Strain-specific requirements of susceptibility to rhesus enteric calicivirus infection

Recently, we identified the coxsackie and adenovirus receptor (CAR) as the entry receptor for rhesus enteric calicivirus (ReCV) isolate FT285 and demonstrated that co-expression of the CAR and the type B histo-blood group antigen (HBGA) is required to convert the resistant CHO cell line susceptible to infection. To address whether the CAR is also the functional entry receptor for other ReCV isolates and the requirement for specific HBGAs or other glycans, here we used a panel of recombinant CHO cell lines expressing the CAR and the type A, B, or H HBGAs alone or in combination. Infection studies with three diverse ReCV strains, the prototype GI.1 Tulane virus (TV), GI.2 ReCV-FT285, and GI.3 ReCV-FT7, identified that cell surface expression of the CAR is an absolute requirement for all three strains to promote susceptibility to infection, while the requirement for HBGAs varies among the strains. In addition to the CAR, ReCV-FT285 and TV require type A or B HBGAs for infection. In the absence of HBGAs, TV, but not Re-CV FT285, can also utilize sialic acids, while ReCV-FT7 infection is HBGA-independent and relies on CAR and sialic acid expression. In summary, we demonstrated strain-specific diversity of susceptibility requirements for ReCV infections and that CAR, type A and B HBGA, and sialic acid expression control susceptibility to infection with the three ReCV isolates studied. Our study also indicates that the correlation between in vitro HBGA binding and HBGAs required for infection is relatively high, but not absolute. This has direct implications for human noroviruses.IMPORTANCEHuman noroviruses (HuNoVs) are important enteric pathogens. The lack of a robust HuNoV cell culture system is a bottleneck for HuNoV cell culture-based studies. Often, cell culture-adapted caliciviruses that rapidly replicate in conventional cell lines and recapitulate biological features of HuNoVs are utilized as surrogates. Particularly, rhesus enteric caliciviruses (ReCVs) display remarkable similarities, including the primate host, clinical manifestation of gastroenteritis, genetic/antigenic diversity, and reliance on histo-blood group antigens (HBGAs) for attachment. While the HuNoV entry receptor(s) is unknown, the coxsackie and adenovirus receptor (CAR) has recently been identified as the ReCV entry receptor. Here, we identified the CAR, the type A and B HBGAs, and sialic acids as critical cell surface molecules controlling susceptibility to ReCV infections. The CAR is required for all ReCV isolates studied. However, the requirement for the different carbohydrate molecules varies among different ReCV strains. Our findings have direct implications for HuNoVs.

Tachycardia dependent early repolarisation pattern in subarachnoid haemorrhage related takotsubo syndrome

We present a case of a patient who suffered subarachnoid haemorrhage (SAH), complicated by takotsubo syndrome, paroxysmal atrial fibrillation and ECG repolarisation abnormality, compatible with Brugada phenocopy. The early repolarisation morphology showed a paradox association with the cardiac cycle length; a relationship not yet documented in SAH. Our observation also sheds light on the genesis of the "spiked helmet" ECG sign.

Effects of Handshake Duration on Other Nonverbal Behavior

Although detailed descriptions of proper handshakes partly comprise many etiquette books, how a normal handshake can be described, its proper duration, and the consequences of violating handshake expectations remain empirically unexplored. This study measured the effect of temporal violations of the expected length of a handshake (less than three seconds according to previous studies) administered unobtrusively in a naturalistic experiment. We compared volunteer participants' (N = 34; 25 females; 9 males; M_age = 23.76 years, SD = 6.85) nonverbal behavior before and after (a) a prolonged handshake (>3 seconds), (b) a normal length handshake (average length <3 seconds), and (c) a control encounter with no handshake. Frame-by-frame behavioral analyses revealed that, following a prolonged handshake (vs. a normal length or no handshake), participants showed less interactional enjoyment, as indicated by less laughing. They also showed evidence of anxiety and behavioral freezing, indicated by increased hands-on-hands movements, and they showed fewer hands-on-body movements. Normal length handshakes resulted in less subsequent smiling than did prolonged handshakes, but normal length handshakes were also followed by fewer hands-on-face movements than prolonged handshakes. No behavior changes were associated with the no-handshake control condition. We found no differences in participants' level of empathy or state/trait anxiety related to these conditions. In summary, participants reacted behaviorally to temporal manipulations of handshakes, with relevant implications for interactions in interviews, business, educational, and social settings and for assisting patients with social skills difficulties.

Recovirus NS1-2 Has Viroporin Activity That Induces Aberrant Cellular Calcium Signaling To Facilitate Virus Replication

Enteric viruses in the Caliciviridae family cause acute gastroenteritis in humans and animals, but the cellular processes needed for virus replication and disease remain unknown. A common strategy among enteric viruses, including rotaviruses and enteroviruses, is to encode a viral ion channel (i.e., viroporin) that is targeted to the endoplasmic reticulum (ER) and disrupts host calcium (Ca2+) homeostasis. Previous reports have demonstrated genetic and functional similarities between the nonstructural proteins of caliciviruses and enteroviruses, including the calicivirus NS1-2 protein and the 2B viroporin of enteroviruses. However, it is unknown whether caliciviruses alter Ca2+ homeostasis for virus replication or whether the NS1-2 protein has viroporin activity like its enterovirus counterpart. To address these questions, we used Tulane virus (TV), a rhesus enteric calicivirus, to examine Ca2+ signaling during infection and determine whether NS1-2 has viroporin activity that disrupts Ca2+ homeostasis. We found that TV increases Ca2+ signaling during infection and that increased cytoplasmic Ca2+ levels are important for efficient replication. Further, TV NS1-2 localizes to the endoplasmic reticulum, the predominant intracellular Ca2+ store, and the NS2 region has characteristics of a viroporin domain (VPD). NS1-2 had viroporin activity in a classic bacterial functional assay and caused aberrant Ca2+ signaling when expressed in mammalian cells, but truncation of the VPD abrogated these activities. Together, our data provide new mechanistic insights into the function of the NS2 region of NS1-2 and support the premise that enteric viruses, including those within Caliciviridae, exploit host Ca2+ signaling to facilitate their replication.IMPORTANCE Tulane virus is one of many enteric caliciviruses that cause acute gastroenteritis and diarrheal disease. Globally, enteric caliciviruses affect both humans and animals and amass >65 billion dollars per year in treatment and health care-associated costs, thus imposing an enormous economic burden. Recent progress has resulted in several cultivation systems (B cells, enteroids, and zebrafish larvae) to study human noroviruses, but mechanistic insights into the viral factors and host pathways important for enteric calicivirus replication and infection are still largely lacking. Here, we used Tulane virus, a calicivirus that is biologically similar to human noroviruses and can be cultivated by conventional cell culture, to identify and functionally validate NS1-2 as an enteric calicivirus viroporin. Viroporin-mediated calcium signaling may be a broadly utilized pathway for enteric virus replication, and its existence within caliciviruses provides a novel approach to developing antivirals and comprehensive therapeutics for enteric calicivirus diarrheal disease outbreaks.

Natural Norovirus Infections in Rhesus Macaques

Using a recently developed real-time reverse transcription PCR, I retested 500 fecal samples from rhesus macaques collected in 2008. Previous conventional reverse transcription PCR testing identified 1 isolate of GII norovirus; retesting found GI, GII, and possible GIV noroviruses in the samples, indicating the natural circulation of noroviruses in nonhuman primate colonies.

Renilla Luciferase-LC3 Based Reporter Assay for Measuring Autophagic Flux

Macroautophagy (autophagy) is a dynamic intracellular degradation pathway. Monitoring the flux through the autophagy pathway is experimentally challenging but obviously a prerequisite for the proper investigation of the process. Here, we present an indirect autophagy flux assay based on monitoring the degradation of an autophagosome-associated fusion protein Rluc-LC3 by luminescence detection. The method is suitable for screening purposes with a high number of parallel samples and can be used for measurements in cell lysates as well as in living cells. The Rluc-LC3 assay has proven useful for the identification of genes, miRNAs, and small molecules that regulate autophagy flux in mammalian cells.

Multiplex real-time RT-PCR for the simultaneous detection and quantification of GI, GII and GIV noroviruses

Noroviruses are important causes of acute gastroenteritis and are classified into six genogroups with GI, GII and GIV containing human pathogens. This high genetic diversity represents a significant challenge for diagnostic assay development. Genogroup specific monoplex and multiplex real time RT-PCR assays are widely used for the detection of GI and GII noroviruses. On the other hand, GIV norovirus detection is not part of routine laboratory diagnosis. This study describes the development and evaluation of a one tube, real time RT-PCR assay for the simultaneous detection and quantification of GI, GII and GIV noroviruses, including both GIV.1 (human) and GIV.2 (animal) strains. Assay performance was evaluated on a panel of norovirus positive clinical samples by comparison of monoplex and multiplex standard curves and Ct values. The multiplex assay demonstrated equal sensitivity and specificity to the monoplex assays and was able to detect all GI, GII and GIV noroviruses with Ct values equal to that of the monoplex assays. The multiplex assay described in this study will be instrumental for the better understanding of GIV norovirus epidemiology, including their possible zoonotic nature.

Tulane Virus as a Potential Surrogate To Mimic Norovirus Behavior in Oysters

Oyster contamination by noroviruses is an important health and economic problem. The present study aimed to compare the behaviors of Norwalk virus (the prototype genogroup I norovirus) and two culturable viruses: Tulane virus and mengovirus. After bioaccumulation, tissue distributions were quite similar for Norwalk virus and Tulane virus, with the majority of viral particles detected in digestive tissues, while mengovirus was detected in large amounts in the gills and mantle as well as in digestive tissues. The levels of persistence of all three viruses over 8 days were comparable, but clear differences were observed over longer periods, with Norwalk and Tulane viruses displaying rather similar half-lives, unlike mengovirus, which was cleared more rapidly. These results indicate that Tulane virus may be a good surrogate for studying norovirus behavior in oysters, and they confirm the prolonged persistence of Norwalk virus in oyster tissues.

Feline Calicivirus, Murine Norovirus, Porcine Sapovirus, and Tulane Virus Survival on Postharvest Lettuce

Human norovirus (HuNoV) is the leading cause of foodborne illnesses, with an increasing number of outbreaks associated with leafy greens. Because HuNoV cannot be routinely cultured, culturable feline calicivirus (FCV), murine norovirus (MNV), porcine sapovirus (SaV), and Tulane virus (TV) have been used as surrogates. These viruses are generated in different cell lines as infected cell lysates, which may differentially affect their stability. Our objective was to uniformly compare the survival of these viruses on postharvest lettuce while evaluating the effects of cell lysates on their survival. Viruses were semipurified from cell lysates by ultrafiltration or ultracentrifugation followed by resuspension in sterile water. Virus survival was examined before and after semipurification: in suspension at room temperature (RT) until day 28 and on lettuce leaves stored at RT for 3 days or at 4°C for 7 and 14 days. In suspension, both methods significantly enhanced the survival of all viruses. On lettuce, the survival of MNV in cell lysates was similar to that in water, under all storage conditions. In contrast, the survival of FCV, SaV, and TV was differentially enhanced, under different storage conditions, by removing cell lysates. Following semipurification, viruses showed similar persistence to each other on lettuce stored under all conditions, with the exception of ultracentrifugation-purified FCV, which showed a higher inactivation rate than MNV at 4°C for 14 days. In conclusion, the presence of cell lysates in viral suspensions underestimated the survivability of these surrogate viruses, while viral semipurification revealed similar survivabilities on postharvest lettuce leaves.

The master regulator of IncA/C plasmids is recognized by the Salmonella Genomic island SGI1 as a signal for excision and conjugal transfer

The genomic island SGI1 and its variants, the important vehicles of multi-resistance in Salmonella strains, are integrative elements mobilized exclusively by the conjugative IncA/C plasmids. Integration and excision of the island are carried out by the SGI1-encoded site-specific recombinase Int and the recombination directionality factor Xis. Chromosomal integration ensures the stable maintenance and vertical transmission of SGI1, while excision is the initial step of horizontal transfer, followed by conjugation and integration into the recipient. We report here that SGI1 not only exploits the conjugal apparatus of the IncA/C plasmids but also utilizes the regulatory mechanisms of the conjugation system for the exact timing and activation of excision to ensure efficient horizontal transfer. This study demonstrates that the FlhDC-family activator AcaCD, which regulates the conjugation machinery of the IncA/C plasmids, serves as a signal of helper entry through binding to SGI1 xis promoter and activating SGI1 excision. Promoters of int and xis genes have been identified and the binding site of the activator has been located by footprinting and deletion analyses. We prove that expression of xis is activator-dependent while int is constitutively expressed, and this regulatory mechanism is presumably responsible for the efficient transfer and stable maintenance of SGI1.

Noninvasive continuous arterial pressure measurements in the assessment of acute, severe central hypovolemia

Acute, severe hypovolemia is a medical emergency. Traditional vital sign parameters allow no optimal triage. High predictive power of finger plethysmography-based stroke volume (SV) and pulse pressure (PP) was recently suggested. To assess the performance of the PP and SV parameters, lower body negative pressure of -40 mmHg, than -60 mmHg - corresponding to moderate and severe central hypovolemia - was applied in 22 healthy males (age 35 ± 7 years). Slow breathing induced fluctuations in the above indices, characterized by stroke volume variability (SVV), and pulse pressure variability (PPV), were assessed. Responses in heart rate (HR) and shock index (SI) were also studied. Discriminative capacity of these parameters was characterized by the area under the ROC (receiver operating characteristic) curves (AUC).

RESULTS

In comparison of baseline to severe central hypovolemia SV, PP, HR, and SI showed good discriminating capacity (AUC 99%, 88%, 87%, and 93%, respectively). The discriminating capacity of SVV and PPV was poor (77% and 70%, respectively). In comparison of moderate and severe hypovolemia, the discriminating capacity of the studied parameters was uniformly limited.

CONCLUSIONS

Plethysmography-based SV and PP parameters can be used to detect acute severe volume loss. Sensitive parameters discriminating moderate and severe central hypovolemia are still lacking.

Rhesus enteric calicivirus surrogate model for human norovirus gastroenteritis

Human noroviruses are one of the major causes of acute gastroenteritis worldwide. Due to the lack of an efficient human norovirus cell culture system coupled with an animal model, human norovirus research mainly relies on human volunteer studies and surrogate models. Current models either utilize human norovirus-infected animals including the gnotobiotic pig or calf and the chimpanzee models, or employ other members of the family Caliciviridae including cell culture propagable surrogate caliciviruses such as the feline calicivirus, murine norovirus and most recently the Tulane virus. One of the major features of human noroviruses is their extreme biological diversity, including genetic, antigenic and histo-blood group antigen binding diversity, and possible differences of virulence and environmental stability. This extreme biological diversity and its effect on intervention/prevention strategies cannot be modelled by uniform groups of surrogates, much less by single isolates. Tulane virus, the prototype recovirus strain, was discovered in 2008. Since then, several other novel recoviruses have been described and cell culture adapted. Recent studies indicate that the epidemiology, the biological features and diversity of recoviruses and the course of infection and clinical disease in recovirus-infected macaques more closely reflect those properties of human noroviruses than any of the current surrogates. This review aims to summarize what is currently known about recoviruses, highlight their biological similarities to human noroviruses and discuss applications of the model in addressing questions relevant for human norovirus research.

Acetyl-L-carnitine and oxaloacetate in post-treatment against LTP impairment in a rat ischemia model. An in vitro electrophysiological study

A high proportion of research relating to cerebral ischemia focuses on neuroprotection. The application of compounds normally present in the organism is popular, because they do not greatly influence the synaptic activity by receptor modulation, and can be administered without serious side effects. Oxaloacetate (OxAc) and acetyl-L-carnitine (ALC) are such favorable endogenous molecules. ALC can exert a protective effect by improving the energy state of the neurons under ischemic conditions. A promising neuroprotective strategy is glutamate scavenging, which can be achieved by the intravenous administration of OxAc. This study involved the possible protective effects of ALC and OxAc in different post-treatment protocols against long-term potentiation (LTP) impairment. Ischemia was induced in rats by 2-vessel occlusion, which led to a decreased LTP relative to the control group. High-dose (200 mg/kg) ALC or OxAc post-treatment resulted in a higher potentiation relative to the 2VO group, but it did not reach the control level, whereas low-dose ALC (100 mg/kg) in combination with OxAc completely restored the LTP function. Many previous studies have concluded that ALC can be protective only as pretreatment. The strategy described here reveals that ALC can also be neuroprotective when utilized as post-treatment against ischemia.

Analysis of the ORF2 of human astroviruses reveals lineage diversification, recombination and rearrangement and provides the basis for a novel sub-classification system

Canonical human astroviruses (HAstVs) are important enteric pathogens that can be classified genetically and antigenically into eight types. Sequence analysis of small diagnostic regions at either the 5' or 3' end of ORF2 (capsid precursor) is a good proxy for prediction of HAstV types and for distinction of intratypic genetic lineages (subtypes), although lineage diversification/classification has not been investigated systematically. Upon sequence and phylogenetic analysis of the full-length ORF2 of 86 HAstV strains selected from the databases, a detailed classification of HAstVs into lineages was established. Three main lineages could be defined in HAstV-1, four in HAstV-2, two in HAstV-3, three in HAstV-4, three in HAstV-5 and two in HAstV-6. Intratypic (inter-lineages) ORF2 recombinant strains were identified in type 1 (1b/1d) and type 2 (2c/2b) with distinct crossover points. Other potential intratypic recombinant strains were identified in type 3, type 5 and type 6. In addition, a type-1b strain with a large insertion (~600 bp) of heterologous RNA in the N-terminal region and a type-6 strain with a large RNA rearrangement in the hypervariable region were identified. The classification scheme was integrated in a novel nomenclature system suitable for designation of HAstV strains.

Relationship between genotypes and serotypes of genogroup 1 recoviruses: a model for human norovirus antigenic diversity

Human norovirus (NoV) research greatly relies on cell culture-propagable surrogate caliciviruses, including murine NoVs and the prototype 'recovirus' (ReCV), Tulane virus. However, the extreme biological diversity of human NoVs cannot be modelled by a uniform group of viruses or single isolate. Based on a diverse group of recently described ReCVs, a more advanced model reflecting human NoV biological diversity is currently under development. Here, we have reported the genotypic and serotypic relationships among 10 G1 ReCV isolates, including Tulane virus and nine other recent cell culture-adapted strains. Based on the amino acid sequences of virus capsid protein, VP1, and classification constraints established for NoVs, G1 ReCVs were separated into three genotypes, with variable organization of the three open reading frames. Interestingly, cross-neutralization plaque assays revealed the existence of four distinct serotypes, two of which were detected among the G1.2 strains. The amino acid (aa) difference between the two G1.2 ReCV serotypes (12%) was less than the minimum 13% difference established between NoV genotypes. Interestingly, one of the G1.3 ReCVs was equally neutralized by antisera raised against the G1.3 (6% aa difference) and G1.1 (25% aa difference) representative strains. These results imply the existence of a large number of human NoV serotypes, but also shared cross-neutralization epitopes between some strains of different genotypes. In conclusion, the newly developed ReCV surrogate model can be applied to address biologically relevant questions pertaining to enteric CV diversity.

Neuroprotective effect of oxaloacetate in a focal brain ischemic model in the rat

During an ischemic event, the well-regulated glutamate (Glu) homeostasis is disturbed, which gives rise to extremely high levels of this excitatory neurotransmitter in the brain tissues. It was earlier reported that the administration of oxaloacetate (OxAc) as a Glu scavenger reduces the Glu level in the brain by enhancing the brain-to-blood Glu efflux. Here, we studied the neuroprotective effect of OxAc administration in a new focal ischemic model in rats. Occlusion of the middle cerebral artery resulted in immediate reduction of the somatosensory-evoked responses (SERs), and the amplitudes remained at the reduced level throughout the whole ischemic period. On reperfusion, the SERs started to increase, but never reached the control level. OxAc proved to be protective, since the amplitudes started to recover even during the ischemia, and finally fully regained the control level. The findings of the histological measurements were in accordance with the electrophysiological data. After Fluoro Jade C staining, significantly fewer labeled cells were detected in the OxAc-treated group relative to the control. These results provide new evidence of the neuroprotective effect of OxAc against ischemic injury, which strengthens the likelihood of its future applicability as a novel neuroprotective agent for the treatment of ischemic stroke patients.

Acetyl-L-carnitine normalizes the impaired long-term potentiation and spine density in a rat model of global ischemia

As a consequence of an ischemic episode, energy production is disturbed, leading to neuronal cell death. Despite intensive research, the quest for promising neuroprotective drugs has largely failed, not only because of ineffectiveness, but also because of serious side-effects and dosing difficulties. Acetyl-l-carnitine (ALC) is an essential nutrient which plays a key role in energy metabolism by transporting fatty acids into mitochondria for β-oxidation. It is an endogenous compound and can be used at high dose without toxicity in research into ischemia. Its neuroprotective properties have been reported in many studies, but its potential action on long-term potentiation (LTP) and dendritic spine density has not been described to date. The aim of the present study was an evaluation of the possible protective effect of ALC after ischemic insults inflicted on hippocampal synaptic plasticity in a 2-vessel occlusion (2VO) model in rats. For electrophysiological measurements, LTP was tested on hippocampal slices. The Golgi-Cox staining technique was used to determine spine density. 2VO resulted in a decreased, unstable LTP and a significant loss of dendritic spines. ALC administered after 2VO was not protective, but as pretreatment prior to 2VO it restored LTP nearly to the control level. This finding paralleled the histological analysis: ALC pretreatment resulted in the reappearance of dendritic spines on the CA1 pyramidal cells. Our data demonstrate that ALC administration can restore hippocampal function and spine density. ALC probably acts by enhancing the aerobic metabolic pathway, which is inhibited during and following ischemic attacks.

Post-ischemic treatment with L-kynurenine sulfate exacerbates neuronal damage after transient middle cerebral artery occlusion

Since brain ischemia is one of the leading causes of adult disability and death, neuroprotection of the ischemic brain is of particular importance. Acute neuroprotective strategies usually have the aim of suppressing glutamate excitotoxicity and an excessive N-methyl-d-aspartate (NMDA) receptor function. Clinically tolerated antagonists should antagonize an excessive NMDA receptor function without compromising the normal synaptic function. Kynurenic acid (KYNA) an endogenous metabolite of the tryptophan metabolism, may be an attractive neuroprotectant in this regard. The manipulation of brain KYNA levels was earlier found to effectively enhance the histopathological outcome of experimental ischemic/hypoxic states. The present investigation of the neuroprotective capacity of L-kynurenine sulfate (L-KYNs) administered systemically after reperfusion in a novel distal middle cerebral artery occlusion (dMCAO) model of focal ischemia/reperfusion revealed that in contrast with earlier results, treatment with L-KYNs worsened the histopathological outcome of dMCAO. This contradictory result indicates that post-ischemic treatment with L-KYNs may be harmful.

Fundamental interstrain differences in cortical activity between Wistar and Sprague-Dawley rats during global ischemia

Four-vessel occlusion (4VO), a frequently used model of global cerebral ischemia in rats, results in a dysfunction in wide brain areas, including the cerebral cortex and hippocampus. However, there are pronounced differences in response to global ischemia between the laboratory rat strains used in these studies. In the present work, the immediate acute effects of 4VO-induced global ischemia on the spontaneous electrocorticogram (ECoG) signals were analyzed in Wistar and Sprague-Dawley rats. The ECoG was isoelectric during the 10 min of global cerebral ischemia in Wistar rats and the first burst (FB) was seen 10-13 min after the start of reperfusion. In Sprague-Dawley rats, the FB was detected immediately after the start of 4VO or a few seconds later. The burst suppression ratio (BSR) in Wistar rats decreased to 45% in 5 min after FB, and after 25 min it was approximately 40%. In Sprague-Dawley rats, the BSR was 55% immediately after the FB and it decreased steeply to reach 0% by 10 min. There was also a significant difference between the two strains in the frequency composition of the ECoG pattern. The power spectral densities of the two strains differed virtually throughout the post-ischemic state. The histological results (Evans Blue, Cresyl Violet and Fluoro Jade C stainings) supplemented the electrophysiological data: the neuronal damage in the CA1 pyramids in Wistar rats was severe, whereas in the Sprague-Dawley animals it was only partial. These observations clearly demonstrate that the use of different rat strains (e.g. Wistar vs. Sprague-Dawley) can be a source of considerable variability in the results of acute experiments on global ischemia and it is important that the laboratory rats used in such experiments should be carefully chosen.

High incidence of rhesus enteric calicivirus infections and diarrhea in captive juvenile macaques: a likely association

BACKGROUND

The rhesus enteric caliciviruses (ReCVs) were recently described.

METHODS

Prevalence of ReCV antibodies was tested in six species of captive non-human primates.

RESULTS

High ReCV seroprevalence was revealed in rhesus and cynomolgus macaques.

CONCLUSIONS

High rates of ReCV seroprevalence and diarrhea in juvenile macaques suggest that ReCVs may play a role in morbidity.

Molecular ABO phenotyping in cynomolgus macaques using real-time quantitative PCR

Macaques are commonly used in biomedical research as animal models of human disease. The ABO phenotype of donors and recipients plays an important role in the success of transplantation and stem cell research of both human and macaque tissue. Traditional serological methods for ABO phenotyping can be time consuming, provide ambiguous results and/or require tissue that is unavailable or unsuitable. We developed a novel method to detect the A, B, and AB phenotypes of macaques using real-time quantitative polymerase chain reaction. This method enables the simple and rapid screening of these phenotypes in macaques without the need for fresh blood or saliva. This study reports the distribution of the A, B, and AB phenotypes of captive cynomolgus macaques that, while regionally variable, closely resembles that of rhesus macaques. Blood group B, as in rhesus macaques, predominates in cynomolgus macaques and its frequency distribution leads to a probability of major incompatibility of 41%. No silencing mutations have been identified in exon 6 or 7 in macaques that could be responsible for the O phenotype, that, although rare, have been reported. The excess homozygosity of rhesus and cynomolgus macaque genotypes in this study, that assumes the absence of the O allele, suggests the possibility of some mechanism preventing the expression of the A and B transferases.

Molecular detection of murine noroviruses in laboratory and wild mice

Fecal specimens collected from 121 laboratory mice, 30 striped field mice (Apodemus agrarius), 70 yellow-necked mice (Apodemus flavicollis), and 3 bank voles (Myodes glareolus) were tested in sample pools for the presence of murine noroviruses (MNV). Ten of 41 laboratory mice and 2 of 3 striped field mice pooled samples were positive for MNV. All laboratory mouse MNVs were closely related to previously described MNVs. The complete ORF2 (VP1) of both striped field mouse MNVs identified in this study was 1623 nt (541 aa) long and differed at 12% nt (8% aa) positions from each other, at 22-24% nt (15-18% aa) positions from the laboratory mouse MNVs and at 20-22% nt (13-14% aa) positions from the recently described wood mouse (Apodemus sylvaticus) MNVs. This study provides further evidence for the circulation of novel, genetically diverse MNVs in wild mice.

Experimental inoculation of juvenile rhesus macaques with primate enteric caliciviruses

BACKGROUND

Tissue culture-adapted Tulane virus (TV), a GI.1 rhesus enteric calicivirus (ReCV), and a mixture of GII.2 and GII.4 human norovirus (NoV)-containing stool sample were used to intrastomacheally inoculate juvenile rhesus macaques (Macaca mulatta) in order to evaluate infection caused by these viruses. METHODOLOGY & FINDINGS: Two of the three TV-inoculated macaques developed diarrhea, fever, virus-shedding in stools, inflammation of duodenum and 16-fold increase of TV-neutralizing (VN) serum antibodies but no vomiting or viremia. No VN-antibody responses could be detected against a GI.2 ReCV strain FT285, suggesting that TV and FT285 represent different ReCV serotypes. Both NoV-inoculated macaques remained asymptomatic but with demonstrable virus shedding in one animal. Examination of duodenum biopsies of the TV-inoculated macaques showed lymphocytic infiltration of the lamina propria and villous blunting. TV antigen-positive (TV+) cells were detected in the lamina propria. In most of the TV+ cells TV co-localized perinuclearly with calnexin--an endoplasmic reticulum protein. A few CD20+TV+ double-positive B cells were also identified in duodenum. To corroborate the authenticity of CD20+TV+ B cells, in vitro cultures of peripheral blood mononuclear cells (PBMCs) from healthy macaques were inoculated with TV. Multicolor flow cytometry confirmed the presence of TV antigen-containing B cells of predominantly CD20+HLA-DR+ phenotype. A 2-log increase of viral RNA by 6 days post inoculation (p<0.05) suggested active TV replication in cultured lymphocytes.

CONCLUSIONS/SIGNIFICANCE

Taken together, our results show that ReCVs represent an alternative cell culture and animal model to study enteric calicivirus replication, pathogenesis and immunity.

Synthesis and biological effects of some kynurenic acid analogs

The overactivation of excitatory amino acid receptors plays a key role in the pathomechanism of several neurodegenerative disorders and in ischemic and post-ischemic events. Kynurenic acid (KYNA) is an endogenous product of the tryptophan metabolism and, as a broad-spectrum antagonist of excitatory amino acid receptors, may serve as a protective agent in neurological disorders. The use of KYNA is excluded, however, because it hardly crosses the blood-brain barrier. Accordingly, new KYNA analogs which can readily cross this barrier and exert their complex anti-excitatory activity are generally needed. During the past 6 years, we have developed several KYNA derivatives, among others KYNA amides. These new analogs included one, N-(2-N,N-dimethylaminoethyl)-4-oxo-1H-quinoline-2-carboxamide hydrochloride (KYNA-1), that has proved to be neuroprotective in several models. This paper reports on the synthesis of 10 new KYNA amides (KYNA-1-KYNA-10) and on the effectiveness of these molecules as inhibitors of excitatory synaptic transmission in the CA1 region of the hippocampus. The molecular structure and functional effects of KYNA-1 are compared with those of other KYNA amides. Behavioral studies with these KYNA amides demonstrated that they do not exert significant nonspecific general side-effects. KYNA-1 may therefore be considered a promising candidate for clinical studies.

From farm to fork follow-up of thermotolerant campylobacters throughout the broiler production chain and in human cases in a Hungarian county during a ten-months period

A study tracking thermotolerant campylobacters from the setting of the broilers throughout the whole rearing period, slaughter and sale of chicken products in five consecutive broiler rotations of the same henhouse as well as in two different other farms was conducted in a well-defined geographic area (Hajdú-Bihar county, Hungary) between March 2006 and Feb 2007. All notified cases of human campylobacteriosis in this area during the study period were also included. One hundred and one, 44, 23 and 282 Campylobacter jejuni and 13, 15, 20 and 60C. coli were isolated from broiler houses, slaughterhouses, retail shops and human samples, respectively. Sixty-two isolates collected from broilers or their environment selected from different flocks (57C. jejuni, 5C. coli), 92 isolates collected from abattoirs and retail shops (72C. jejuni, 20C. coli), as well as 85 randomly selected human isolates (74C. jejuni, 11C. coli) were subjected to PFGE analysis using restriction enzymes KpnI and SmaI. Sixty-six of the isolates produced unique Sma-Kpn profiles; the majority (46) of these were of human origin. The remaining isolates formed PFGE clusters of between 2-25 isolates with 14 (12C. jejuni and 2C. coli) main clusters comprised of five or more isolates with identical KpnI-SmaI patterns. Two genetic clones of C. jejuni (clone A, n=25; clone B, n=20) included 18% of isolates from different sources. Generally, isolates from one cluster were found in 1-3 different flocks, notably, clone B was present in three rotations including those from the two independent farms. Six of the seven investigated flocks had one or two characteristic prevalent clones. Transmission of clones between consecutive flocks was frequently seen. Spread of both C. jejuni and C. coli was traced multiple times along the food chain; eight C. jejuni, but no C. coli clones were detected both in broilers and humans. These data suggest that broilers were the major source for C. jejuni but not for C. coli in the studied area and period. For C. jejuni the carryover of strains between consecutive flocks may be a common event, but the strain is eventually replaced by another and consecutive carryover events seem to be infrequent. The majority of the human disease was due to nonepidemic strains; some clones were transmitted from more than one broiler flocks (including epidemiologically unrelated flocks) to humans multiple times.

Detection and follow-up of torque teno midi virus ("small anelloviruses") in nasopharyngeal aspirates and three other human body fluids in children

Torque teno midi virus/small anellovirus (TTMDV/SAV) is a member of the family Anelloviridae. It has a single-stranded, circular, negative-sense DNA genome. Its pathogenic role in human disease remains to be confirmed. In this study, viral shedding, molecular epidemiology and genetic diversity of TTMDV/SAV were studied in human body fluids. Nasopharyngeal aspirates collected from children with acute respiratory disease were tested by PCR/nested PCR for TTMDV/SAV in two seasons (2005/2006, 2006/2007). Two years later, additional urine, stool, and serum samples and nasopharyngeal aspirates were collected from eight symptomless children for follow-up investigation. Forty-three (46.7%) of the 92 nasopharyngeal aspirates collected contained TTMDV/SAV. High genetic diversity was observed; however, identical sequences were also detected in two patients. The mean age of the infected children was 3 years (1 months-8 years), and 58% of them were female. Co-infection with RSV was detected in 23% of the samples. In a follow-up study, nasopharyngeal aspirates and serum of six (75%), stool samples of four (50%) and urine samples of two (25%) of the eight children were anellovirus-positive. None of the anellovirus sequences were identical in the two collection periods, but identical sequences were detected in different body fluids collected at the same time from the same child. TTMDV/SAVs shedding was detected in four human body fluids. As a consequence, it is possible that generalized infection and fecal/uro-oral transmission of TTMDV/SAV occur. TTMDV/SAVs are frequently present in nasopharyngeal aspirates, although the variants may only be transient agents. Further research is needed to investigate the pathogenesis and pathogenic role of TTMDV/SAV.

Composition and Biophysical Properties of Lipids in Xenorhabdus nematophilus and Photorhabdus luminescens, Symbiotic Bacteria Associated with Entomopathogenic Nematodes

Primary and secondary forms of Photorhabdus luminescens Hm and Xenorhabdus nematophilus N2-4 were grown at 18 and 28(deg)C for 24 to 96 h, and we made determinations of the fatty-acid compositions of total lipids and of the fluidity measured by 5-doxyl-stearic acid embedded in liposomes made from total lipids. The levels of the unsaturated fatty acids 16:1 and 18:1 (those with chain lengths of 16 or 18 and one double bond) generally were higher in primary-phase variants of P. luminescens grown at 18(deg)C than in those grown at 28(deg)C. Prolonged culture at 18(deg)C caused the level of 18:1 to fall and reach that observed at 28(deg)C. The ratio of saturated to unsaturated fatty acids rose with prolonged culture times in variants of each species at both phases. When grown at 18(deg)C, the proportion of 16:1 in X. nematophilus was lower than in P. luminescens; the patterns of temperature-induced changes were similar in these species. X. nematophilus contained a greater percentage of short-chain fatty acids (i.e., with chain lengths of <14.0) than P. luminescens. Lipid liposomes from primary and secondary cultures of both bacterial species grown at 18(deg)C were more ordered (i.e., less fluid) than those grown at 28(deg)C. This result suggests the surprising absence of homeoviscous adaptation of membranes to temperature. Also, liposomes from primary cultures were more ordered than those from secondary cultures and membranes from primary cultures of P. luminescens were more ordered at both culture temperatures than membranes from X. nematophilus. The biological significance of the effect of growth conditions on membrane biophysical properties in these bacteria is discussed.

Surveillance and risk factors of norovirus gastroenteritis among children in a southern city of China in the fall-winter seasons of 2003-2006

AIM

Noroviruses (NoVs) are an important cause of acute gastroenteritis but knowledge on the disease burden and epidemiology in children in the developing countries remains limited. In this study, we performed a surveillance of NoV gastroenteritis in children of China to address some of the questions.

METHODS

Faecal specimens from children (<5 years of age) at outpatient clinics of the Nan Fang Hospital in Guangzhou, China during the fall-winter seasons in 2003-2006 were tested for rotaviruses (RVs) and NoVs. A questionnaire on clinical records and hygiene habits was collected from each patient.

RESULTS

Among 957 stool specimens tested, 488 (51%) specimens were positive for RVs. NoVs were detected in 112 (24%) of the 469 RV negative specimens. The Genogroup II (GII), particularly GII-4, viruses were predominant. No significant difference of clinical symptoms, hospitalisation and patient care expenses were found between children infected with NoVs and RVs. Consumption of uncooked food is a risk for NoV infection. Contact with diarrhoea patients is a suspected risk factor. Cutting nails frequently is a protective factor against NoV infection.

CONCLUSIONS

NoVs are an important cause of acute gastroenteritis in children which need special attention of patient care at the clinics in addition to RVs. The awareness of those risk factors may help future disease control and prevention.

Detection of norovirus-, sapovirus- and rhesus enteric calicivirus-specific antibodies in captive juvenile macaques

The objective of this study was to determine the prevalence of anti-norovirus (NoV), -sapovirus (SaV) and -Tulane virus (TV) antibodies in rhesus macaques of the Tulane National Primate Research Center and to evaluate the antigenic relationship between these viruses. A high prevalence of NoV-binding (51-61 %) and SaV-binding (50-56 %) antibodies and TV-neutralizing (69 %) antibodies were detected. Serum samples obtained during a human NoV outbreak and a multivalent anti-NoV hyperimmune serum were not able to neutralize TV infectivity. Conversely, low levels of cross-reactivity between the prototype TV and NoVs, but not between the TV and SaVs were detected by ELISA. These data indicate the preservation of some cross-reactive B-cell epitopes between the rhesus and human caliciviruses (CVs). The high prevalence of human and rhesus CV-specific serum antibodies suggests the frequent exposure of colony macaques to enteric CVs including the possibility of CV transmission between human and non-human primate hosts.

Concurrent cryptosporidiosis and chicken anaemia virus infection in broiler chickens

Concurrent infection with Cryptosporidium baileyi and chicken anaemia virus (CAV) was observed in a flock of 8000 4-week-old broiler chickens. The birds, showing overt symptoms of stunted growth and 25% mortality from hatching to 4 weeks of age, harboured the protozoan in the epithelial cells of the bursa of Fabricius and the urodeal portion of the cloaca. This is the first report on an outbreak of avian cryptosporidiosis associated with CAV.

Elucidation of strain-specific interaction of a GII-4 norovirus with HBGA receptors by site-directed mutagenesis study

Noroviruses interact with histo-blood group antigen (HBGA) receptors in a strain-specific manner probably detecting subtle structural differences in the carbohydrate receptors. The specific recognition of types A and B antigens by various norovirus strains is a typical example. The only difference between the types A and B antigens is the acetamide linked to the terminal galactose of the A but not to the B antigen. The crystal structure of the P dimer of a GII-4 norovirus (VA387) bound to types A and B trisaccharides has elucidated the A/B binding site on the capsid but did not explain the binding specificity of the two antigens. In this study, using site-directed mutagenesis, we have identified three residues on the VA387 capsid that are sterically close to the acetamide and are required for binding to A but not B antigens, indicating that the acetamide determines the binding specificity between the A and B antigens. Further mutational analysis showed that a nearby open cavity may also be involved in binding specificity to HBGAs. In addition, a systematic mutational analysis of residues in and around the binding interface has identified a group of amino acids that are required for binding but do not have direct contact with the carbohydrate antigens, implying that these residues may be involved in the structural integrity of the receptor binding interface. Taken together, our study provides new insights into the carbohydrate/capsid interactions which are a valuable complement to the atomic structures in understanding the virus/host interaction and in the future design of antiviral agents.

Novel PCR assay for identification of Salmonella enterica serovar Infantis

AIMS

We developed, optimized and tested two novel PCR assays specific for Salmonella enterica subspecies enterica serovar Infantis.

METHODS AND RESULTS

The fljB gene was chosen as the target sequence. Primers were designed on a consensus sequence built by sequencing the fljB gene of five genetically unrelated Hungarian S. Infantis strains and using sequence data from the GenBank (http://www.ncbi.nih.gov). Two alternative assays were designed, which share the reverse primer. Both proved to be highly specific to S. Infantis, neither reacted with 42 other nontyphoidal serovariants tested. The detection limit of the assays was determined to be 10(5) CFU ml(-1) from pure culture, and 10(6) CFU g(-1) from artificially spiked chicken faeces samples.

CONCLUSIONS

Although the detection limit is rather high to allow for using them for direct detection, the assays may be useful in identification of S. Infantis both for diagnostic and for research purposes.

SIGNIFICANCE AND IMPACT OF THE STUDY

The described PCR assays allow for the correct identification of S. Infantis even when traditional serotyping methods fail because lack of expression of flagellar antigens.

Real-time reverse transcription-polymerase chain reaction detection of Newcastle disease virus using light upon extension fluorogenic primers

A real-time reverse transcriptase (RT)-PCR assay, applying light upon extension (LUX) fluorogenic primers, was developed for rapid and efficient detection of Newcastle disease virus (NDV). The method, which targets the fusion (F) protein gene of the viral genome, gave positive signal with all NDV isolates tested (32/32), while negative results were obtained with heterologous pathogens (35/35), including 13 avian influenza virus isolates. The detection limit of the assay was approximately 10(+1.2) egg infectious dose (EID)(50)/0.2 ml and 10(+2.2) EID(50)/0.2 ml for virus suspensions and spiked chicken fecal samples, respectively. As expressed in plasmid copy number, the procedure has a sensitivity of approximately 20 copies of the plasmid harboring the target gene. Due to its high specificity, sensitivity, and relative simplicity, the LUX RT-PCR assay provides a novel, rapid, and practical tool for the detection of NDV.

Rapid and Simultaneous Detection of Avian Influenza and Newcastle Disease Viruses by Duplex Polymerase Chain Reaction Assay

A duplex reverse transcription-polymerase chain reaction (dRT-PCR) assay has been developed for the simultaneous, rapid and specific detection/discrimination of avian influenza virus (AIV) and Newcastle disease virus (NDV). Primers targeting the matrix protein gene (M) of AIV and the fusion protein gene (F) of NDV were evaluated experimentally with 13 AIV and 19 NDV strains. PCR products of the expected size of 144 bp and 316 bp were amplified from AIV/NDV samples, respectively, while no cross-reaction was observed with negative controls or with 16 other avian pathogens. The endpoint of detection was defined as approximately 10(+0.5) 50% egg infectious dose (EID(50))/0.2 ml for AIV and 10(+2.2) EID(50)/0.2 ml for NDV. The assay was able to detect AIV/NDV with similar sensitivity in spiked stool samples and in specimens from vaccinated birds. The developed dRT-PCR assay is a rapid, cost-effective tool, which provides powerful novel means for the early diagnosis of avian influenza and Newcastle disease.

Application of real-time RT-PCR utilising lux (light upon extension) fluorogenic primer for the rapid detection of avian influenza viruses

A real-time RT-PCR assay utilising light upon extension fluorogenic primer (LUX RT-PCR) was developed for the rapid and efficient detection of avian influenza viruses (AIV). The assay detected each of the AIV isolates tested (16/16) and gave negative results with heterologous pathogens (17/17). The detection limit of the assay proved to be 10(-0.5) EID50/0.2 ml and 10(1.5) EID50/0.2 ml in allantoic fluid of virus-infected embryonated chicken eggs and in spiked chicken faeces samples, respectively. Based on its specificity, sensitivity and relative simplicity, the LUX RT-PCR assay provides a novel, rapid and cost-effective diagnostic tool for avian influenza surveillance and monitoring programs.

Development of an enzyme immunoassay for detection of sapovirus-specific antibodies and its application in a study of seroprevalence in children

Sapoviruses (SVs) are an important cause of acute pediatric gastroenteritis. Due to the lack of appropriate diagnostic methods, the epidemiology of SV-associated illness remains poorly understood. Baculovirus and Escherichia coli expression systems were evaluated for the development of antibody detection enzyme immunoassays (EIA). Age-related antibody prevalence in children was studied using the new EIA. Because of the low yield of the baculovirus system, the E. coli-expressed SV capsid proteins were used to develop the EIA. The antigenic specificities of the E. coli-expressed SV capsid proteins were demonstrated using hyperimmune antisera raised in animals and sera collected from patients. A high prevalence (>90%) of antibodies to both SV (strain Mex340) and norovirus (strain VA387) was observed in children involved in a birth cohort at 20 to 24 months of age; however, at 1 to 3 months of age, <25% of the children possessed anti-SV antibodies versus >90% with anti-NV antibodies. The E. coli-derived SV proteins are an excellent source of antigens for the EIA. SV infection is common in the first 2 years of life. The low prevalence of maternal antibodies detected in Mexican children against SVs in this study is unique and needs to be addressed in future studies.

Norovirus capsid protein expressed in yeast forms virus-like particles and stimulates systemic and mucosal immunity in mice following an oral administration of raw yeast extracts

Norovirus (NV) gastroenteritis is a widespread disease affecting people of all ages worldwide. A simple, safe, and easily deliverable vaccine may be the key for the control and prevention of NV gastroenteritis. In this study, we demonstrated that a NV recombinant capsid protein (strain VA387, genogroup II.4) expressed in yeast (Pichia pastoris) spontaneously formed virus-like particles (VLPs) like those expressed in other in vitro systems. Oral administration of raw material from the yeast cell lysates containing 0.1 mg of VLPs without an adjuvant resulted in systemic and mucosal immune responses in mice. Significantly higher and earlier responses were observed in mice receiving a higher dose (1 mg per dose) of the antigen. Both the serum and fecal antibodies blocked VA387 VLP binding to its histo-blood group antigen receptors. The animals did not reveal any side effect following the administration of the yeast lysates. Our results indicated that yeast is a simple, effective alternative for NV VLP production. The mice immunization study also indicated that the oral administration of raw yeast extracts without an adjuvant is a safe and simple way which is worth to be studied for vaccine delivery in humans.

Seroprevalence of noroviruses in swine

Noroviruses (NVs) are important human pathogens that cause acute gastroenteritis. Genetically related animal enteric NVs have also been described, but there is no evidence of interspecies transmission of NVs. In this study we characterized antibody prevalence among domestic pigs by using recombinant capsid antigens of two human NVs (Norwalk and Hawaii) and one swine NV (SW918) that is genetically related to GII human NVs. Recombinant SW918 capsid protein expressed in baculovirus self-assembled into virus-like particles (VLPs) that were detected by antibodies against GII (Hawaii and Mexico), but not GI (Norwalk and VA115), human NVs. NVs recognize human histo-blood group antigens as receptors, but SW918 VLPs did not bind to human saliva samples with major histo-blood group types. Seventy-eight of 110 (71%) pig serum samples from the United States and 95 of 266 (36%) pig serum samples from Japan possessed antibodies against SW918. Serum samples from pigs in the United States were also tested for antibodies against human NVs; 63% were positive for Norwalk virus (GI) and 52% for Hawaii virus (GII). These results indicate that NV infections are common among domestic pigs; the finding of antigenic relationships between SW918 and human NVs and the detection of antibodies against both GI and GII human NVs in domestic animals highlights the importance of further studies on NV gastroenteritis as a possible zoonotic disease.

Norovirus and histo-blood group antigens: demonstration of a wide spectrum of strain specificities and classification of two major binding groups among multiple binding patterns

Noroviruses, an important cause of acute gastroenteritis, have been found to recognize human histo-blood group antigens (HBGAs) as receptors. Four strain-specific binding patterns to HBGAs have been described in our previous report. In this study, we have extended the binding patterns to seven based on 14 noroviruses examined. The oligosaccharide-based assays revealed additional epitopes that were not detected by the saliva-based assays. The seven patterns have been classified into two groups according to their interactions with three major epitopes (A/B, H, and Lewis) of human HBGAs: the A/B-binding group and the Lewis-binding group. Strains in the A/B binding group recognize the A and/or B and H antigens, but not the Lewis antigens, while strains in the Lewis-binding group react only to the Lewis and/or H antigens. This classification also resulted in a model of the norovirus/HBGA interaction. Phylogenetic analyses showed that strains with identical or closely related binding patterns tend to be clustered, but strains in both binding group can be found in both genogroups I and II. Our results suggest that noroviruses have a wide spectrum of host range and that human HBGAs play an important role in norovirus evolution. The high polymorphism of the human HBGA system, the involvement of multiple epitopes, and the typical protein/carbohydrate interaction between norovirus VLPs and HBGAs provide an explanation for the virus-ligand binding diversities.

Pentapeptides derived from Aβ1–42 protect neurons from the modulatory effect of Aβ fibrils—an in vitro and in vivo electrophysiological study

Short fragments and fragment analogues of beta-amyloid 1-42 peptide (Abeta1-42) display a protective effect against Abeta-mediated neurotoxicity. After consideration of our earlier results with in vitro bioassay of synthetic Abeta-recognition peptides and toxic fibrillar amyloids, five pentapeptides were selected as putative neuroprotective agents: Phe-Arg-His-Asp-Ser amide (Abeta4-8) and Gly-Arg-His-Asp-Ser amide (an analogue of Abeta4-8), Leu-Pro-Tyr-Phe-Asp amide (an analogue of Abeta17-21), Arg-Ile-Ile-Gly-Leu amide (an analogue of Abeta30-34), and Arg-Val-Val-Ile-Ala amide (an analogue of Abeta38-42). In vitro electrophysiological experiments on rat brain slices demonstrated that four of these peptides counteracted with the field excitatory postsynaptic potential-attenuating effect of Abeta1-42; only Arg-Val-Val-Ile-Ala amide proved inactive. In in vivo experiments using extracellular single-unit recordings combined with iontophoresis, all these pentapeptides except Arg-Val-Val-Ile-Ala amide protected neurons from the NMDA response-enhancing effect of Abeta1-42 in the hippocampal CA1 region. These results suggest that Abeta recognition sequences may serve as leads for the design of novel neuroprotective compounds.

Gastroenteritis in US Marines during Operation Iraqi Freedom

BACKGROUND

Approximately 83,000 US Marines participated in the opening phase of Operation Iraqi Freedom in Spring 2003. A Navy Preventive Medicine laboratory was set up in Ad Diwaniyah, Iraq, to provide clinical diagnostic support for Marine medical units during a period of repositioning in south-central Iraq.

METHODS

Specimen collection boxes were sent to >30 primary care medical stations handling 500-900 personnel each. The laboratory had capability to detect many different disease agents, especially those causing febrile illness. Diarrheal stool diagnostic evaluation included plating and biochemical identification, antigen serologic testing, fluorescent antibody antigen detection, disk diffusion antimicrobial susceptibility testing, enzyme immunoassay, and reverse-transcriptase polymerase chain reaction for norovirus (NV). Confirmation and sequencing work for NV was done at Cincinnati Children's Hospital Medical Center (Ohio).

RESULTS

By far the most common reason for infectious disease sick call visits was gastrointestinal illness; no other symptoms had equivalent impact. An enteropathogen was detected in 57 (44%) of 129 stool samples, with NV detected in 30 stool samples (23%) obtained from 14 different battalion or similar-sized units; next in frequency were Shigella flexneri and Shigella sonnei, which were isolated from 26 stool samples (20%) obtained from 15 units. Sequencing the NV RNA polymerase gene demonstrated that NV strains represented 7 genetic clusters, including 2 strains from genogroup I and 5 from genogroup II. Ciprofloxacin was effective in vitro against most bacterial agents, but neither doxycyline (which was taken daily as the antimalarial prophylaxis dose) nor trimethoprim-sulfamethoxazole were effective.

CONCLUSIONS

Multiple strains of Shigella species and NV predominated, probably because they do not require a large inoculum to cause infection. Otherwise, personnel remained free of infectious illness during this phase of the conflict, because other infectious agents were rare or absent.

Seroprevalence of antibodies against noroviruses among students in a Chinese military medical university

Noroviruses (NVs) are important causes of nonbacterial gastroenteritis in humans, but the role of NVs as a cause of diseases in the Chinese people, particularly in Chinese military personnel, remains unclear. This study investigated antibody prevalence and factors that associate with the prevalence of antibody to NVs among students attending a military medical university. Serum specimens were tested by an enzyme-linked immunosorbent assay for immunoglobulin G antibody to recombinant capsid antigens of three NVs (rNorwalk, rMxV, and rVA387). Of 588 serum samples tested, the antibody prevalence was 88.9, 54.1, or 90.0% for the three antigens, respectively. There were significant differences in the prevalence of antibody to rMxV between blood types (P < 0.05); the prevalence for type O was the highest (62.5%), and the prevalence for type B was the lowest (49.1%). The average optical density values for antibody to rNorwalk and rMxV were lowest among students with type B. The number of students who did not have antibody to any of the three antigens was the highest for blood type B (6.9%) compared to other blood types (0.8 to 3.4% [P < 0.006]). The antibody prevalence also varied with the hometown residencies of the students before joining the military, with the highest rates for students from rural areas, lower rates for students from small towns or villages, and the lowest rates for students from large cities. The numbers of students who did not have antibody to any of the three antigens were highest for students from the large cities, lower for students from small towns or villages, and lowest for students from rural areas. The distribution of ABO blood types did not differ among the three groups. These data suggest that NVs are prevalent in China and that both genetic and environmental factors play a role in NV infection.

Kynurenine administered together with probenecid markedly inhibits pentylenetetrazol-induced seizures. An electrophysiological and behavioural study

The kynurenine pathway converts tryptophan into various compounds, including l-kynurenine, which in turn can be converted to the excitatory amino acid receptor antagonist kynurenic acid, which may therefore serve as a protective agent in such neurological disorders as epileptic seizures. Kynurenic acid, however, has a very limited ability to cross the blood-brain barrier, whereas kynurenine passes the barrier easily. In this study, we tested the hypothesis that kynurenine administered systemically together with probenecid, which inhibits kynurenic acid excretion from the cerebrospinal fluid, results in an increased level of kynurenic acid in the brain that is sufficiently high to provide protection against the development of pentylentetrazol-induced epileptic seizures. CA3 stimulation-evoked population spike activity was recorded from the pyramidal layer of area CA1 of the rat hippocampus, and in another series of behavioural experiments, water maze and open-field studies were carried out to test the presumed protective effect of kynurenine + probenecid pre-treatment against pentylenetetrazol-induced seizures. This study has furnished the first electrophysiological proof that systemic kynurenine (300 mg/kg, i.p.) and probenecid (200 mg/kg, i.p.) administration protects against pentylenetetrazol-induced (60 mg/kg, i.p.) epileptic seizures.