseminated intravascular coagulation: a case report.

BACKGROUND: Uterine angioleiomyoma is benign tumor that composed of smooth muscle cells and thick-walled vessels. It is a very rare condition reported to present as lower abdominal mass, accompanied by dysmenorrhea and hypermenorrhea. However, its clinical presentation is not known. CASE PRESENTATION: We report the case of a 44-year-old Japanese woman who developed severe anemia with disseminated intravascular coagulation without obvious external bleeding. The patient had a huge abdominal mass of over 20 cm in size, which was thought to be a uterine tumor. She received daily blood transfusions and her condition improved rapidly after she underwent hysterectomy. Pathological examination of the tumor revealed spindle-shaped cells with little atypia and mitosis, and numerous large vessels with smooth muscle and thrombus in the vessels. CONCLUSIONS: Uterine angioleiomyoma was identified as the cause of the coagulation abnormality. CCND2 and AR gene amplification was detected in the tumor. Uterine tumors that present with coagulopathy despite a clinical course suggestive of benign disease should undergo differential diagnosis for uterine angioleiomyoma.

Bile acids and ceramide overcome the entry restriction for GII.3 human norovirus replication in human intestinal enteroids.

Human noroviruses (HuNoVs) cause sporadic and epidemic outbreaks of gastroenteritis in all age groups worldwide. We previously reported that stem cell-derived human intestinal enteroid (HIE) cultures support replication of multiple HuNoV strains and that some strains (e.g., GII.3) replicate only in the presence of bile. Heat- and trypsin-treatment of bile did not reduce GII.3 replication, indicating a nonproteinaceous component in bile functions as an active factor. Here we show that bile acids (BAs) are critical for GII.3 replication and replication correlates with BA hydrophobicity. Using the highly effective BA, glycochenodeoxycholic acid (GCDCA), we show BAs act during the early stage of infection, BA-dependent replication in HIEs is not mediated by detergent effects or classic farnesoid X receptor or Takeda G protein-coupled receptor 5 signaling but involves another G protein-coupled receptor, sphingosine-1-phosphate receptor 2, and BA treatment of HIEs increases particle uptake. We also demonstrate that GCDCA induces multiple cellular responses that promote GII.3 replication in HIEs, including enhancement of 1) endosomal uptake, 2) endosomal acidification and subsequent activity of endosomal/lysosomal enzyme acid sphingomyelinase (ASM), and 3) ceramide levels on the apical membrane. Inhibitors of endosomal acidification or ASM reduce GII.3 infection and exogenous addition of ceramide alone permits infection. Furthermore, inhibition of lysosomal exocytosis of ASM, which is required for ceramide production at the apical surface, decreases GII.3 infection. Together, our results support a model where GII.3 exploits rapid BA-mediated cellular endolysosomal dynamic changes and cellular ceramide to enter and replicate in jejunal HIEs.

Dynamic rotation of the protruding domain enhances the infectivity of norovirus.

Norovirus is the major cause of epidemic nonbacterial gastroenteritis worldwide. Lack of structural information on infection and replication mechanisms hampers the development of effective vaccines and remedies. Here, using cryo-electron microscopy, we show that the capsid structure of murine noroviruses changes in response to aqueous conditions. By twisting the flexible hinge connecting two domains, the protruding (P) domain reversibly rises off the shell (S) domain in solutions of higher pH, but rests on the S domain in solutions of lower pH. Metal ions help to stabilize the resting conformation in this process. Furthermore, in the resting conformation, the cellular receptor CD300lf is readily accessible, and thus infection efficiency is significantly enhanced. Two similar P domain conformations were also found simultaneously in the human norovirus GII.3 capsid, although the mechanism of the conformational change is not yet clear. These results provide new insights into the mechanisms of non-enveloped norovirus transmission that invades host cells, replicates, and sometimes escapes the hosts immune system, through dramatic environmental changes in the gastrointestinal tract.

Frequent PIK3CA mutations in eutopic endometrium of patients with ovarian clear cell carcinoma.

Recent studies have reported cancer-associated mutations in normal endometrium. Mutations in eutopic endometrium may lead to endometriosis and endometriosis-associated ovarian cancer. We investigated PIK3CA mutations (PIK3CAm) for three hotspots (E542K, E545K, H1047R) in eutopic endometrium in patients with ovarian cancer and endometriosis from formalin-fixed paraffin-embedded specimens by laser-capture microdissection and droplet digital PCR. The presence of PIK3CAm in eutopic endometrial glands with mutant allele frequency ≥ 15% were as follows: ovarian clear cell carcinoma (OCCC) with PIK3CAm in tumors, 20/300 hotspots in 11/14 cases; OCCC without PIK3CAm, 42/78 hotspots in 11/12 cases; high-grade serous ovarian carcinoma, 8/45 hotspots in 3/5 cases; and endometriotic cysts, 5/63 hotspots in 5/6 cases. These rates were more frequent than in noncancer nonendometriosis controls (7/309 hotspots in 5/17 cases). In OCCC without PIK3CAm, 7/12 (58%) cases showed multiple hotspot mutations in the same eutopic endometrial glands. In 3/54 (5.6%) cases, PIK3CAm was found in eutopic endometrial stroma. Multisampling of the OCCC tumors with PIK3CAm showed intratumor heterogeneity in three of eight cases. In two cases, PIK3CAm was detected in the stromal component of the tumor. Homogenous PIK3CAm in the epithelial component of the tumor matched the mutation in eutopic endometrial glands in only one case. Eutopic endometrial glands in ovarian cancer and endometriosis show high frequency of PIK3CAm that is not consistent with tumors, and multiple hotspot mutations are often found in the same glands. While the mutations identified in eutopic endometrium may not be driver mutations in the patient's cancer, these are still driver mutations but this specific clone has not undergone the requisite steps for the development of cancer.

Ovarian cyst elevation using a metreurynter for laparoscopic cystectomy of a benign ovarian cyst during pregnancy.

BACKGROUND: A uterine manipulator cannot be used to elevate the ovary in benign ovarian surgery during pregnancy. This report describes our method of elevation of the ovary using a metreurynter with the success rate of the procedure and a comparison of surgical results and pregnancy outcomes between the successful and unsuccessful cases. METHODS: Between August 2003 and February 2020, 11 pregnant patients with a tumor found sunk in the Cul-de-sac underwent laparoscopic cystectomy for a benign ovarian cyst with a metreurynter. The surgical results, success and failure of the elevation by a metreurynter, pregnancy outcomes, and fetal status at delivery were evaluated. RESULTS: Elevation of ovarian tumors with a metreurynter was successful in nine cases. However, it was unsuccessful in the remaining two cases wherein the ovary was lifted with forceps while the uterus was in a compressed state. The operative time was also longer in these cases. The pregnancy prognosis, however, was good for both, successful and unsuccessful cases. CONCLUSIONS: The metreurynter is an inexpensive and practical obstetric device, and its optimal use allows the performance of a procedure with minimal burden on a pregnant uterus. Therefore, we recommend the appropriate use of this method to enable effective laparoscopic cystectomy of ovarian tumors during pregnancy.

A case report of bladder and intestinal endometriosis, and the relationship between sex hormone receptor expression and PIK3CA mutation analysis.

BACKGROUND: Extragonadal endometriosis is a rare condition, and its disease manifestation and long-term prognosis have not been elucidated. We report an extragonadal endometriosis case controlled by drug therapy for 14 years with analysis of the sex hormone receptor expression and PIK3CA mutation. CASE PRESENTATION: The patient was diagnosed with bladder endometriosis at age of 30 years, and underwent bilateral nephrostomy and GnRHa therapy with add-back therapy. The patient was switched to dienogest therapy at age 35 and had hematuria and bloody stools at age 38. PET-CT revealed a 6-cm mass in the bladder with fluorodeoxyglucose accumulation and the diagnosis of endometriosis in the bladder, sigmoid colon, and cecum was confirmed after the biopsy result. The lesion's tubular structures were positive for the estrogen receptor, but only 30% positive for the progesterone receptor, and the H1047R mutation in PIK3CA was found in tubular structures of the bladder lesion. GnRHa therapy caused the tumors to shrink. CONCLUSION: Decreased progesterone receptor expression and oncogenic mutations may influence the course of less common and rare site endometriosis. Rare site endometriosis often requires long-term hormone therapy, and management should be tailored to the patient's life stage, keeping in mind complications, such as decreased bone density.

Characterization of patients that can continue conservative treatment for adenomyosis.

BACKGROUND: Historically, hysterectomy has been the radical treatment for adenomyosis. Although, some patients may not want to have their uterus removed, patients often have to no choice but to request hysterectomy during conservative treatment. The factors necessitating these hysterectomies remain unknown. The purpose of this study was to determine which patients can continue conservative treatment for adenomyosis. METHODS: We selected women diagnosed with adenomyosis and provided with conservative treatment at the Kindai University Hospital and Osaka Red Cross Hospital in Osaka Japan from 2008 to 2017. Age at diagnosis, parity, uterine size, subtype of adenomyosis, type of conservative treatment, and timing of hysterectomy for cases with difficulty continuing conservative treatment were examined retrospectively. RESULTS: A total of 885 patients were diagnosed with adenomyosis, and 124 started conservative treatment. Conservative treatment was continued in 96 patients (77.4%) and hysterectomy was required in 28 patients (22.6%). The cumulative hysterectomy rate was 32.4%, and all women had hysterectomy within 63 months. In the classification tree, 82% (23/28) of women aged 46 years or younger were able to continue conservative treatment when parity was zero or one. In those with parity two and over, 95% (20/21) of those aged 39 years and older had hysterectomy. CONCLUSIONS: Patients who continue conservative treatment for approximately 5 years are more likely to have successful preservation of the uterus. Multiparity and higher age at diagnosis are factors that contribute to hysterectomy after conservative treatment. Parity and age at diagnosis may be stratifying factors in future clinical trials of hormone therapy.

Research Article Quality of life after laparoscopic hysterectomy versus abdominal hysterectomy.

BACKGROUND: Laparoscopic surgery has been described as a minimally invasive surgery. The purpose of this study is to clarify its minimal invasive features using a patient questionnaire on the postoperative quality of life (QOL) over various time periods following either laparoscopic hysterectomy (LH) or abdominal hysterectomy (AH) and to compare the results. METHODS: This study enrolled 28 patients who underwent total hysterectomy for uterine fibroids in 2012 (14 AH cases and 24 LH cases) were enrolled in this study. The 36-Item Short Form Survey (SF-36) questionnaire was completed on postsurgical day 3; weeks 1, 2, and 4; and month 6. The results were compared between the two groups. RESULTS: Patients who underwent LH scored significantly higher on physical functioning on postoperative day 3 and week 2; physical role and bodily pain on day 3 and week 1; general health on postoperative day 3, weeks 1, 2, and 4, and month 6; social functioning on day 3; and emotional role on day 3 and week 1. No significant differences were found between vitality and mental health at any time point or in the categories above at any other time point. CONCLUSIONS: Postoperative QOL in LH cases was improved on day 3 and week 1; however, no significant differences between the LH and AH groups were found in most categories at week 4 and month 6. LH leads to superior short-term QOL early in the postoperative period relative to AH.

Management Strategies for Brain Tumors Diagnosed during Pregnancy: A Case Report and Literature Review.

Background and Objectives: Maternal brain tumors diagnosed during pregnancy are very rare, and their clinical course remains incompletely understood. We recently experienced a case of a brain tumor diagnosed at 30 weeks of gestation, and the treatment was initiated after delivery at 32 weeks of gestation. In this study, we reviewed case reports of brain tumors diagnosed during pregnancy, focusing on whether the brain tumor was treated during pregnancy or after termination of pregnancy and on the timing of therapeutic intervention. Materials and Methods: We searched PubMed and Ichushi-Web for articles published after January 2000 that reported cases of maternal brain tumors diagnosed during pregnancy. The patients were divided into two groups according to whether the tumor was treated during pregnancy (Group A) or after termination of pregnancy (Group B). Results: In total, 42 patients were included in the study (13 (31%) in Group A and 29 (69%) in Group B). The most common symptoms before diagnosis were those caused by increased intracranial pressure (57.1%). The diagnosis was made at 18 ± 6 weeks of gestation in Group A and 26 ± 9 weeks of gestation in Group B (p = 0.007). In all cases diagnosed after 34 weeks of gestation, termination of pregnancy was followed by treatment. Treatment was initiated within two weeks of diagnosis in 50% of patients in Group A and 30% in Group B. Conclusions: When severe symptoms caused by increased intracranial pressure last for several weeks, imaging tests should be considered. Termination of pregnancy is a good option for a brain tumor diagnosed after 34 weeks of gestation, while comprehensive treatment decisions should be made based on the severity of symptoms and the course of pregnancy in other cases.

Intratumor heterogeneity and homologous recombination deficiency of high-grade serous ovarian cancer are associated with prognosis and molecular subtype and change in treatment course.

OBJECTIVE: High-grade serous ovarian cancers (HGSOC) are genomically characterized by homologous recombination deficiency (HRD) and TP53 mutations, which lead to intratumor heterogeneity (ITH). This study aimed to reveal the relationship between HRD, ITH and prognosis and analyze their changes during treatment. METHODS: We obtained 573 SNP array and gene expression array data from The Cancer Genome Atlas. SNP array data were processed to calculate the Clonality Index (CI) and loss of heterozygosity (LOH) scores. Gene expression array data were used for classifying molecular subtypes. Additionally, we obtained 33 samples from 20 HGSOC patients, including 4 samples from interval debulking surgery (IDS) and 9 samples from recurrent surgery. RESULTS: We divided HGSOC samples into 2 groups. The high CI group showed a high recurrent risk, and the high LOH group showed a statistically good prognosis. Combining the two factors, the high LOH/low CI group showed a statistically good prognosis. In terms of molecular subtypes, the mesenchymal subtype, which had a poor prognosis, showed a high CI with statisitically significant difference and the immunoreactive subtype, which had a good prognosis, showed a tendency to have a high LOH score. Throughout treatment, the CI decreased to one at the IDS (n = 4) and then increased at recurrence (n = 3). LOH scores greatly decreased in two cases at the IDS. CONCLUSIONS: ITH and HRD were associated with prognosis in HGSOC. ITH decreased after neoadjuvant chemotherapy, suggesting that the chemo-resistant cancer clone remains after chemotherapy.

Endometriosis-associated ovarian cancer occurs early during follow-up of endometrial cysts.

BACKGROUND: Endometriosis is a risk factor for ovarian cancer. Endometriosis-associated ovarian cancer (EAOC), most commonly clear cell carcinoma, is believed to develop from ovarian endometrial cysts. In this study, we reviewed published cases of EAOC considered to have developed from endometrial cysts, and focused on the observation period. METHODS: We searched for articles published since January 2000 that reported cases of ovarian cancer thought to have originated from endometrial cysts using PubMed, Web of Science, and Ichushi-Web. The period from the start of follow-up of the endometrial cyst to the diagnosis of ovarian cancer was calculated. RESULTS: Seventy-nine cases were identified from 32 articles. The median period from the diagnosis of endometrial cysts to the diagnosis of ovarian cancer was only 36 months. Approximately 75% of cases developed into cancer within 60 months and most cases developed within 120 months. CONCLUSION: Our results suggest that clinically detectable cysts subsequently diagnosed as ovarian cancer might already have contained cancer cells. Therefore, the mechanism of EAOC development needs to be re-examined and appropriate management guidelines need to be developed.

Changes of tight junction and interleukin-8 expression using a human gastroid monolayer model of Helicobacter pylori infection.

BACKGROUND: Lack of a model that mirrors Helicobacter pylori-induced gastric mucosal inflammation has hampered investigation of early host-bacterial interactions. We used an ex vivo model of human stomach, gastric epithelial organoid monolayers (gastroid monolayers) to investigate interactions of H pylori infection and the apical junctional complex and interleukin-8 (IL-8) expression. METHOD: Morphology of human antral mucosal gastroid monolayers was evaluated using histology, immunohistochemical (IHC) staining, and transmission electron microscopy (TEM). Functional and gross changes in the apical junctional complexes were assessed using transepithelial electrical resistance (TEER), cytotoxicity assays, and confocal laser scanning microscopy. IL-8 expression was evaluated by real-time quantitative PCR and ELISA. RESULTS: When evaluated by IHC and TEM, the morphology of gastroid monolayers closely resembled in vivo human stomach. Following inoculation of H pylori, TEER transiently declined (up to 51%) in an H pylori density-dependent manner. TEER recovered by 48 hours post-infection and remained normal despite continued presence and replication of H pylori. Confocal scanning microscopy showed minimal disruption of zonula occludens-1 or E-cadherin structure. IL-8 production was unchanged by infection with either CagA-positive or CagA-negative H pylori and JNK and MEK inhibitors did not suppress IL-8 production, whereas p38 and IKK inhibitor significantly did. CONCLUSION: Human gastroid monolayers provide a model for experimental H pylori infection more consistent with in vivo human infections than seen with typical gastric epithelial cell lines. This ex vivo system should lead to better understanding of H pylori host-pathogen interactions.

Functional receptor molecules CD300lf and CD300ld within the CD300 family enable murine noroviruses to infect cells.

Norovirus is the leading cause of acute gastroenteritis worldwide. Since the discovery of human norovirus (HuNoV), an efficient and reproducible norovirus replication system has not been established in cultured cells. Although limited amounts of virus particles can be produced when the HuNoV genome is directly transfected into cells, the HuNoV cycle of infection has not been successfully reproduced in any currently available cell-culture system. Those results imply that the identification of a functional cell-surface receptor for norovirus might be the key to establishing a norovirus culture system. Using a genome-wide CRISPR/Cas9 guide RNA library, we identified murine CD300lf and CD300ld as functional receptors for murine norovirus (MNV). The treatment of susceptible cells with polyclonal antibody against CD300lf significantly reduced the production of viral progeny. Additionally, ectopic CD300lf expression in nonsusceptible cell lines derived from other animal species enabled MNV infection and progeny production, suggesting that CD300lf has potential for dictating MNV host tropism. Furthermore, CD300ld, which has an amino acid sequence in the N-terminal region of its extracellular domain that is highly homologous to that of CD300lf, also functions as a receptor for MNV. Our results indicate that direct interaction of MNV with two cell-surface molecules, CD300lf and CD300ld, dictates permissive noroviral infection.

Efficacy of weekly administration of paclitaxel and carboplatin for advanced ovarian cancer patients with poor performance status.

OBJECTIVE: The aim of this study was to reveal the efficacy of weekly administration of paclitaxel and carboplatin for advanced ovarian cancer patients with poor performance status (PS). METHODS: FIGO stage III/IV ovarian cancer or fallopian tube cancer patients who underwent interval debulking surgery (IDS) followed by neoadjuvant chemotherapy (NAC) were analyzed retrospectively. Patients were divided into two groups based on NAC: weekly paclitaxel and carboplatin (W-TC) and 3 weeks of paclitaxel and carboplatin (TW-TC). Toxicity, efficacy of NAC, surgery outcome, and prognosis were assessed by comparing the two groups. RESULTS: Twenty patients treated with W-TC and 18 patients treated with TW-TC were analyzed. All of the W-TC patients were poor PS (PS ≥ 2), and all of the TW-TC patients were good PS (PS ≤ 1). The overall clinical response rates were 70% in W-TC and 83.4% in TW-TC. In the W-TC group, Grade 3/4 anemia and thrombocytopenia and greater than grade 2 neuropathy were significantly reduced compared to TW-TC patients. A frequency of treatment delay greater than 7 and 14 days, G-CSF support, blood transfusion, and dose reduction or regimen change were also significantly reduced in the W-TC group. The rate of IDS, optimal debulking surgery, complications during operation, and blood transfusion were similar between the W-TC and TW-TC groups. Progression-free survival and overall survival were also similar between the two groups. CONCLUSION: Our study suggested that NAC with W-TC for poor PS patients with non-treated ovarian cancer reduced the toxicity of chemotherapy and had the same efficacy as TW-TC.

Evaluation of the use of various rat strains for immunogenic potency tests of Sabin-derived inactivated polio vaccines.

Slc:Wistar rats have been the only strain used in Japan for purpose of evaluating a national reference vaccine for the Sabin-derived inactivated polio vaccine (sIPV) and the immunogenicity of sIPV-containing products. However, following the discovery that the Slc:Wistar strain was genetically related to the Fischer 344 strain, other "real" Wistar strains, such as Crlj:WI, that are available worldwide were tested in terms of their usefulness in evaluating the immunogenicity of the past and current lots of a national reference vaccine. The response of the Crlj:WI rats against the serotype 1 of sIPV was comparable to that of the Slc:Wistar rats, while the Crlj:WI rats exhibited a higher level of response against the serotypes 2 and 3. The immunogenic potency units of a national reference vaccine determined using the Slc:Wistar rats were reproduced on tests using the Crlj:WI rats. These results indicate that a titer of the neutralizing antibody obtained in response to a given dose of sIPV cannot be directly compared between these two rat strains, but that, more importantly, the potency units are almost equivalent for the two rat strains.

Replication of Human Norovirus RNA in Mammalian Cells Reveals Lack of Interferon Response.

UNLABELLED: Human noroviruses (HuNoVs), named after the prototype strain Norwalk virus (NV), are a leading cause of acute gastroenteritis outbreaks worldwide. Studies on the related murine norovirus (MNV) have demonstrated the importance of an interferon (IFN) response in host control of virus replication, but this remains unclear for HuNoVs. Despite the lack of an efficient cell culture infection system, transfection of stool-isolated NV RNA into mammalian cells leads to viral RNA replication and virus production. Using this system, we show here that NV RNA replication is sensitive to type I (α/ß) and III (interleukin-29 [IL-29]) IFN treatment. However, in cells capable of a strong IFN response to Sendai virus (SeV) and poly(I·C), NV RNA replicates efficiently and generates double-stranded RNA without inducing a detectable IFN response. Replication of HuNoV genogroup GII.3 strain U201 RNA, generated from a reverse genetics system, also does not induce an IFN response. Consistent with a lack of IFN induction, NV RNA replication is enhanced neither by neutralization of type I/III IFNs through neutralizing antibodies or the soluble IFN decoy receptor B18R nor by short hairpin RNA (shRNA) knockdown of mitochondrial antiviral signaling protein (MAVS) or interferon regulatory factor 3 (IRF3) in the IFN induction pathways. In contrast to other positive-strand RNA viruses that block IFN induction by targeting MAVS for degradation, MAVS is not degraded in NV RNA-replicating cells, and an SeV-induced IFN response is not blocked. Together, these results indicate that HuNoV RNA replication in mammalian cells does not induce an IFN response, suggesting that the epithelial IFN response may play a limited role in host restriction of HuNoV replication. IMPORTANCE: Human noroviruses (HuNoVs) are a leading cause of epidemic gastroenteritis worldwide. Due to lack of an efficient cell culture system and robust small-animal model, little is known about the innate host defense to these viruses. Studies on murine norovirus (MNV) have shown the importance of an interferon (IFN) response in host control of MNV replication, but this remains unclear for HuNoVs. Here, we investigated the IFN response to HuNoV RNA replication in mammalian cells using Norwalk virus stool RNA transfection, a reverse genetics system, IFN neutralization reagents, and shRNA knockdown methods. Our results show that HuNoV RNA replication in mammalian epithelial cells does not induce an IFN response, nor can it be enhanced by blocking the IFN response. These results suggest a limited role of the epithelial IFN response in host control of HuNoV RNA replication, providing important insights into our understanding of the host defense to HuNoVs that differs from that to MNV.