Cyprinid herpesvirus 3 Evolves In Vitro through an Assemblage of Haplotypes that Alternatively Become Dominant or Under-Represented

Viruses are able to evolve in vitro by mutations after serial passages in cell cultures, which can lead to either a loss, or an increase, of virulence. Cyprinid herpesvirus 3 (CyHV-3), a 295-kb double-stranded DNA virus, is the etiological agent of the koi herpesvirus disease (KHVD). To assess the influence of serial passages, an isolate of CyHV-3 (KHV-T) was passaged 99 times onto common carp brain (CCB) cells, and virus virulence was evaluated during passages through the experimental infections of common carp. After 78 CCB passages, the isolate was much less virulent than the original form. A comparative genomic analysis of these three forms of KHV-T (P0, P78 and P99) revealed a limited number of variations. The largest one was a deletion of 1363 bp in the predicted ORF150, which was detected in P78, but not in P99. This unexpected finding was confirmed by conventional PCR and digital PCR. The results presented here primarily suggest that, CyHV-3 evolves, at least in vitro, through an assemblage of haplotypes that alternatively become dominant or under-represented.

First record of Stegomyia albopicta (= Aedes albopictus) in Morocco: a major threat to public health in North Africa?

The Asian tiger mosquito Stegomyia albopicta (= Aedes albopictus) (Diptera: Culicidae), native to Asian forests, is a nuisance mosquito and is responsible for the transmission of arboviruses of public health importance, such as dengue, chikungunya and Zika viruses. It has colonized parts of all continents, except Antarctica, over the past 30-40 years. However, to date, the only records of S. albopicta in North Africa refer to occasional collections in 2010 and 2014 in Algeria. In early September 2015, S. albopicta larvae and adults were collected in a district of Rabat, Morocco. Morphological identification was confirmed by molecular analysis. This is the first record of this invasive mosquito in Morocco. A national surveillance programme will be implemented in 2016 to establish its geographical distribution in Morocco and to instigate control measures to prevent the establishment of new populations and the transmission of arboviruses.

Targeted genomic enrichment and sequencing of CyHV-3 from carp tissues confirms low nucleotide diversity and mixed genotype infections

Koi herpesvirus disease (KHVD) is an emerging disease that causes mass mortality in koi and common carp, Cyprinus carpio L. Its causative agent is Cyprinid herpesvirus 3 (CyHV-3), also known as koi herpesvirus (KHV). Although data on the pathogenesis of this deadly virus is relatively abundant in the literature, still little is known about its genomic diversity and about the molecular mechanisms that lead to such a high virulence. In this context, we developed a new strategy for sequencing full-length CyHV-3 genomes directly from infected fish tissues. Total genomic DNA extracted from carp gill tissue was specifically enriched with CyHV-3 sequences through hybridization to a set of nearly 2 million overlapping probes designed to cover the entire genome length, using KHV-J sequence (GenBank accession number AP008984) as reference. Applied to 7 CyHV-3 specimens from Poland and Indonesia, this targeted genomic enrichment enabled recovery of the full genomes with >99.9% reference coverage. The enrichment rate was directly correlated to the estimated number of viral copies contained in the DNA extracts used for library preparation, which varied between ∼5000 and ∼2×10⁷. The average sequencing depth was >200 for all samples, thus allowing the search for variants with high confidence. Sequence analyses highlighted a significant proportion of intra-specimen sequence heterogeneity, suggesting the presence of mixed infections in all investigated fish. They also showed that inter-specimen genetic diversity at the genome scale was very low (>99.95% of sequence identity). By enabling full genome comparisons directly from infected fish tissues, this new method will be valuable to trace outbreaks rapidly and at a reasonable cost, and in turn to understand the transmission routes of CyHV-3.

New avian paramyxoviruses type I strains identified in Africa provide new outcomes for phylogeny reconstruction and genotype classification

Newcastle disease (ND) is one of the most lethal diseases of poultry worldwide. It is caused by an avian paramyxovirus 1 that has high genomic diversity. In the framework of an international surveillance program launched in 2007, several thousand samples from domestic and wild birds in Africa were collected and analyzed. ND viruses (NDV) were detected and isolated in apparently healthy fowls and wild birds. However, two thirds of the isolates collected in this study were classified as virulent strains of NDV based on the molecular analysis of the fusion protein and experimental in vivo challenges with two representative isolates. Phylogenetic analysis based on the F and HN genes showed that isolates recovered from poultry in Mali and Ethiopia form new groups, herein proposed as genotypes XIV and sub-genotype VIf with reference to the new nomenclature described by Diel's group. In Madagascar, the circulation of NDV strains of genotype XI, originally reported elsewhere, is also confirmed. Full genome sequencing of five African isolates was generated and an extensive phylogeny reconstruction was carried out based on the nucleotide sequences. The evolutionary distances between groups and the specific amino acid signatures of each cluster allowed us to refine the genotype nomenclature.

Investigating avian influenza infection hotspots in old-world shorebirds

Heterogeneity in the transmission rates of pathogens across hosts or environments may produce disease hotspots, which are defined as specific sites, times or species associations in which the infection rate is consistently elevated. Hotspots for avian influenza virus (AIV) in wild birds are largely unstudied and poorly understood. A striking feature is the existence of a unique but consistent AIV hotspot in shorebirds (Charadriiformes) associated with a single species at a specific location and time (ruddy turnstone Arenaria interpres at Delaware Bay, USA, in May). This unique case, though a valuable reference, limits our capacity to explore and understand the general properties of AIV hotspots in shorebirds. Unfortunately, relatively few shorebirds have been sampled outside Delaware Bay and they belong to only a few shorebird families; there also has been a lack of consistent oropharyngeal sampling as a complement to cloacal sampling. In this study we looked for AIV hotspots associated with other shorebird species and/or with some of the larger congregation sites of shorebirds in the old world. We assembled and analysed a regionally extensive dataset of AIV prevalence from 69 shorebird species sampled in 25 countries across Africa and Western Eurasia. Despite this diverse and extensive coverage we did not detect any new shorebird AIV hotspots. Neither large shorebird congregation sites nor the ruddy turnstone were consistently associated with AIV hotspots. We did, however, find a low but widespread circulation of AIV in shorebirds that contrast with the absence of AIV previously reported in shorebirds in Europe. A very high AIV antibody prevalence coupled to a low infection rate was found in both first-year and adult birds of two migratory sandpiper species, suggesting the potential existence of an AIV hotspot along their migratory flyway that is yet to be discovered.

Saving resources: avian influenza surveillance using pooled swab samples and reduced reaction volumes in real-time RT-PCR

The occurrence of highly pathogenic (HP) avian influenza (AI) H5N1 in Asia and its spread to Africa and Europe prompted costly monitoring programs of wild birds and domestic poultry. AI virus excretion is tested by examining avian swab samples by real-time reverse transcription PCR (RT-qPCR). In this study, pools of swab samples and a reagents volume reduction per RT-qPCR were evaluated as measures of economization. Viral transport medium and faecal matrices were spiked with different low pathogenic AI virus strains and tested for loss of target RNA during all processing steps as individual rayon swabs or in sample pools of 5, 10 and 15 swabs. Fresh faeces from Mallard ducks and other aquatic bird species as sample matrix resulted in loss of AIV RNA of about 90% compared to transport medium. Due to sample RNA dilution in pools the likelihood of detection of single positive samples is decreasing with increasing size of sample pools. However, pools of five samples containing only one positive sample consistently gave positive results. Similarly, no differences in detection rates were obtained when analyzing 1030 wild bird swab samples either individually or in pools of five. Reducing the reaction volume of influenza A virus generic as well as of subtype-specific RT-qPCRs to 12.5 μl (2.5 μl template) instead of 25 μl did not adversely affect the limit of detection of these RT-qPCRs. A significant economic benefit without impeding detection efficacy can be achieved when sample pools of five samples are analyzed by RT-qPCR using a reduction of the reaction mix to the half of the original volume.

Avian influenza and Newcastle disease in three risk areas for H5N1 highly pathogenic avian influenza in Mali, 2007-2008

Our survey aimed to investigate avian influenza (AI) and Newcastle disease (ND) prevalence and risk factors in three areas of Mali at risk for occurrence of H5N1 highly pathogenic avian influenza. Blood samples and cloacal and oropharyngeal swabs were collected from 1470 birds between February 2007 and May 2008 and were tested by commercial enzyme-linked immunosorbent assay to detect antibodies and real-time reverse-transcription (rRT)-PCR to detect virus. Risk factors associated with seropositivity or positive rRT-PCR were identified by random effect logistic regression. AI seroprevalence was significantly lower in birds from commercial farms (0%) than in village backyard birds (3.1%). For backyard birds, no individual risk factors (species, age, sex) were identified, but birds in the Mopti area in the Sahelian zone, where millions of wild birds migrate, were more seropositive than in the Sikasso area in the Sudano-Guinean zone (odds ratio [OR] = 2.0, P = 0.051). Among backyard birds nonvaccinated against ND, ND seroprevalence was 58.4%, and the odds of seropositivity was 2.0 higher in chickens than in ducks, 1.7 higher in females than in males, 3.1 higher in adults than in young birds, and 3.0 higher in poultry from the Sikasso area than from the Mopti area (P < 0.01 in all cases). Prevalence established by rRT-PCR was low for both AI virus (1.1%) and ND virus (2.6%) and was associated with no risk factors for AI but was higher in chickens than in ducks (OR = 5.3, P = 0.05) and in the Sikasso area than in the Mopti area (OR = 3.4, P = 0.027) for ND. For AI and ND, prevalence assessed by serology or rRT-PCR varied over time, although seasonal and interannual variation could not be clearly distinguished. The intracluster correlation coefficient for serologic data was low for AI (0.014) and higher for ND (0.222). These results are useful to optimize surveillance and control strategy for notifiable avian diseases in African countries with similar agroecological and resource-limited contexts.

Understanding the ecological drivers of avian influenza virus infection in wildfowl: a continental-scale study across Africa

Despite considerable effort for surveillance of wild birds for avian influenza viruses (AIVs), empirical investigations of ecological drivers of AIV prevalence in wild birds are still scarce. Here we used a continental-scale dataset, collected in tropical wetlands of 15 African countries, to test the relative roles of a range of ecological factors on patterns of AIV prevalence in wildfowl. Seasonal and geographical variations in prevalence were positively related to the local density of the wildfowl community and to the wintering period of Eurasian migratory birds in Africa. The predominant influence of wildfowl density with no influence of climatic conditions suggests, in contrast to temperate regions, a predominant role for inter-individual transmission rather than transmission via long-lived virus persisting in the environment. Higher prevalences were found in Anas species than in non-Anas species even when we account for differences in their foraging behaviour (primarily dabbling or not) or their geographical origin (Eurasian or Afro-tropical), suggesting the existence of intrinsic differences between wildfowl taxonomic groups in receptivity to infection. Birds were found infected as often in oropharyngeal as in cloacal samples, but rarely for both types of sample concurrently, indicating that both respiratory and digestive tracts may be important for AIV replication.

Genetic data from avian influenza and avian paramyxoviruses generated by the European network of excellence (EPIZONE) between 2006 and 2011--review and recommendations for surveillance

Since 2006, the members of the molecular epidemiological working group of the European "EPIZONE" network of excellence have been generating sequence data on avian influenza and avian paramyxoviruses from both European and African sources in an attempt to more fully understand the circulation and impact of these viruses. This review presents a timely update on the epidemiological situation of these viruses based on sequence data generated during the lifetime of this project in addition to data produced by other groups during the same period. Based on this information and putting it all into a European context, recommendations for continued surveillance of these important viruses within Europe are presented.

Avian influenza virus monitoring in wintering waterbirds in Iran, 2003-2007

Background

Virological, molecular and serological studies were carried out to determine the status of infections with avian influenza viruses (AIV) in different species of wild waterbirds in Iran during 2003-2007. Samples were collected from 1146 birds representing 45 different species with the majority of samples originating from ducks, coots and shorebirds. Samples originated from 6 different provinces representative for the 15 most important wintering sites of migratory waterbirds in Iran.

Results

Overall, AIV were detected in approximately 3.4% of the samples. However, prevalence was higher (up to 8.3%) at selected locations and for certain species. No highly pathogenic avian influenza, including H5N1 was detected. A total of 35 AIVs were detected from cloacal or oropharyngeal swab samples. These positive samples originated mainly from Mallards and Common Teals.

Of 711 serum samples tested for AIV antibodies, 345 (48.5%) were positive by using a nucleoprotein-specific competitive ELISA (NP-C-ELISA). Ducks including Mallard, Common Teal, Common Pochard, Northern Shoveler and Eurasian Wigeon revealed the highest antibody prevalence ranging from 44 to 75%.

Conclusion

Results of these investigations provide important information about the prevalence of LPAIV in wild birds in Iran, especially wetlands around the Caspian Sea which represent an important wintering site for migratory water birds. Mallard and Common Teal exhibited the highest number of positives in virological and serological investigations: 43% and 26% virological positive cases and 24% and 46% serological positive reactions, respectively. These two species may play an important role in the ecology and perpetuation of influenza viruses in this region. In addition, it could be shown that both oropharyngeal and cloacal swab samples contribute to the detection of positive birds, and neither should be neglected.

Avian influenza in backyard poultry of the Mopti region, Mali

This study reports the first evidence of circulation of avian influenza viruses (AIV) in domestic poultry in Mali. In the Mopti region, where AIV have already been isolated in migratory water birds, we sampled 223 backyard domestic birds potentially in contact with wild birds and found that 3.6% had tracheal or cloacal swabs positive by real-time reverse transcription PCR (rRT-PCR) for type A influenza viruses (IVA) and that 13.7% had sera positive by commercial ELISA test detecting antibodies against IVA. None of the birds positive by rRT-PCR for IVA was positive by rRT-PCR for H5 and H7 subtypes, and none showed any clinical signs therefore indicating the circulation of low pathogenic avian influenza. Unfortunately, no virus isolation was possible. Further studies are needed to assess the temporal evolution of AIV circulation in the Mopti region and its possible correlation with the presence of wild birds.

Evidence of infection by H5N2 highly pathogenic avian influenza viruses in healthy wild waterfowl

The potential existence of a wild bird reservoir for highly pathogenic avian influenza (HPAI) has been recently questioned by the spread and the persisting circulation of H5N1 HPAI viruses, responsible for concurrent outbreaks in migratory and domestic birds over Asia, Europe, and Africa. During a large-scale surveillance programme over Eastern Europe, the Middle East, and Africa, we detected avian influenza viruses of H5N2 subtype with a highly pathogenic (HP) viral genotype in healthy birds of two wild waterfowl species sampled in Nigeria. We monitored the survival and regional movements of one of the infected birds through satellite telemetry, providing a rare evidence of a non-lethal natural infection by an HP viral genotype in wild birds. Phylogenetic analysis of the H5N2 viruses revealed close genetic relationships with H5 viruses of low pathogenicity circulating in Eurasian wild and domestic ducks. In addition, genetic analysis did not reveal known gallinaceous poultry adaptive mutations, suggesting that the emergence of HP strains could have taken place in either wild or domestic ducks or in non-gallinaceous species. The presence of coexisting but genetically distinguishable avian influenza viruses with an HP viral genotype in two cohabiting species of wild waterfowl, with evidence of non-lethal infection at least in one species and without evidence of prior extensive circulation of the virus in domestic poultry, suggest that some strains with a potential high pathogenicity for poultry could be maintained in a community of wild waterfowl.

Until recently, the highly pathogenic avian influenza (HPAI) viruses responsible for high mortality in some domestic poultry were considered not to have a wild bird reservoir, but to emerge in domestic poultry populations from low pathogenic viruses perpetuated in wild waterbirds. The rapid spread of H5N1 HPAI virus in 2005–2006, with concurrent outbreaks reported in both domestic and wild birds over Asia, Europe, and Africa, has raised concerns about the potential role of migratory birds in the epidemiology of the HPAI infection. Wild birds were sampled in Africa and tested by molecular and virological methods in an attempt to trace the circulation of HPAI viruses. In addition, some of these wild birds were equipped with satellite transmitters to track their local and migratory movements in relation to the potential spread of avian diseases. Avian influenza viruses (H5N2) were detected in wild waterfowl in Nigeria, and were subsequently characterized as highly pathogenic by molecular sequencing (HPAI viral genotype). Movements of one infected bird tracked by satellite telemetry revealed that it survived infection by an HP viral genotype. This result constitutes a rare finding of infection by an AIV with an HPAI viral genotype in healthy wild birds.

[Encephalomyocarditis virus]

Encephalomyocarditis virus (EMCV) is a cardiovirus of Picornaviridae family. It has a word wide distribution and affects a wide range of domestic and wild animal species mainly rodents, pigs and non-human primates. Depending on the virus strain and the infected host, the virus can induce myocarditis, reproductive failure, diabetes or nervous disorders. The importance of EMCV as a cause of disease in humans is unknown. However, its wide host range and its biological characteristics make this virus a potential zoonotic agent. Furthermore, several direct and indirect arguments, suggest that human infections cannot be discarded. This review summarises the current knowledge on the molecular biology, the pathogenicity and the zoonotic aspects of this virus.

Characterization of a recombinant encephalomyocarditis virus expressing the enhanced green fluorescent protein

A recombinant encephalomyocarditis virus (rEMCV2887A-egfp) expressing the enhanced green fluorescent protein (EGFP) was produced. The EGFP gene was inserted in frame within the leader protein coding sequence of a full-length cDNA clone of EMCV. RNA transcripts derived from the recombinant full-length cDNA were synthesized in vitro and transfected into BHK-21 cells. The recombinant transcript RNA remained infectious despite the insertion of EGFP as shown by cytopathic effects on BHK-21 cells and by propagation of the rescued virus. The replication kinetics in BHK-21 cells and the pathogenicity in mice of rEMCV2887A-egfp did not differ significantly from that of the parental virus. The recombinant virus was shown to produce fluorescence in infected cells after at least five passages in BHK-21 cells. However, a decrease of EGFP expression was observed following serial passages, and this was associated with the accumulation of deletion mutations within the EGFP gene. Nevertheless, using EGFP autofluorescence, infected cells were easily detected in the brain of mice infected with the first-passage recombinant virus. These data demonstrate that rEMCV2887A-egfp could be a useful tool to study virus dissemination and pathogenicity when used at low passages.

The epidemiology and diagnosis of bluetongue with particular reference to Corsica

Bluetongue (BT) and/or BT viruses (BTV) have been identified in the Mediterranean basin and the Balkans each year from 1998 to 2002 and in particular BTV serotype 2 in the French Island of Corsica (2000 and 2001). In response to these virus incursions, the French Veterinary Authorities carried out epidemiological studies that included virological, serological and entomological analysis, and two vaccination campaigns performed in the winter of 2000/2001 and the winter and spring of 2001 and 2002. Rapid and reliable serotype differentiation is essential at the start of an outbreak to allow an early selection of vaccine to control the spread of the virus. Thus, molecular tools, that complement conventional methods, have been developed for early detection of infection, determination of the serotype, and differentiation between natural infection and vaccination. Serological results showed that the first vaccination campaign during the winter of 2000/2001 did not provide full protection for all sheep and during the summer of 2001, 335 sheep flocks in Corsica were again infected by BTV 2 (7-fold more that in 2000). Entomological studies have demonstrated that the only proven vector of the disease, Culicoides imicola, was present in the island in 2000 and that it has successfully established itself in Corsica. The safety and immunogenicity of the commercial South African vaccine were studied. Fourteen sheep were vaccinated and then observed for clinical signs. Blood, sera, spleen and lymph nodes were collected and analyzed, and the results confirmed the safety and potency of using this vaccine to protect sheep from clinical disease. As a result, an intensive vaccination campaign was performed during winter and spring 2001/2002. No cases of BT had been observed by the end of summer 2002, indicating that the vaccination campaign has been successful in protecting sheep from infection.

Comparison of genome segments 2, 7 and 10 of bluetongue viruses serotype 2 for differentiation between field isolates and the vaccine strain

Bluetongue (BT) virus serotype 2 (BTV 2) was first confirmed in Tunisia in February 2000 and has since spread northward and westward, infecting several other countries and islands, including Corsica, where clinical disease was reported in October 2000. BT was again reported on the Island in July 2001, some six months after a vaccination campaign against BTV 2. The molecular relationship between isolates of the BTV 2 Corsican wild-type viruses from 2000 and 2001, and the attenuated BTV 2 vaccine were determined by comparing corresponding sequences of genome segments 2, 7 and 10 with each other and with already published sequences available in the genome database. Complete genetic stability was observed between the isolates of the Corsican BTV 2. There was some divergence between the nucleotide sequences of segment 10 obtained from the wild-type and vaccine virus strains. Based on these differences, primers were selected that could be used in RT-PCR to differentiate between the wild-type and the vaccine viruses.

Studies on the Safety and Immunogenicity of the South African Bluetongue Virus Serotype 2 Monovalent Vaccine: Specific Detection of the Vaccine Strain Genome by RT-PCR

In order to study the safety and the immunogenicity of the South African vaccine against the serotype 2 bluetongue virus, two groups of seven sheep were vaccinated with the vaccine used in the French island of Corsica. Vaccinated and non-vaccinated sheep were observed clinically and their rectal temperatures were recorded daily. The serological response in vaccinated animals confirmed the immunogenicity of the vaccine. Post-vaccinal viraemia was investigated and the vaccine genome was detected by reverse transcription polymerase chain reaction (RT-PCR). No viraemia was observed at post-vaccination days 4, 7 and 11 but the vaccine strain of virus was detected by RT-PCR throughout the experiment. The thermostability of the vaccine was also evaluated. The vaccine titre strongly decreased at temperatures higher than 35 degrees C.

Identification of bluetongue virus serotype 2 (Corsican strain) by reverse-transcriptase PCR reaction analysis of segment 2 of the genome

In October 2000, bluetongue virus was detected on the French island of Corsica. The disease was also reported in Sardinia, Calabria, Sicily and on the Spanish islands of Majorca and Minorca. This paper describes the use of molecular techniques for a rapid identification and serotype determination of serotype 2 of the virus. The nucleotide sequences of segments 2 and 7 of the genome of the Corsican strain were determined and its phylogenetic relationships are described.

Evidence of Borna disease virus genome detection in French domestic animals and in foxes (Vulpes vulpes)

Borna disease virus (BDV) is an enveloped, non-segmented negative-stranded RNA virus which belongs to the Bornaviridae family. BDV is an aetiological agent of encephalitis in horses, sheep and several other vertebrate species. In order to extend our knowledge about the presence of BDV in France, a study based on BDV RNA detection by RT-nested-PCR was done with 196 animal tissues: 171 brain samples collected from different animal species (75 horses, 59 foxes, 31 cattle, 4 dogs, 1 sheep, 1 roe deer) and 25 horse blood samples. An RNA internal standard molecule was constructed and was co-amplified with the test template. This study reports the first detection of BDV RNA in France in 10 brain samples collected from horses, foxes and cattle, and from 14 horse blood samples. Detection of the BDV genome in the brains of six red foxes is the first evidence of BDV infection in this species.

Does the short variant of the serotonin transporter linked polymorphic region constitute a marker of alcohol dependence?

The serotonin (5-hydroxytryptamine: 5-HT) system has been thought to play an important role in several steps of alcohol craving. A number of studies, including our own, have reported that alcohol dependence is associated with dysfunction of 5-HT transmission. Pharmacological and clinical studies have shown that the 5-HT transporter (5-HTT) and the 5-HT1A receptor appear to be candidate loci for the aetiology of alcohol dependence. We have analysed the presence of different 5-HTT and 5-HT1A variants in 104 alcohol-dependent patients and 38 controls for a possible association with alcohol dependence. In alcohol-dependent patients, we found a high frequency of the S allele of 5-HTTLPR (45.5% vs. 29%, chi2 = 6.33, p = 0.0081). No other significant differences were observed between the two populations for other polymorphisms. These results provide, for the first time, preliminary evidence that alcohol abuse disorders are associated with a genetic variant for 5-HT transmission. It might be possible to use this detection of the "S" allele as a clinical tool for pathology diagnosis and to advise recovering alcoholics and it could represent an aid to the prevention of relapse. Therapeutic actions could be envisaged to use this genotyping to help select the best therapeutic strategy.

Mechanism of action of acamprosate. Part I. Characterization of spermidine-sensitive acamprosate binding site in rat brain

It has been suggested that the anticraving drug, acamprosate, acts via the glutamatergic system, but the exact mechanism of action is still unknown. The aim of this study was to characterize [3H]acamprosate binding and establish whether this showed any relation to sites on the NMDA receptor complex. We found saturable specific binding of [3H]acamprosate to rat brain membranes with a KD of 120 microM and a Bmax of 450 pmol/mg of protein. This acamprosate binding site was sensitive to inhibition by spermidine (IC50: 13.32 +/- 1.1 microM; Hill coefficient = 1.04), and arcaine and glutamate both potentiated the inhibitory effect of spermidine. Acamprosate binding to the acamprosate binding site was also sensitive to inhibition by divalent cations (Ca2+, Mg2+, and Sr2+). Conversely, acamprosate displaced [14C]spermidine binding from rat brain membranes with an IC50 of 645 microM and a Hill coefficient = 1.74. This inhibitory effect of acamprosate was not affected by arcaine, and was associated with a significant reduction in Bmax and binding affinity for spermidine, suggesting an allosteric interaction between acamprosate and a spermidine binding site. These data are consistent with an effect of acamprosate on the NMDA receptor protein complex, and acamprosate was also found to alter binding of [3H]dizocilpine to rat brain membranes. When no agonists were present in vitro (minimal NMDA receptor activation), acamprosate markedly potentiated [3H]dizocilpine binding at concentrations in the 5 to 200 microM range. However, under conditions of maximal receptor activation (100 microM glutamate, 30 microM glycine), acamprosate only inhibited [3H]dizocilpine binding (at concentrations concentrations >100 microM). When these binding studies were performed in the presence of 1 microM spermidine, the enhancing effects of acamprosate on [3H]dizocilpine binding were inhibited. The results show that acamprosate binds to a specific spermidine-sensitive site that modulates the NMDA receptor in a complex way. Together, with data from al Quatari et al. (see next paper), this work suggests that acamprosate acts as "partial co-agonist" at the NMDA receptor, so that low concentrations enhance activation when receptor activity is low, whereas higher concentrations are inhibitory to high levels of receptor activation. This may be relevant to the clinical effects of acamprosate in alcohol-dependent patients during abstinence.

Experimental findings in the study of the reduction of alcohol intake

Alcohol dependence represents a major problem in public health and different animal models of dependence have been developed in rodents with the aim of studying the mechanisms of alcohol abuse. Different ways of animal alcoholisation have been established. They permit a better understanding of which neurotransmitter system is involved in the regulation of alcohol dependence. Considerable attention has been given to the role of serotonin in the control of both alcohol craving and alcohol related pathologies, i.e. anxiety, aggression or memory loss. In conclusion, the use of animal models of alcohol abuse facilitates the understanding of alcohol behavior and permits the development of new therapeutic agents.