Prospective multicentre study of rectal carriage of multidrug-resistant Enterobacteriaceae among health-care workers in Spain

OBJECTIVES

To investigate the rectal carriage of multidrug-resistant Enterobacteriaceae (colistin-resistant, extended-spectrum β-lactamase (ESBL) -producers and/or carbapenemase-producers) among health-care workers (HCWs) from six Spanish hospitals.

METHODS

Rectal swabs from 258 HCWs, employed in intensive care units, haematology wards and clinical microbiology laboratories from six hospitals in northern Spain were studied. They were cultured in selective media for Gram-negative resistant bacteria. Detection of antimicrobial resistance genes and multilocus sequence typing were performed by PCR and further sequencing. A questionnaire including data related to risk factors of colonization/infection by resistant bacteria (age, gender, chronic diseases, immunosuppressive therapies, invasive procedures or antimicrobial treatments) was given to each participant.

RESULTS

No carbapenemase-producing Enterobacteriaceae were recovered. However, 8/258 HCWs (3.1%) were positive for ESBL-producing isolates. This rate was not higher than the colonization rate previously reported in Spain for healthy people in the community. Five isolates showed high-level resistance to colistin (MICs ranging from 8 to 128 mg/L) but all of them were negative for the mcr genes tested. No statistically significant risk factors for gut colonization by ESBL-producing or colistin-resistant Enterobacteriaceae were identified among the HCWs participating in the study.

CONCLUSIONS

Our data suggest that working in hospitals does not represent a risk for rectal carriage of multidrug-resistant Enterobacteriaceae.

Clostridium difficile presence in Spanish and Belgian hospitals

Clostridium difficile is recognised worldwide as the main cause of infectious bacterial antibiotic-associated diarrhoea in hospitals and other healthcare settings. The aim of this study was to first survey C. difficile prevalence during the summer of 2014 at the Central University Hospital of Asturias (Spain). By typing the isolates obtained, it was then possible to compare the ribotype distribution at the Spanish hospital with results from the St Luc University Hospital in Belgium over the same period. The prevalence of positive cases reported in Spain and Belgium was 12.3% and 9.3% respectively. The main PCR-ribotypes previously described in Europe were found in both hospitals, including 078, 014, 012, 020 and 002. In the Spanish hospital, most of the C. difficile-positive samples were referred from oncology, acute care and general medicine services. In the Belgian hospital the majority of positive samples were referred from the paediatric service. However, a high percentage of isolates from this service were non-toxigenic. This study finds that the presence and detection of C. difficile in paediatric and oncology services requires further investigation.

Trypanosoma cruzi infection in a Spanish liver transplant recipient

The shortage of suitable organ donors for transplantation has stimulated the use of organs from donors with transmissible infections such as Chagas disease in noninfected recipients. A case is described of liver transplantation from an anti-Trypanosoma cruzi-positive donor to a noninfected recipient who showed favorable evolution despite not having undergone preemptive therapy.

Autophagic and proteolytic processes in the Harderian gland are modulated during the estrous cycle

The Syrian hamster Harderian gland (HG) is an organ that undergoes physiological autophagy in response to oxidative stress induced by porphyrin production. Porphyrin production in the HG has marked sex differences and is closely linked to reproductive function. In the present study, we observed that the estrous cycle and associated estrogen variations may affect oxidative-stress-induced proteolytic processes. In particular, significant changes in autophagic activity were detected during the estrous cycle. Notably, increased activation of macroautophagy as well as chaperone-mediated autophagy in the estrus phase coincided with a minimal antioxidant capability and the highest protein damage levels. By contrast, autophagic machinery was found to be blocked in the diestrus phase, likely due to mammalian target of rapamycin activation, which could be corroborated by the subsequent pS6K activation. Analogous results were observed regarding proteasome activity, which also showed maximal activity in the estrus phase. Interestingly, all these mechanisms were associated with important morphological changes in the HG during the estrous cycle. We observed statistically significant increases in Type II cells, which may be related to extensive autophagy in the estrus phase. Physiologically, this would result in a significant release of porphyrins specifically when females are more receptive. These data support the role of porphyrins as pheromones, as other authors have previously suggested, thus making the HG a scent organ. In addition, these results suggest a porphyrin-based approach to the treatment of porphyria during pregnancy, a condition for which no treatment is currently known.

Genotyping Chlamydia trachomatis strains among men who have sex with men from a Northern Spain region: a cohort study

OBJECTIVES

To determine the prevalence of anorectal Chlamydia trachomatis serovars in a group of men who have sex with men (MSM) with high risk sexual behaviour, attendees at a sexually transmitted infection (STI) unit from a region in Northwest Spain.

DESIGN

Retrospective and descriptive study of all swabs obtained from all MSM attendees at an STI unit, from 2007 to 2011. Retrospective ethical approval was granted by the Ethical Regional Committee of Clinical Investigation of the Principality of Asturias.

SETTING

The STI clinic in Oviedo, Spain, offers screening and free-of-charge treatment to about 3646 patients per year.

PARTICIPANTS

303 symptomatic and asymptomatic consecutive and unselected MSM patients (mean age 36.7 and range 21-55 years) were evaluated for anorectal chlamydial infection.

MAIN OUTCOME MEASURES

C trachomatis DNA extraction and detection in all rectal and in 36 urethral swabs. Characterisation of C trachomatis genotypes through sequencing of ompA gene amplicons and further phylogenetic tree analysis.

RESULTS

We found 40 (13. 2%) positive rectal samples. The distribution of genotypes was E (37. 5%) followed by G (25%), D (12. 5%), J (10%) and L2b (5%).25 (62.5%, 95% CI 46.2 to 78.7) of the chlamydia-infected MSM showed clinical manifestations while 15 (37.5%, 95% CI 21.25 to 53.75) reported no symptoms. Concurrent infection with other STIs was documented in 27 (67.5%, 95% CI 51.7 to 83.2) patients. The most frequently reported clinical symptom was anal ulcer (7 cases, 17.5%; 95% CI 4.47 to 30.52). E genotype was mostly detected in asymptomatic patients. There were non-E genotypes detected in 21 (84%, 95% CI 63.9 to 95.5) of 25 symptomatic patients (p<0.001).

CONCLUSIONS

The first two confirmed cases of lymphogranuloma venereum (LGV) in MSM in Asturias are reported, probably indicating the increase of this infection. The Spanish C trachomatis laboratory-based surveillance system may underlie an underestimated number of chlamydial infections. Whenever mild and atypical symptoms exist, laboratory evaluation would contribute to the early implementation of appropriate therapy and prevent LGV dissemination.

The photoperiod, circadian regulation and chronodisruption: the requisite interplay between the suprachiasmatic nuclei and the pineal and gut melatonin

The current scientific literature is replete with investigations providing information on the molecular mechanisms governing the regulation of circadian rhythms by neurons in the suprachiasmatic nucleus (SCN), the master circadian generator. Virtually every function in an organism changes in a highly regular manner during every 24-hour period. These rhythms are believed to be a consequence of the SCN, via neural and humoral means, regulating the intrinsic clocks that perhaps all cells in organisms possess. These rhythms optimize the functions of cells and thereby prevent or lower the incidence of pathologies. Since these cyclic events are essential for improved cellular physiology, it is imperative that the SCN provide the peripheral cellular oscillators with the appropriate time cues. Inasmuch as the 24-hour light:dark cycle is a primary input to the central circadian clock, it is obvious that disturbances in the photoperiodic environment, e.g., light exposure at night, would cause disruption in the function of the SCN which would then pass this inappropriate information to cells in the periphery. One circadian rhythm that transfers time of day information to the organism is the melatonin cycle which is always at low levels in the blood during the day and at high levels during darkness. With light exposure at night the amount of melatonin produced is compromised and this important rhythm is disturbed. Another important source of melatonin is the gastrointestinal tract (GIT) that also influences the circulating melatonin is the generation of this hormone by the entero-endocrine (EE) cells in the gut following ingestion of tryptophan-containing meal. The consequences of the altered melatonin cycle with the chronodisruption as well as the alterations of GIT melatonin that have been linked to a variety of pathologies, including those of the gastrointestinal tract.

Clinical characteristics of nosocomial and community-acquired extraintestinal infections caused by Hafnia alvei

36 episodes (25 nosocomial and 11 community-acquired) of infections caused by Hafnia alvei showed that this bacterium is responsible for serious infections in adults, specially in hospitalized patients with underlying chronic diseases, subjected to invasive procedures or even under antibiotic treatment.

Molecular identification of two genotypes of mumps virus causing two regional outbreaks in Asturias, Spain

BACKGROUND

In spite of universal vaccination, several sporadic cases of mumps infection, which could produce outbreaks, are detected every year in different countries.

OBJECTIVE

Mumps virus strains causing two regional outbreaks in Asturias (Spain) were phylogenetically characterized.

STUDY DESIGN

Mumps virus strains, which were detected in samples from patients belonging to two regional outbreaks in Asturias, were characterized by sequencing of the SH gene and further alignment to homologous sequences of representative strains of the different mumps genotypes.

RESULTS

Two different strains (Ast/SP02 and Ast/SP07) were isolated. Sequence analysis revealed that while Ast/SP02 belonged to genotype H, Ast/SP07 was phylogenetically close to UK02-19, a reference strain for a new genotype. Both strains belonged to different genotypes from those used in the vaccination (Jeryl-Lynn strain is genotype A).

CONCLUSION

Mumps virus strains different from those used in vaccination program can cause mumps outbreaks even in vaccinated patients.

Hepatitis C virus reactivation in anti-hepatitic C virus-positive renal transplant recipients

From 1992 to 2001 hepatitis C virus (HCV) viremia was studied in 53 renal transplant recipients anti-HCV+ with at least 3 months follow-up posttransplant using a quantitative retrotranscriptase-PCR method. HCV-RNA was detected in 45 (85%): 29 of the 34 recipients treated with azathioprine-based therapy and 15 of 18 treated with mycophenolate mofetil. Immunosuppressive therapy type did not affect HCV replication. Three different patterns of HCV-RNA evolution were detected: 13 (28.8%) patients with high RNA-HCV levels; 21 (46.7%) patients with low levels; and 11 (24.4%) patients with viremia elevation. In 10 (90%) of 11 of the last group, HCV viremia was detected before 15 days posttransplantation, significantly earlier than in the other two groups. Thus, replication during the first 15 days after transplantation leads to a high RNA-HCV viral load. No clinical symptoms were related to HCV.

Influence of Ganciclovir Prophylaxis on Citomegalovirus, Human Herpesvirus 6, and Human Herpesvirus 7 Viremia in Renal Transplant Recipients

In order to know the influence of ganciclovir (GCV) prophylaxis on cytomegalovirus (CMV) human herpesvirus (HHV)-6 and HHV-7 replication in renal transplant recipients, three groups were studies: 54 patients without GCV; 29, with short-term GCV prophylaxis (less than 30 days); and 51, with long-term GCV prophylaxis (more than 60 days). CMV viremia was more prevalent in the first group (74%, 55%, and 29%, respectively), but CMV replication was also found in 14 patients during therapy, in the other two groups. The antiviral did not affect the prevalence of HHV-6 (67.2%) or HHV-7 (76%), but HHV-6 viremia appeared later (42 +/- 31 vs 21 +/- 25/38 +/- 29 days posttransplant) and was shorter (29 +/- 30 vs 62 +/- 34/41 +/- 33 days) among patients with long-term GCV prophylaxis. On the other hand, CMV viremia was longer when HHV-6 replication was present (40 +/- 25 days vs 18 +/- 16 days). In addition, HHV-7 DNA was detected in all patients with CMV disease.

Involvement of adenovirus in clinical mononucleosis-like syndromes in young children

Although Epstein-Barr virus (EBV) commonly causes infectious mononucleosis (IM) or IM-like syndromes, other agents can be implicated. In this study, viral and parasitic screening was performed to determine the etiological agent of pediatric IM-like syndromes in 38 children. Adenovirus was the agent most frequently detected (47.3%), followed by EBV (31.5%) and cytomegalovirus (2.6%). Although the statistically significant difference between viral detection rates observed in patients who fulfilled clinical and hematological criteria and detection rates in those who presented clinical symptoms only (91.6% vs. 64.3%) indicates that hematological abnormalities are common in viral IM-like syndromes, the existence of syndromes of viral etiology without hematological criteria cannot be discarded. A further analysis showed an absence of lymphocytosis in adenovirus infections as well as a low number (14.3%) of EBV infections associated with increased neutrophils. These data suggest the usefulness of appropriate virological techniques for the detection of adenovirus in pediatric IM-like syndromes.

Porphyric enzymes in hamster Harderian gland, a model of damage by porphyrins and their precursors. A chronobiological study on the role of sex differences

The Syrian hamster Harderian gland (HG), representing a highly porphyrogenic organ, was used as a model system for studying physiologically occurring damage of biomolecules by porphyrins and their precursors, phenomena associated with from the pathological situation of porphyrias. The species used exhibits the peculiarity of much higher porphyrogenesis in females than in males, offering possibilities for comparison of effects by different porphyrin levels in one species. Since concentrations of free, and therefore, radical-generating porphyric metabolites are difficult to determine in the presence of high amounts of secreted and crystallizing porphyrins, which are, moreover, mainly surface-reactive, and since indications existed for temporal changes in the oxidative stress caused by these molecules, the following approach was chosen: in HGs of both females and males, activities of the relevant porphyric enzymes, delta-aminolevulinate synthase (ALA-S), delta-aminolevulinate dehydratase (ALA-D) and porphobilinogen deaminase (PBG-D), were determined throughout the circadian cycle. Results were compared with the temporal patterns of lipid peroxidation and protein damage in the same glands. In females, a strong correspondence was observed between protein carbonyl and lipid peroxidation, peaking at the end of both photophase and scotophase; maximal activities of the three porphyric enzymes ALA-S, ALA-D, and PBG-D either coincided or slightly preceded the peaks of oxidative damage. In males, lower enzyme activities, especially in PBG-D, were associated with weakly expressed rhythmicity. Correspondingly, lipid peroxidation was lower and exhibited a smaller rhythm amplitude; protein carbonyl of males showed a temporal pattern differing from that of females, with regard to amplitude and phasing. These data are in agreement with morphological observations demonstrating particularly severe cell damage in the female HG under normal conditions.

Physiological oxidative stress model: Syrian hamster Harderian gland-sex differences in antioxidant enzymes

The Syrian hamster Harderian gland, a juxtaorbital organ exhibiting marked gender-associated differences in contents of porphyrins and melatonin, was used as a model system for comparing strong (in females) and moderate (in males) physiological oxidative stress. Histological differences showing much higher cell damage in females were studied in conjunction with lipid peroxidation and activities of superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase. Lipid peroxidation and enzyme activities were measured throughout the circadian cycle, revealing the importance of dynamical processes in oxidative stress. Especially in lipid peroxidation and in catalase, short-lasting rises exhibited strongest gender differences. Peaks of lipid peroxidation were about three times higher in females, compared to males. Catalase peaks of females exceeded those in males by several hundred-fold. Average levels of superoxide dismutase and glutathione peroxidase were about three or two times higher in females, respectively. A clear-cut diurnally peaking rhythm was found in glutathione peroxidase of females, which was not apparent in males. Glutathione reductase showed differences in time patterns, but less in average activities. The time courses of lipid peroxidation and of protective enzymes are not explained by circulating melatonin, whereas melatonin formed in the Harderian gland should contribute to differences in average levels. Neither damage nor antioxidative defense simply reflect the illumination cycle and are, therefore, not only a consequence of photoreactions.

Immunohistochemical detection of simian immunodeficiency virus (SIV) in rectal mucosa of experimentally infected rhesus macaques (Macaca mulatta)

Experimental simian immunodeficiency virus (SIV) infection is the most appropriate animal model for human HIV infection. Eight male rhesus monkeys (Macaca mulatta) were intravenously or intrarectally infected with SIVmac251/MPBMC to comparatively investigate the distribution and spread of the virus within the rectum during the course of the disease. SIV-positive cells were immunohistochemically detected in rectal biopsies obtained at days 3 and 7 and week 2, 4 and 12 postinfection. SIV-expressing cells were detected for the first time at one week after experimental infection and were present in the lamina propria and lymph follicles. Numbers of positive cells per individual animal varied strongly in time, with a more rapid rise in animals with rapid progression of the disease. Differences were not observed between intravenous and intrarectal infection. Our observations support the significance of the intestinal tract as target organ in initial pathogenesis of SIV infection.

Long-term follow-up study on SIV intestinal proviral load in rhesus macaques

After experimental infection with simian immunodeficiency virus (SIV), intestinal endoscopy proved to be an easily tolerated, minimal invasive procedure to obtain biopsies from the gastrointestinal tract of rhesus macaques during all stages of disease. As the GI tract is affected by many opportunistic infections and immunological impairment after SIV/human immunodeficiency virus (HIV) infection, knowledge on the proviral load is an important parameter for a better understanding of disease pathogenesis. In this paper, we describe the set-up and evaluation of a quantitative competitive polymerase chain reaction (PCR) and the quantification of SIV intestinal proviral load in a long-term follow-up study of eight rhesus monkeys (Macaca mulatta) after two different routes of virus inoculation. A SIV-specific signal could be detected as early as day 3 after infection. Of 143 biopsies from the follow-up study, 85.3% showed a positive PCR. DNA copy numbers ranged from 300 to 15,000 molecules per 100,000 cells. No significant influence of the inoculation route could be shown on either proviral load or survival time, but higher SIV proviral load was associated with a more rapid progression to disease. Therefore, the amount of proviral load in intestinal biopsies may be an important prognostic value for the further course of the disease.

Horizontal transmissible protection against myxomatosis and rabbit hemorrhagic disease by using a recombinant myxoma virus

We have developed a new strategy for immunization of wild rabbit populations against myxomatosis and rabbit hemorrhagic disease (RHD) that uses recombinant viruses based on a naturally attenuated field strain of myxoma virus (MV). The recombinant viruses expressed the RHDV major capsid protein (VP60) including a linear epitope tag from the transmissible gastroenteritis virus (TGEV) nucleoprotein. Following inoculation, the recombinant viruses induced specific antibody responses against MV, RHDV, and the TGEV tag. Immunization of wild rabbits by the subcutaneous and oral routes conferred protection against virulent RHDV and MV challenges. The recombinant viruses showed a limited horizontal transmission capacity, either by direct contact or in a flea-mediated process, promoting immunization of contact uninoculated animals.

Cloning and expression in Escherichia coli of a Fasciola hepatica gene encoding a calcium-binding protein

A Fasciola hepatica cDNA clone of 994 bp was isolated from an adult worm cDNA expression library using a rabbit serum against the excretory-secretory antigens. The nucleotide sequence of the cDNA clone revealed the presence of an open reading frame of 572 bp which encoded a 22 kDa polypeptide (Fh22) showing putative EF-hand domains. This gene was expressed in Escherichia coli and the recombinant protein used for the production of specific antibodies. Immunoblotting studies using the anti-Fh22 serum showed the presence of a polypeptide of similar molecular mass in the excretory-secretory extract of the adult parasite. The recombinant Fh22 polypeptide showed calcium-dependent electrophoretic mobility (decreased with Ca2(+)-ions and increased with EGTA). The observed behaviour of recombinant Fh22 in gel filtration experiments also suggested calcium-induced conformational changes.

Immunization with potato plants expressing VP60 protein protects against rabbit hemorrhagic disease virus

The major structural protein VP60 of rabbit hemorrhagic disease virus (RHDV) has been produced in transgenic potato plants under the control of a cauliflower mosaic virus 35S promoter or a modified 35S promoter that included two copies of a strong transcriptional enhancer. Both types of promoters allowed the production of specific mRNAs and detectable levels of recombinant VP60, which were higher for the constructs carrying the modified 35S promoter. Rabbits immunized with leaf extracts from plants carrying this modified 35S promoter showed high anti-VP60 antibody titers and were fully protected against the hemorrhagic disease.

Hypoderma lineatum: expression of enzymatically active hypodermin C in Escherichia coli and its use for the immunodiagnosis of hypodermosis

The cDNA coding for the mature hypodermin C from first instars of Hypoderma lineatum was cloned by reverse transcription and PCR amplification of total larval RNA using specific oligonucleotide primers. This cDNA was expressed in Escherichia coli as a glutathione S-transferase fusion protein. Mature hypodermin C was released from the GST-fusion after glutathione-Sepharose 4B affinity chromatography and proteolytic cleavage using factor Xa. The purified recombinant protein showed enzymatic activity in gelatin-polyacrylamide gels and when azocoll was used as substrate. An enzyme-linked immunosorbent assay was developed using the recombinant antigen. Positive/negative cutoff values were calculated using the mean OD percentage (1.74%) of 113 negative sera plus three standard deviations. Sensitivity and specificity according to the resulting cutoff (10.74%) were 85 and 98.2% respectively.

Programmed cell death in the pathogenesis of rabbit hemorrhagic disease

Rabbit hemorrhagic disease is a rapidly lethal infection caused by a calicivirus, characterized by acute liver damage and disseminated intravascular coagulation (DIC). Following morphological criteria and using a specific in situ labeling technique, we have found that liver cell death induced upon infection is due to apoptosis, and that programmed cell death is a constant feature in rabbits experimentally infected with RHDV. The process affected mainly hepatocytes, but also macrophages and endothelial cells presented morphologic hallmarks of apoptosis, expressing all these cell types viral antigens as determined by immunohistochemistry. The occurrence of programmed cell death was correlated with the appearance of the RHDV induced pathology in tissues by DNA fragmentation detection in situ. Hepatocyte apoptosis produced extensive parenchymal destruction causing a lethal, acute fulminant hepatitis that is characteristic of RHD. Apoptosis of intravascular monocytes and endothelial cell was observed together with fibrin thrombi in blood vessels. Since apoptotic cells are known sites of enhanced procoagulant activity, apoptosis of these cell populations might constitute a first step in the pathogenesis of DIC and a common pathway to other viral hemorrhagic fevers. In conclusion, apoptosis in RHD may be determinant in the development of the pathogenesis of this disease.

Expression of enzymatically active rabbit hemorrhagic disease virus RNA-dependent RNA polymerase in Escherichia coli

The rabbit hemorrhagic disease virus (RHDV) (isolate AST/89) RNA-dependent RNA-polymerase (3Dpol) coding region was expressed in Escherichia coli by using a glutathione S-transferase-based vector, which allowed milligram purification of a homogeneous enzyme with an expected molecular mass of about 58 kDa. The recombinant polypeptide exhibited rifampin- and actinomycin D-resistant, poly(A)-dependent poly(U) polymerase. The enzyme also showed RNA polymerase activity in in vitro reactions with synthetic RHDV subgenomic RNA in the presence or absence of an oligo(U) primer. Template-size products were synthesized in the oligo(U)-primed reactions, whereas in the absence of added primer, RNA products up to twice the length of the template were made. The double-length RNA products were double stranded and hybridized to both positive- and negative-sense probes.

A single dose immunization with rabbit haemorrhagic disease virus major capsid protein produced in Saccharomyces cerevisiae induces protection

The gene coding for the major capsid protein (VP60) from rabbit haemorrhagic disease virus was expressed in Saccharomyces cerevisiae under the phosphoglycerate kinase promoter. The recombinant VP60 produced in yeast was antigenically similar to the viral polypeptide as determined with a polyclonal serum. Electron microscopic observation of the recombinant yeast-derived antigen revealed the presence of virus-like particles similar in size and appearance to native capsids. Subcutaneous vaccination of rabbits with a single dose of this antigen in the absence of commercial adjuvants conferred complete protection against the haemorrhagic disease.

Processing of rabbit hemorrhagic disease virus polyprotein

Expression of rabbit hemorrhagic disease virus (RHDV) cDNAs in vitro with rabbit reticulocyte lysates and in Escherichia coli have been used to study the proteolytic processing of RHDV polyprotein encoded by ORF1. An epitope tag was used for monitoring the gene products by a specific antibody. We have identified four gene products with molecular masses of 80, 43, 73, and 60 kDa, from the amino to the carboxy terminus of the polyprotein. The amino-terminal sequences of the 43- and 73-kDa products were determined and indicated that RHDV 3C proteinase cleaved Glu-Gly peptide bonds.

Immunogenic properties of rabbit haemorrhagic disease virus structural protein VP60 expressed by a recombinant baculovirus: an efficient vaccine

We have constructed a recombinant baculovirus containing the gene encoding the structural protein VP60 from the Spanish field isolate AST/89 of rabbit haemorrhagic disease virus (RHDV). Infection of cultured Spodoptera frugiperda Sf9 cells with this recombinant virus resulted in the production of high yields of VP60 protein which did not seem to assemble to form virus like particles, but was antigenically similar to the corresponding viral protein obtained from purified virions. A VP60-dose study showed that the recombinant protein was able to elicit a protective response in rabbits against a nasal challenge with 100 LD50 of RHDV. The effective dose able to protect 50% of the animals in the absence of adjuvant was found to be 10-25 micrograms of recombinant VP60.

Androgen regulation of gene expression in the Syrian hamster Harderian gland

The androgenic control of sexual dimorphism has been studied in the Harderian gland from Syrian hamster and compared to rat Harderian gland, a system without dimorphism. Hybridization in situ with a rat cDNA clone has revealed the presence of androgen receptor mRNA in all secretory cells from male and female hamster glands. Testosterone or 5-alpha-dihydrotestosterone administration to females both caused a 60% decrease in the levels of 5-aminolevulinate synthase mRNA after 1 day of treatment, but the resulting patterns of in vitro translation using RNA from glands treated with the two androgens are different. Testosterone alters the mRNA levels for androgen receptor and 5-aminolevulinate synthase in the glands only 6 h after its implantation in females, and the action is maintained up to 10 days of treatment. Finally, androgen administration to females or deprivation in males alter androgen receptor but not 5-aminolevulinate synthase mRNA levels in rat Harderian glands. Our results suggest that the androgen receptor from Harderian glands is responsible for the sexual dimorphism found in Syrian hamsters, whereas the lack of sexual dimorphism in rat seems to be due to a restricted effect of androgens in the glands.

Molecular cloning, sequencing and expression in Escherichia coli of the capsid protein gene from rabbit haemorrhagic disease virus (Spanish isolate AST/89)

We describe the cloning, nucleotide sequencing and expression in Escherichia coli of the major capsid component (VP60) from the Spanish field isolate AST/89 of rabbit haemorrhagic disease virus (RHDV). The sequence of the 3'-terminal 2483 nucleotides of the genome was found to be 95.4% identical to the German RHDV strain, showing ten changes in the deduced VP60 amino acid sequence. The gene coding for this structural polypeptide has been expressed in bacteria as a beta-galactosidase fusion protein or using a T7 RNA polymerase-based system. The VP60 fusion protein showed only partial antigenic similarity with native VP60 and did not confer protective immunity. The recombinant VP60 produced in the T7 RNA polymerase-based system was antigenically similar to the viral polypeptide as determined using polyclonal and monoclonal antibodies. When used to immunize rabbits the recombinant VP60 was able to protect the animals against a lethal challenge using purified RHDV.

The amino terminal sequence of VP60 from rabbit hemorrhagic disease virus supports its putative subgenomic origin

Direct determination of the amino acid sequence of VP60 from rabbit hemorrhagic disease virus is impeded by the presence of a blocked N-terminus. Chemical cleavage of VP60 using cyanogen bromide allowed the identification and purification of two oligopeptides showing identical amino acid composition, one of which had its amino terminus blocked. Automated sequential degradation of the unblocked CNBr- peptide yielded the amino acid sequence EGKARTAPQGEAA. This sequence is identical to the deduced amino acid sequence following the first AUG codon found at position +10 at the 5'-end of the 2.4 kb subgenomic mRNA. These data favor the hypothesis that this viral polypeptide is mainly produced from the subgenomic mRNA and not from the genomic RNA by processing of the putative polyprotein generated from the major open reading frame.

Identification and expression of a Fasciola hepatica gene encoding a gut antigen protein bearing repetitive sequences

A Fasciola hepatica cDNA clone of about 2 kb was isolated from an expression library by immunological screening using blood serum from an experimentally infected calf. The cDNA clone hybridised to a RNA of about 3 kb in a Northern blot experiment. The nucleotide sequence of the cDNA revealed the presence of an open reading frame of 1636 bp which encoded 24 tandemly arranged 20-amino acid-long repeats, followed by 65 non-repeated residues preceding the stop codon. This antigen was expressed in Escherichia coli as beta-galactosidase fusion proteins which were used for the production of specific antibodies. Immunofluorescence studies using specific antifusion sera revealed that the antigen was specifically expressed in the parasite intestine epithelial cells. Due to its early appearance it might be possible to design diagnostic assays based on this repeated antigen for identification of recently infected animals.

In vitro translation of a subgenomic mRNA from purified virions of the Spanish field isolate AST/89 of rabbit hemorrhagic disease virus (RHDV)

Purified preparations of the Spanish field isolate of rabbit hemorrhagic disease virus AST/89 were found to contain the plus-stranded genomic RNA of more than 7.4 kilobases (kb) and large amounts of a subgenomic mRNA of 2.4 kb. The smaller RNA was translated in vitro and shown to code for a 60 kDa protein which was immunoprecipitated using anti-RHDV as well as anti-VP60 sera.