Translation Driven by Picornavirus IRES Is Hampered from Sindbis Virus Replicons: Rescue by Poliovirus 2A Protease

Alphavirus replicons are very useful for analyzing different aspects of viral molecular biology. They are also useful tools in the development of new vaccines and highly efficient expression of heterologous genes. We have investigated the translatability of Sindbis virus (SV) subgenomic mRNA bearing different 5′-untranslated regions, including several viral internal ribosome entry sites (IRESs) from picornaviruses, hepatitis C virus, and cricket paralysis virus. Our findings indicate that all these IRES-containing mRNAs are initially translated in culture cells transfected with the corresponding SV replicon but their translation is inhibited in the late phase of SV replication. Notably, co-expression of different poliovirus (PV) non-structural genes reveals that the protease 2A (2A^pro) is able to increase translation of subgenomic mRNAs containing the PV or encephalomyocarditis virus IRESs but not of those of hepatitis C virus or cricket paralysis virus. A PV 2A^pro variant deficient in eukaryotic initiation factor (eIF) 4GI cleavage or PV protease 3C, neither of which cleaves eIF4GI, does not increase picornavirus IRES-driven translation, whereas L protease from foot-and-mouth disease virus also rescues translation. These findings suggest that the replicative foci of SV-infected cells where translation takes place are deficient in components necessary to translate IRES-containing mRNAs. In the case of picornavirus IRESs, cleavage of eIF4GI accomplished by PV 2A^pro or foot-and-mouth disease virus protease L rescues this inhibition. eIF4GI co-localizes with ribosomes both in cells electroporated with SV replicons bearing the picornavirus IRES and in cells co-electroporated with replicons that express PV 2A^pro. These findings support the idea that eIF4GI cleavage is necessary to rescue the translation driven by picornavirus IRESs in baby hamster kidney cells that express SV replicons.     

Fragment-based identification and optimization of a class of potent pyrrolo[2,1-f][1,2,4]triazine MAP4K4 inhibitors

MAP4K4 has been shown to regulate key cellular processes that are tied to disease pathogenesis. In an effort to generate small molecule MAP4K4 inhibitors, a fragment-based screen was carried out and a pyrrolotriazine fragment with excellent ligand efficiency was identified. Further modification of this fragment guided by X-ray crystal structures and molecular modeling led to the discovery of a series of promising compounds with good structural diversity and physicochemical properties. These compounds exhibited single digit nanomolar potency and compounds 35 and 44 achieved good in vivo exposure.     

Synthesis and in vitro antiviral activities of 3′-fluoro (or chloro) and 2′,3′-difluoro 2′,3′-dideoxynucleoside analogs against hepatitis B and C viruses

Chronic infections with hepatitis B virus (HBV) and hepatitis C virus (HCV) lead to serious liver diseases worldwide. Co-infection with HBV and HCV is very common and is associated with increased risk of liver pathogenesis, liver cancer, and liver failure. Several 5-substituted 3′-fluoro (or chloro) (1–4, 6, 7, 17–19) and 2′,3′-difluoro 2′,3′-dideoxynucleosides (15 and 16) were synthesized and evaluated for in vitro antiviral activities against duck hepatitis B virus (DHBV), human hepatitis B virus, and hepatitis C virus. Of these compounds 4, 7, 17, and 19 demonstrated moderate anti-HBV activity, and 2, 4, 7, 8, and 19 were weak inhibitors of HCV. Although 5-iodo derivative (7) was most inhibitory against HCV, it exhibited a reduction in cellular RNA levels in Huh-7 cells. The 5-hydroxymethyl-3′-fluoro-2′,3′-dideoxyuridine (4) and 1-(3-chloro-2,3-dideoxy-β-d-erythro-pentofuranosyl)-5-fluorouracil (19) provided the most inhibition of both viruses without cytotoxicity.     

Noninvasive Assessment of Gastrointestinal Parasite Infections in Free-Ranging Primates

Recent evidence of emerging human diseases with origins or likely transmission to humans, or both, that involve primates and a greater recognition of the risk of human pathogen transmission to free-ranging primates have raised awareness of the potential impact of zoonotic pathogen transmission on primate conservation and nonhuman primate and human health. As human population density continues to increase exponentially, speeding the reduction and fragmentation of primate habitats, greater human-primate contact is inevitable and even higher rates of pathogen transmission are likely. Thus interest has grown in collecting baseline data on patterns of parasitic infections in wild primate populations to provide an index of population health and to begin to assess and, to manage disease risks. Primatologists traditionally have been involved with such surveys through noninvasive assessment of gastrointestinal parasites. Unfortunately, previous studies have tended toward divergent methodologies, compromising the potential for longitudinal and comparative work. Here, I provide practical guidelines and standardized methodologies for the noninvasive assessment of gastrointestinal parasites of primates.

Characterization of a Novel Virus Causing a Lethal Disease in Carp and Koi

Since 1998 a lethal disease of carp and ornamental koi (Cyprinus carpio) has afflicted fisheries in North America, Europe, and Asia, causing severe economic losses to the fish farming industry. This review summarizes the isolation and identification of the disease-causing agent and describes the currently known molecular characteristics of this newly isolated virus, distinguishing it from other known large DNA viruses. In addition, we summarize the clinical and histopathological manifestations of the disease. Providing information on the immune response to this virus and evaluating the available means of diagnosis and protection should help to reduce the damage induced by this disease. This review does not discuss the economic aspects of the disease or the debate on whether the disease should be registered; both of these issues were recently reviewed in detail (O. L. M. Haenen, K. Way, S. M. Bergmann, and E. Ariel, Bull. Eur. Assoc. Fish Pathol. 24:293-307, 2004; D. Pokorova, T. Vesely, V. Piackova, S. Reschova, and J. Hulova, Vet. Med. Czech. 50:139-147, 2005).     

Characterization of a Novel Picornavirus Isolate from a Diseased European Eel (Anguilla anguilla)

A novel picornavirus was isolated from specimens of a diseased European eel (Anguilla anguilla). This virus induced a cytopathic effect in eel embryonic kidney cells and high mortality in a controlled transmission study using elvers. Eel picornavirus has a genome of 7,496 nucleotides that encodes a polyprotein of 2,259 amino acids. It has a typical picornavirus genome layout, but its low similarity to known viral proteins suggests a novel species in the family Picornaviridae.     

Hepatitis G virus (GBV-C) infection among Brazilian patients with chronic liver disease and blood donors

Background: The recently discovered hepatitis G virus (HGV) belongs, as hepatitis C virus (HCV), to the Flaviviridae family. HGV has been isolated from the serum of patients with non A-E hepatitis. However, the association of HGV with hepatitis is uncertain.Objective: To determine the HGV prevalence in blood donors and in patients with liver disease and to evaluate a possible correlation between HGV infection and liver disease.Study design: Sera from a total of 113 consecutive patients with chronic liver disease were submitted to a series of liver enzymes and function tests and analyzed for the presence of HBsAg, anti-HBs, anti-HBc, anti-HCV, HCV RNA and HGV RNA. Prevalence of HGV RNA was determined in a group of 87 blood donors.Results: Nine (10%) sera from blood donors and 15 (13%) sera from patients with chronic liver disease were HGV RNA positive. Some 28 (25%) patients were HCV RNA positive, with genotypes 1a, 1b and 3 present in 10, 12 and 5 patients, respectively. A total of 20 (18%) patients were HBsAg carriers. Five (4%) patients were double infected (one with HBV+HCV, one with HBV+HGV and three with HCV+HGV).Conclusion: The proportion (10%) of HGV-infected blood donors was very high when compared with other countries. The results did not allow to establish HGV as an etiologic agent for chronic liver disease. The parenteral route was the presumed means of HGV transmission for only one-third of the patients.     

Different Gene Networks Are Disturbed by Zika Virus Infection in A Mouse Microcephaly Model

The association of Zika virus (ZIKV) infection with microcephaly has raised alarm worldwide. Their causal link has been confirmed in different animal models infected by ZIKV. However, the molecular mechanisms underlying ZIKV pathogenesis are far from clear. Hence, we performed global gene expression analysis of ZIKV-infected mouse brains to unveil the biological and molecular networks underpinning microcephaly. We found significant dysregulation of the sub-networks associated with brain development, immune response, cell death, microglial cell activation, and autophagy amongst others. We provided detailed analysis of the related complicated gene networks and the links between them. Additionally, we analyzed the signaling pathways that were likely to be involved. This report provides systemic insights into not only the pathogenesis, but also a path to the development of prophylactic and therapeutic strategies against ZIKV infection.     

Molecular epidemiology of enteroviruses with special reference to their potential role in the etiology of insulin-dependent diabetes mellitus (IDDM). A review

Background: Several lines of evidence suggest that enterovirus infections may be involved in the etiology of the insulin-dependent diabetes mellitus (IDDM). Often in the literature, a reference is given to specifically diabetogenic strains of enterovirus but there is no systematic assessment about the generation of such strains in the course of evolution or about their abundance among the 64 enterovirus serotypes pathogenic to man. If enteroviruses truly are involved in the etiology of IDDM, a possibility to prevent the disease with enterovirus vaccines might become feasible. In such a situation it would be important to know which serotypes and strains are the most important ones, and whether there would be differences between the strains as regards the pathogenetic mechanisms involved.Objective: To present a brief summary of the basic biology of enteroviruses, on existing data of genetic variation of enteroviruses, and on molecular epidemiology of human enteroviruses with special reference to the different epidemiological modes of their putative involvement in the pathogenesis of IDDM.Conclusions: Like RNA viruses in general, enteroviruses exist as a quasispecies, a mixture of genetic microvariants with a vast potential to adapt to new environments. This means that specifically beta cell-tropic and potentially diabetogenic variants could, in theory, emerge sporadically during systemic infection of any individual. The patterns of genetic diversification of enteroviruses, cocirculation of separate genetic lineages in the human populations, and the assumed geographical restrictions of endemic transmission of the lineages, allow one to hypothesize that populations with a high persisting IDDM incidence might be endemically infected by some specific strains of enteroviruses. However, so far, there is no systematically collected data supporting this hypothesis.     

Sublethal effects of iridovirus disease in a mosquito

Recognition of the importance of debilitating effects of insect virus diseases is currently growing. Commonly observed effects of sublethal infection at the individual level include extended development times, reduced pupal and adult weights, and lowered fecundity. However, for the most part, sublethal infections are assumed to be present in survivors of an inoculum challenge, rather than demonstrated to be present by microscopy or molecular techniques. Invertebrate iridescent viruses are dsDNA viruses capable of causing disease with symptoms obvious to the naked eye, a “patent” infection, that is lethal. Furthermore, inapparent “covert” infections may occur that are non-lethal and which can only be detected using bioassay or molecular techniques. In this study, replication of Invertebrate iridescent virus 6 in Aedes aegypti larvae was demonstrated in the absence of patent disease. A sensitive insect bioassay (using Galleria mellonella) allowed the detection of covert infections, which were more common than patent infections. A concentration-response relationship was detected for the incidence of patent infections. Covert infections were up to 2 orders of magnitude commoner than patent infections, but the prevalence of covert infections did not appear to be related to virus inoculum concentration. Exposure of larvae to virus inoculum resulted in extended juvenile development times. A reduction in the mean and an increase in the variability of fecundity and adult progeny production was observed in females exposed to an inoculum challenge, although formal analysis was not possible. Males appeared capable of passing virus to uninfected females during the mating process. Covertly infected females were smaller and had shorter lifespans than control or virus-challenged females. A conservative estimate for the reduction in the net reproductive rate (R ₀) of such insects was calculated at slightly more than 20% relative to controls. Received: 5 October 1998 / Accepted: 13 February 1999     

Prevalence of infection with HIV,hepatitis B and C viruses,in four high risk groups in Eritrea

Background: Little is known about the prevalence of infections in different population groups in Africa, and about the influence of living conditions on the spread of infections. This study is the first of its kind in the state of Eritrea and is expected to serve as an evaluation of the situation in the country.Objective: A serosurvey for human immunodeficiency virus (HIV), hepatitis B virus (HBV) and hepatitis C virus (HCV) was carried out during the summer of 1995 in Massawa, a small sea port in Eritrea (East Africa) in four groups considered to be at risk for these infections.Study design: The study subjects were former Guerrilla Fighters, Female Sex Workers, Truck Drivers, and Port Workers. Participants from a tribe called Rashaida were believed to be at low risk, and thus served as a control.Results: The Female Sex Workers had the highest incidence of HIV-1 infection, 29%, compared to 10% for Port Workers, and 3% for Guerrilla Fighters. On the other hand presence of HBsAg, indicating a high prevalence of hepatitis B carrier status, was highest in the Guerrilla Fighters, followed by the Rashaidas, and lowest in the Female Sex Workers. The Female Sex Workers were further tested for antibodies against HBV and the results revealed that 53% of them, 5%, had antibodies against HBcoreAg. Excluding the possibility of an acute infection at sampling time, three of them became HBsAg carriers. Surprisingly, our group of Truck Drivers did not show HIV-1 infection, and no HIV-2 infections were seen in the whole cohort.Conclusion: The study shows that the described groups have different prevalences of infection with HIV, hepatitis B and C which can partly be explained by their living conditions.     

Development of an enterovirus specific PCR method for the quantification of enterovirus genomes in blood of diabetes patients

Background: Insulin-dependent diabetes mellitus or type 1 diabetes is a disease with a diverse aetiology. Epidemiological studies examining newly diagnosed, recent onset IDDM patients have suggested a role for viruses in the aetiology of IDDM (Yoon, 1995, Diabetes/Metabolism Reviews 11, 83–107). Important candidates are the enteroviruses, in particular coxsackieviruses B3 and B4. The latter can cause diabetes in animals (Clements et al., 1995, Lancet 346, 221–223).Objectives: We have developed a quantitative PCR method for the detection of enterovirus genomes in biological samples. The quantitative PCR will be used to screen for enteroviruses in blood of diabetes patients and their relatives by testing a Blood Diabetes Register.Study design: A substantial amount of data has been collected on enterovirus induced IDDM, our study is original in so far as it will be: (1) a quantitative study, not only the presence of viral genome sequences in blood will be determined, but also their concentrations (viral load); and (2) a longitudinal study, samples are and will be collected as a function of time. Positive PCR samples will be quantified using the standard addition method.Results: The test is specific for enteroviruses, since all enteroviruses were detected with equal sensitivity. Viruses belonging to other picornavirus genera scored negative (even up to 3×10⁶ genome copies). An equal detection limit of 10 genome copies was found for all enteroviruses.Conclusions: The developed method will permit us to generate quantitative and longitudinal data of enterovirus genomes in blood of diabetes patients and their relatives, which might help in the elucidation of the relationship between enteroviruses and IDDM.     

Assessment of the specificity of a commercial human parvovirus B19 IgM assay

Background: It is important to investigate a possible cross-reaction of anti-rubella IgM in the IDEIA^™ Parvovirus B19 IgM test because many B19 infections are either asymptomatic or have clinical symptoms similar to those of rubella virus infections. Epstein-Barr virus (EBV) IgM, cytomegalovirus (CMV) IgM, measles IgM and rheumatoid factor (RF) IgM cross-reactions were also studied.Objectives: In the period from February to September 1994 (including a parvovirus B19 epidemic) more than 10 000 serum samples were examined for parvovirus B19 IgM in Denmark. This gave an opportunity to evaluate the commercial IDEIA^™ Parvovirus B19 ELISA kit (DAKO A/S, Glostrup, Denmark), which was used routinely at Statens Serum Institut from the beginning of 1994 and onwards.Study design: A total of 123 parvovirus B19 IgM positive sera were tested for reactivity in rubella IgM EIA. A total of 78 rubella IgM positive sera, 60 EBV VCA-IgM positive sera, 30 CMV IgM positive sera and 24 measles virus IgM positive sera were tested for reaction in IDEIA^™ Parvovirus B19 IgM test. Finally, 25 parvovirus IgM positive sera were tested for specific IgM against measles virus, EBV (VCA), CMV and for RF.Results: One anti-B19 IgM positive serum sample reacted positively in the rubella IgM test. Of rubella IgM positive serum samples 4% cross-reacted in IDEIA^™ Parvovirus B19 IgM test, as did 17 and 20% of EBV VCA-IgM and CMV IgM positive serum samples respectively. None of measles virus IgM positive serum samples cross-reacted in the IDEIA^™ Parvovirus B19 IgM test. Of 25 initially parvovirus B19 IgM positive sera 20% cross-reacted in EBV VCA IgM test and 8% in the CMV IgM test. None reacted positively in measles virus IgM test; 28% showed weak reactivity in RF IgM test.Conclusions: Precautions must be taken when results of IgM assays are interpreted. Epidemiological and clinical observations must be considered.     

Slender,Older Women Appear to Be More Susceptible to Nontuberculous Mycobacterial Lung Disease

Background: Nontuberculous mycobacteria (NTM) are environmental microbes that are associated with a variety of human diseases, particularly chronic lung infections. Over the past several decades, NTM lung disease has been increasingly seen in postmenopausal women with slender body habitus.Objective: This article reviewed the clinical and experimental evidence that supports the observation that thin older women (aged 50–80 years) are predisposed to NTM lung disease. We posited 3 potential pathways for this predisposition: relative estrogen deficiency, abnormal levels of adipokines that alter immune responses, and abnormal expression of transforming growth factor-β (TGF-β) related to fibrillin anomalies similar to Marfan syndrome (MFS).Methods: Using the PubMed database, a literature search was performed (all publications up to July 2009) by pairing the key phrase nontuberculous mycobacteria with weight, malnutrition, female gender, body habitus, leptin, adipokines, estrogen, menopause, postmenopausal, or body mass index. Non-English-language articles were included if their abstracts were in English. Relevant articles were also identified from the abstracts.Results: Published case reports and series indicate that in the past 20 years, NTM lung disease has been recognized in disproportionately increased numbers in postmenopausal women. Among these patients, slender body habitus and thoracic cage abnormalities, such as pectus excavatum and scoliosis, are commonly described. Notably, no long-term prospective clinical studies exist to corroborate that low weight is an independent risk factor for NTM lung disease. However, based on the findings of a limited number of experimental studies, we hypothesize that decreased leptin, increased adiponectin, and/or decreased estrogen in older women with slender body habitus may account for their increased susceptibility to NTM infections. We further speculate that in some patients with features mindful of MPS (slender, scoliosis, pectus excavatum, or mitral valve prolapse), there may be anomalies of fibrillin, similar to MFS, that lead to the expression of the immunosuppressive cytokine TGP-β further increasing their susceptibility to NTM.Conclusions: It is likely that both sufficient environmental exposure and host susceptibility are required for the establishment of NTM lung disease. The observation that NTM lung infections are more common in slender, older women without any overt immune defects suggests that abnormal expression of adipokines, sex hormones, and/or TGF-β may play an important role in their susceptibility.     

Need for research on estrogen receptor function: Importance for postmenopausal hormone therapy and atherosclerosis

Background: Cardiovascular disease is the leading cause of morbidity and mortality in men and women worldwide. Although rare in premenopausal women, its incidence rises sharply after menopause, indicating atheroprotective effects of endogenous estrogens.Objective: This review discusses the differential effects of estrogen receptor function on atherosclerosis progression in pre- and postmenopausal women, including aspects of gender differences in vascular physiology of estrogens and androgens.Methods: Recent advances in the understanding of the pathogenesis of atherosclerosis, estrogen receptor function, and hormone therapy are reviewed, with particular emphasis on clinical and molecular issues.Results: Whether hormone therapy can improve cardiovascular health in postmenopausal women remains controversial. Current evidence suggests that the vascular effects of estrogen are affected by the stage of reproductive life, the time since menopause, and the extent of subclinical atherosclerosis. The mechanisms of vascular responsiveness to sex steroids during different stages of atherosclerosis development remain poorly understood in women and men.Conclusion: In view of the expected increase in the prevalence of atherosclerotic vascular disease worldwide due to population aging, research is needed to determine the vascular mechanism of endogenous and exogenous sex steroids in patients with atherosclerosis. Such research may help to define new strategies to improve cardiovascular health in women and possibly also in men.     

An approach to understanding the mechanisms of poliovirus persistence in infected cells of neural or non-neural origin

Background: Poliovirus (PV) is the etiologic agent of paralytic poliomyelitis, which is sometimes followed, after decades of clinical stability, by new symptoms, including progressive muscular atrophy, collectively known as the post-polio syndrome. This raises the question of possible PV persistence in post-polio patients.Objective: To test the capacity of PV to establish persistent infections in human cells, three models were developed.Study design: This review focuses on the viral and cellular parameters involved in persistent PV infection.Results: Many PV strains, which are generally lytic in primate cell lines, are able to establish persistent infections in human neuroblastoma cells. During persistent infection, PV mutants (PVpi) are consistently selected, and several of their capsid substitutions occur at positions known to be involved in PV–PV receptor interactions. PVpi have a particular property: they can establish persistent infections in non-neural HEp-2 cells. PV can also persistently infect primary cultures of human fetal brain cells and the majority of cells which survive infection belong to the neuronal lineage.Conclusions: The results obtained with the three models of persistent PV infection in human cells suggest that several mechanisms are used by PV to establish and maintain persistent infections in neural and non-neural cells. The interactions of the virus with its receptor seem to be a key-step in all cases. In the future, the elucidation of the etiology of the post-polio syndrome will require the characterization of PV sequences having persisted for decades in post-polio patients.     

Evolution of Picornaviridae: An examination of phylogenetic relationships and cophylogeny

Picornaviruses are responsible for some of the most common and debilitating illnesses affecting humans and animals worldwide. To extend our knowledge of the evolution of picornaviruses and their molecular epidemiology, phylogenetic relationships among 11 genera and the unassigned seal picornavirus type 1 were estimated from the conserved proteins 2C, 3C^pro, and 3D^pol. Each gene was analyzed separately and as a combined dataset. Different tree topologies were recovered from each gene. However, their sequences were determined to be combinable based on our finding of no recombination among genera and failing to reject the hypothesis of homogeneity among datasets using ILD tests. The combined data tree topology was identical to the 3D^pol gene tree; a topology largely consistent with previous phylogenetic hypotheses based on 3D^pol and the coding genome. Phylogenetic trees estimated from six phenotypic characters were not congruent with those recovered from molecular datasets; further supporting the hypothesis that viral phenotypes are highly plastic. Finally, we tested the hypothesis of host–virus cophylogeny. Both global and individual tests of the relationships between host and virus trees failed to detect a significant association. These results emphasize the importance of horizontal transmission among host species for picornavirus diversification rather than vertical transmission accompanying speciation.     

TSH Receptor Antibodies: Relevance & Utility

Objective: Antibodies (Abs) to the thyrotropin (TSH) receptor (TSH-R) play an important role in the pathogenesis of autoimmune thyroid disease (AITD). We define the complex terminology that has arisen to describe TSH-R-Abs, review the mechanisms of action of the various types of TSH-R-Abs, and discuss significant advances that have been made in the development of clinically useful TSH-RAb assays.Methods: Literature review and discussion.Results: TSH-R-Abs may mimic or block the action of TSH or be functionally neutral. Stimulating TSH-R-Abs are specific biomarkers for Graves disease (GD) and responsible for many of its clinical manifestations. TSH-R-Abs may also be found in patients with Hashimoto thyroiditis in whom they may contribute to the hypothyroidism of the disease. Measurement of TSH-R-Abs in general, and functional Abs in particular, is recommended for the rapid diagnosis of GD, differential diagnosis and management of patients with AITD, especially during pregnancy, and in AITD patients with extrathyroidal manifestations such as orbitopathy. Measurement of TSH-R-Abs can be done with either immunoassays that detect specific binding of Abs to the TSH-R or cell-based bioassays that also provide information on their functional activity and potency. Application of molecular cloning techniques has led to significant advances in methodology that have enabled the development of clinically useful bioassays. When ordering TSH-R-Ab, clinicians should be aware of the different tests available and how to interpret results based on which assay is performed. The availability of an international standard and continued improvement in bioassays will help promote their routine performance by clinical laboratories and provide the most clinically useful TSH-R-Ab results.Conclusion: Measurement of TSH-R-Abs in general, and functional (especially stimulating) Abs in particular, is recommended for the rapid diagnosis, differential diagnosis, and management of patients with Graves hyperthyroidism, related thyroid eye disease, during pregnancy, as well as in Hashimoto thyroiditis patients with extra-thyroidal manifestations and/or thyroid-binding inhibiting immunoglobulin positivity.Abbreviations: Ab = antibody; AITD = autoimmune thyroid disease; ATD = antithyroid drug; cAMP = cyclic adenosine 3′,5′-monophosphate; ELISA = enzyme-linked immunosorbent assay; GD = Graves disease; GO = Graves orbitopathy; HT = Hashimoto thyroiditis; MAb = monoclonal antibody; TBAb = thyrotropin receptor blocking antibody; TBII = thyroid-binding inhibiting immunoglobulin; TSAb = thyrotropin receptor–stimulating antibody; TSB-Ab or TRBAb = thyrotropin receptor–stimulating blocking antibody; TSH = thyrotropin; TSH-R = thyrotropin receptor     

Development and Application of a Blastocystis Subtype-Specific PCR Assay Reveals that Mixed-Subtype Infections Are Common in a Healthy Human Population

The human gut is host to a diversity of microorganisms, including the single-celled microbial eukaryote Blastocystis. Research has shown that most carriers host a single Blastocystis subtype (ST), which is unusual given the considerable within-host species diversity observed for other microbial genera in this ecosystem. However, our limited knowledge of both the incidence and biological significance of Blastocystis diversity within hosts (i.e., so-called mixed infections) is likely due to problems with existing methodologies. Here, we developed and applied Blastocystis ST-specific PCRs for the investigation of the most common subtypes of Blastocystis (ST1 to ST4) to a healthy human cohort (n = 50). We detected mixed infections in 22% of the cases, all of which had been identified as single-ST infections in a previous study using state-of-the-art methods. Our results show that certain STs occur predominantly as either single (ST3 and 4) or mixed (ST1) infections, which may reflect inter alia transient colonization patterns and/or cooperative or competitive interactions between different STs. Comparative analyses with other primers that have been used extensively for ST-specific analysis found them unsuitable for detection of mixed- and, in some cases, single-ST infections. Collectively, our data shed new light on the diversity of Blastocystis within and between human hosts. Moreover, the development of these PCR assays will facilitate future work on the molecular epidemiology and significance of mixed infections in groups of interest, including health and disease cohorts, and also help identify sources of Blastocystis transmission to humans, including identifying potential animal and environmental reservoirs.     

Virus-like particles in picornavirus vaccine development

Virus-like particles (VLP), which are similar to natural virus particles but do not contain viral genes, have brought about significant breakthroughs in many research fields because of their unique advantages. The ordered repeating epitopes of VLP can induce immunity responses similar to those prompted by natural viral infection; thus, VLP vaccines are regarded as candidate alternatives to whole-virus vaccines. As picornavirus has serious impacts on human and animal health, the development of efficient and safe vaccines is a key endeavor in preventing virus infections. The characteristics of picornavirus capsid proteins allow the development of VLP vaccines. This paper investigates research scenarios and progress on picornavirus VLP vaccines with the aim of providing a reference for researchers focusing on virology and vaccinology.