CD46 Genetic Variability and HIV-1 Infection Susceptibility.

CD46 is the main receptor for complement protein C3 and plays an important role in adaptive immune responses. CD46 genetic variants are associated with susceptibility to several infectious and autoimmune diseases. Additionally, CD46 function can be subverted by HIV-1 to evade attack by complement, a strategy shared by viruses of other families. We sought to determine the association between CD46 gene variants and HIV-1 acquired through intravenous drug use (IDU) and sexual routes (n = 823). Study subjects were of European ancestry and were HIV-1 infected (n = 438) or exposed but seronegative (n = 387). Genotyping of the rs2796265 SNP located in the CD46 gene region was done by allele-specific real-time PCR. A meta-analysis merging IDU and sexual cohorts indicates that the minor genotype (CC) was associated with increased resistance to HIV-1 infection OR = 0.2, 95% CI (0.07-0.61), p = 0.004. The HIV-1-protective genotype is correlated with reduced CD46 expression and alterations in the ratio of CD46 mRNA splicing isoforms.

Diverse HCV Strains And HIV URFS Identified Amongst People Who Inject Drugs In India.

Although the prevalences of HIV and HCV are significantly higher amongst PWID in India compared to the general population, the strains circulating within this group have not been well-characterized. Through subgenomic sequencing of viruses present in residual plasma from an HIV/HCV prevalence study conducted amongst PWID across five cities in India in 2016-2017, a total of N = 498 HCV and N = 755 HIV strains were classified from N = 975 study participants. Considerable HCV diversity was identified, with different strains predominating in each region of the country. Overall, the most common strain was genotype 3a (39.0%), with genotypes 1a (26.9%), 1b (3.0%), 1c (0.2%), 3b (20.7%), 3i (2.0%), 4a (0.2%), 4d (1.0%), 6 (1.8%), 6n (4.8%), 6 v (0.2%) and one unclassifiable recombinant specimen (0.2%) also identified. The majority of the HIV specimens were subtype C (96.7%), although subtype A (0.4%), CRF01_AE (0.4%) and unique recombinant forms (URFs, 2.5%) were also detected. Notably, the geographical restriction of HIV subtype A and CRF01_AE, and HCV genotypes 4 and 6 to specific sites suggests distinct novel introductions of HIV and HCV into PWID populations, potentially via drug trafficking routes from neighboring countries where these strains are common.

Heroin delay discounting and impulsivity: Modulation by DRD1 genetic variation.

BACKGROUND: Dopamine D1 receptors (encoded by DRD1) are implicated in drug addiction and high-risk behaviors. Delay discounting (DD) procedures measure decisional balance between choosing smaller/sooner rewards vs larger/later rewards. Individuals with higher DD (rapid discounting) are prone to maladaptive behaviors that provide immediate reinforcement (eg, substance use). DRD1 variants have been linked with increased DD (in healthy volunteers) and opioid abuse. This study determined whether four dopaminergic functional variants modulated heroin DD and impulsivity. METHODS: Substance use, DD, and genotype data (DRD1 rs686 and rs5326, DRD3 rs6280, COMT rs4680) were obtained from 106 current heroin users. Subjects completed an array of DD choices during two imagined conditions: heroin satiation and withdrawal. Rewards were expressed as $10 heroin bag units, with maximum delayed amount of 30 bags. Delays progressively increased from 3 to 96 hours. RESULTS: DRD1 rs686 (A/A, n = 25; G/A, n = 56; G/G, n = 25) was linearly related to the difference in heroin DD (area under the curve; AUC) between the heroin satiation and withdrawal conditions; specifically, G/G homozygotes had a significantly smaller (satiation minus withdrawal) AUC difference score had higher drug-use impulsivity questionnaire scores, relative to A/A homozygotes, with G/A intermediate. DRD3 and COMT variants were not associated with these DD and impulsivity outcomes. CONCLUSION: DRD1 rs686 modulated the difference in heroin DD score between pharmacological states and was associated with drug-use impulsivity. These data support a role of DRD1 in opioid DD and impulsive behaviors.

Cocaine reward is reduced by decreased expression of receptor-type protein tyrosine phosphatase D (PTPRD) and by a novel PTPRD antagonist.

Receptor-type protein tyrosine phosphatase D (PTPRD) is a neuronal cell-adhesion molecule/synaptic specifier that has been implicated in addiction vulnerability and stimulant reward by human genomewide association and mouse cocaine-conditioned place-preference data. However, there have been no reports of effects of reduced expression on cocaine self-administration. There have been no reports of PTPRD targeting by any small molecule. There are no data about behavioral effects of any PTPRD ligand. We now report (i) robust effects of heterozygous PTPRD KO on cocaine self-administration (These data substantially extend prior conditioned place-preference data and add to the rationale for PTPRD as a target for addiction therapeutics.); (ii) identification of 7-butoxy illudalic acid analog (7-BIA) as a small molecule that targets PTPRD and inhibits its phosphatase with some specificity; (iii) lack of toxicity when 7-BIA is administered to mice acutely or with repeated dosing; (iv) reduced cocaine-conditioned place preference when 7-BIA is administered before conditioning sessions; and (v) reductions in well-established cocaine self-administration when 7-BIA is administered before a session (in WT, not PTPRD heterozygous KOs). These results add to support for PTPRD as a target for medications to combat cocaine use disorders. 7-BIA provides a lead compound for addiction therapeutics.

Human Endogenous Retrovirus-K HML-2 integration within RASGRF2 is associated with intravenous drug abuse and modulates transcription in a cell-line model.

HERV-K HML-2 (HK2) has been proliferating in the germ line of humans at least as recently as 250,000 years ago, with some integrations that remain polymorphic in the modern human population. One of the solitary HK2 LTR polymorphic integrations lies between exons 17 and 18 of RASGRF2, a gene that affects dopaminergic activity and is thus related to addiction. Here we show that this antisense HK2 integration (namely RASGRF2-int) is found more frequently in persons who inject drugs compared with the general population. In a Greek HIV-1-positive population (n = 202), we found RASGRF2-int 2.5 times (14 versus 6%) more frequently in patients infected through i.v. drug use compared with other transmission route controls (P = 0.03). Independently, in a United Kingdom-based hepatitis C virus-positive population (n = 184), we found RASGRF2-int 3.6 times (34 versus 9.5%) more frequently in patients infected during chronic drug abuse compared with controls (P < 0.001). We then tested whether RASGRF2-int could be mechanistically responsible for this association by modulating transcription of RASGRF2 We show that the CRISPR/Cas9-mediated insertion of HK2 in HEK293 cells in the exact RASGRF2 intronic position found in the population resulted in significant transcriptional and phenotypic changes. We also explored mechanistic features of other intronic HK2 integrations and show that HK2 LTRs can be responsible for generation of cis-natural antisense transcripts, which could interfere with the transcription of nearby genes. Our findings suggest that RASGRF2-int is a strong candidate for dopaminergic manipulation, and emphasize the importance of accurate mapping of neglected HERV polymorphisms in human genomic studies.

DNA methylation signatures of illicit drug injection and hepatitis C are associated with HIV frailty.

Intravenous illicit drug use (IDU) and hepatitis C infection (HCV) commonly co-occur among HIV-infected individuals. These co-occurring conditions may produce interacting epigenetic effects in white blood cells that influence immune function and health outcomes. Here, we report an epigenome-wide association analysis comparing IDU+/ HCV+ and IDU-/HCV- in 386 HIV-infected individuals as a discovery sample and in 412 individuals as a replication sample. We observe 6 significant CpGs in the promoters of 4 genes, NLRC5, TRIM69, CX3CR1, and BCL9, in the discovery sample and in meta-analysis. We identify 19 differentially methylated regions on chromosome 6 harboring MHC gene clusters. Importantly, a panel of IDU+/HCV+-associated CpGs discriminated HIV frailty based upon a validated index with an area under the curve of 79.3% for high frailty and 82.3% for low frailty. These findings suggest that IDU and HCV involve epigenetic programming and that their associated methylation signatures discriminate HIV pathophysiologic frailty.

Mitochondrial DNA Haplogroup A Decreases the Risk of Drug Addiction but Conversely Increases the Risk of HIV-1 Infection in Chinese Addicts.

Drug addiction is one of the most serious social problems in the world today and addicts are always at a high risk of acquiring HIV infection. Mitochondrial impairment has been reported in both drug addicts and in HIV patients undergoing treatment. In this study, we aimed to investigate whether mitochondrial DNA (mtDNA) haplogroup could affect the risk of drug addiction and HIV-1 infection in Chinese. We analyzed mtDNA sequence variations of 577 Chinese intravenous drug addicts (289 with HIV-1 infection and 288 without) and compared with 2 control populations (n = 362 and n = 850). We quantified the viral load in HIV-1-infected patients with and without haplogroup A status and investigated the potential effect of haplogroup A defining variants m.4824A > G and m.8794C > T on the cellular reactive oxygen species (ROS) levels by using an allotopic expression assay. mtDNA haplogroup A had a protective effect against drug addiction but appeared to confer an increased risk of HIV infection in addicts. HIV-1-infected addicts with haplogroup A had a trend for a higher viral load, although the mean viral load was similar between carriers of haplogroup A and those with other haplogroup. Hela cells overexpressing allele m.8794 T showed significantly decreased ROS levels as compared to cells with the allele m.8794C (P = 0.03). Our results suggested that mtDNA haplogroup A might protect against drug addiction but increase the risk of HIV-1 infection. The contradictory role of haplogroup A might be caused by an alteration in mitochondrial function due to a particular mtDNA ancestral variant.

A SDF1 genetic variant confers resistance to HIV-1 infection in intravenous drug users in China.

Despite repeated exposures to HIV-1, some individuals remain uninfected, suggesting that genetic factors confer host resistance to HIV-1 acquisition. The chemokine receptors CCR5, CXCR4 and the principal ligand SDF1 of CXCR4 play an important role for the entry of HIV-1 to target cells. To explore the relationship between genetic variants and HIV-1 infection, 11 common SNPs in CCR5, CXCR4 and SDF1 were genotyped in 921 male intravenous drug users (IDUs), of which 263 individuals were HIV-1-exposed seropositive (HESP) and 658 were HIV-1-exposed seronegative (HESN). According to the situation of syringe-sharing, the whole cohort was divided into two subgroups: syringe-sharing (SS) and syringe-not-sharing (SNS). We found that in the SNS subgroup rs17540465 of SDF1 showed significant difference of allele and genotype frequencies between HESP IDUs and HESN IDUs, but not in the SS subgroup. HESP with SNS carried significantly less allele A compared with HESN with SNS, indicating a protective role of allele A against HIV-1 infection. Syringe-sharing IDUs are supposed to be exposed highly to HIV-1 infection risk due to the direct transfer of HIV-1 infected blood to another. For syringe-not-sharing IDUs, sexual contact may be the major route of HIV-1 transmission. Considering the different route of HIV-1 transfection between two subgroups, we speculate that SDF1 may contribute susceptibility to HIV-1 infection in the route of sexual intercourse.

Influence of interleukin 10 polymorphisms -592 and -1082 to the HIV, HBV and HCV serostatus among intravenous drug users.

BACKGROUND: Interleukin 10 (IL-10) is a multifunctional cytokine produced by macrophages, monocytes, and T-helper cells. Two polymorphisms at positions -592 and -1082 have been associated with HIV susceptibility. However, their associations with susceptibility to HIV and its co-infections among intravenous drug users (IDUs) are largely unknown. METHODS: A total of 345 IDUs were recruited. Of the 173 HIV negative IDUs, 20 were classified as highly exposed HIV seronegative subjects (HESNs). A control group consisted of 496 blood donors; all HIV, HCV, and HBV negative. The IL-10-592C/A and -1082A/G were determined using TaqMan allelic discrimination assay. RESULTS: Of the IDUs, 50% were HIV positive, 89% HCV positive, 67% HBV positive and 41% had triple infection. IL-10-592C allele and -1082A allele were the most common and the -1082AG/-592CC was the most common genotype pair. All HESNs exhibited -1082A allele as compared to 81.4% of the HIV positive IDUs and 79% of donors (p=0.029 and p=0.019, respectively). None of HESNs had GG/CC genotype pair compared with 18.6% of HIV positive IDUs and 21.0% of donors (p=0.029 and p=0.019, respectively). The possession of -592AC and genotype pair AG/AC were associated with the decreased odds of HBV infection (OR=0.28; 95% CI 0.09-0.87; p=0.028 and OR=0.19; 95% CI 0.06-0.61; p=0.052, respectively). CONCLUSIONS: The presence of low producing IL-10-1082A and -592A alleles and their containing genetic variants protect highly exposed IDUs against acquisition of HIV and HBV infections.

Perceptions of genetic testing and genomic medicine among drug users.

BACKGROUND: Genetic testing will soon enter care for human immunodeficiency virus (HIV) and hepatitis C virus (HCV), and for addiction. There is a paucity of data on how to disseminate genetic testing into healthcare for marginalized populations. We explored drug users' perceptions of genetic testing. METHODS: Six focus groups were conducted with 34 drug users recruited from syringe exchange programmes and an HIV clinic between May and June 2012. Individual interviews were conducted with participants reporting previous genetic testing. RESULTS: All participants expressed acceptance of genetic testing to improve care, but most had concerns regarding confidentiality and implications for law enforcement. Most expressed more comfort with genetic testing based on individual considerations rather than testing based on race/ethnicity. Participants expressed comfort with genetic testing in medical care rather than drug treatment settings and when specifically asked permission, with peer support, and given a clear rationale. CONCLUSION: Although participants understood the potential value of genetic testing, concerns regarding breaches in confidentiality and discrimination may reduce testing willingness. Safeguards against these risks, peer support, and testing in medical settings based on individual factors and with clear rationales provided may be critical in efforts to promote acceptance of genetic testing among drug users.

Protection against hepatitis C infection via NK cells in highly-exposed uninfected injecting drug users.

BACKGROUND & AIMS: HCV seroprevalence surveys in longstanding injecting drug users (IDUs) reveal a small minority who remain seronegative, with some exhibiting HCV-specific cellular immunity. This study aimed to characterise this immunity, assess associations with risk behaviours and protection against infection. METHODS: A nested case-control series from a prospective cohort of seronegative IDUs was selected with incident cases (IN; n = 28) matched by demographics and risk behaviour to exposed uninfected (EU) subjects (n = 28). Samples were assayed for natural killer (NK) cell phenotypes and function, HCV-specific IFNγ in ELISpot, and HCV-specific CD4 T effector responses. IL28B and HLA-C/KIR2DL3 genotypes were tested. RESULTS: Numbers of activated (CD69(+)) NK cells in the mature CD56(dim)CD16(+) subset, and cytotoxic (NKp30(+)) cells in the CD56(bright)CD16(+) subset were higher in the EU subjects (p = 0.040, p = 0.038 respectively). EU subjects had higher frequencies of interferon gamma (IFNγ) producing NK cells, and lower frequencies of CD107a expression (p = 0.003, p = 0.015 respectively). By contrast, the frequency, magnitude, and breadth of HCV-specific CD4 and CD8 T cell responses did not differ, nor did IL28B, HLA-C, or KIR2DL3 allele frequencies. CONCLUSIONS: Sustained NK cell activation contributes to protection against HCV infection. HCV-specific cellular immunity is prevalent in EU subjects but does not appear to be protective.

Molecular epidemiology of hepatitis C virus genotypes and subtypes among injecting drug users in Hungary.

The aim of this study was to determine the geographical distribution of hepatitis C virus genotypes/subtypes among people who inject drugs (PWID) recruited at 22 needle exchange sites and drug outpatient services in all seven Planning and Statistical Regions of Hungary. Of 198 such PWID, 147 (74.2%), 45 (22.7%) and six (3.0%) carried genotype 1, 3 or 4, respectively, and 31 (72.1%) of the 43 genotype 1 sequences were of subtype 1a. Genotype 3 was significantly more prevalent in provincial towns than in the capital, Budapest. Injecting for a longer period and an older age both correlated with a higher prevalence of genotype 3, suggesting possible future changes in genotype distribution. The distributions of hepatitis C virus genotypes/ subtypes differed significantly between the tested PWID and the general population. The identification of genotype 3 reflected its worldwide occurrence among PWID. Our results underline the importance of genotyping before treatment, especially among people who have ever injected drugs in Hungary.

Association between TLR3 rs3775291 and resistance to HIV among highly exposed Caucasian intravenous drug users.

BACKGROUND: TLR3 recognizes dsRNA and triggers immune responses against RNA and DNA viruses. A polymorphism in TLR3, rs3775291 (Leu412Phe), has been associated with the increased susceptibility to enteroviral myocarditis, protection against tick-borne encephalitis virus and HIV-1 infection. We investigated Caucasian intravenous drug users (IDUs) and blood donors in order to evaluate the associations between TLR3 genotypes and susceptibility to HIV infection. MATERIALS AND METHODS: A total of 345 Caucasian IDUs were recruited, 50% of them were HIV positive, 89% HCV and 77% HBV positive. Based on their history of needle sharing, 20 of the HIV negative IDUs were classified as highly exposed HIV seronegatives (HESNs), 68 as non-HESNs and 85 as unexposed. The control group consisting of 497 blood donors tested negative for all three viruses. TLR3 rs3775291 were determined by using TaqMan Allelic Discrimination Assay. RESULTS: The TLR3 rs3775291 T allele frequency was similar among the HIV negative and HIV positive IDUs and blood donors - 36%, 31% and 34%, respectively. The frequency of persons possessing at least one TLR3 rs3775291 T allele was significantly higher in HESNs compared with blood donors and HIV positive IDUs (80% vs. 55%; p=0.037 and 80% vs. 53%; p=0.031, respectively). In the univariate analysis, persons who possessed at least one T allele had reduced odds of being HIV seropositive (OR=0.29, 95% CI=0.09-0.90). This association remained significant (OR=0.25, 95% CI=0.07-0.87) after the adjustment for other co-variates (HCV, HBV serostatus and duration of intravenous drug use). CONCLUSIONS: The TLR3 rs3775291 T allele has a protective effect against HIV infection among HESNs IDUs.

CCR5 haplotypes influence HCV serostatus in Caucasian intravenous drug users.

BACKGROUND: Up to 90% HIV-1 positive intravenous drug users (IDUs) are co-infected with HCV. Although best recognized for its function as a major co-receptor for cell entry of HIV, CC chemokine receptor 5 (CCR5) has also been implicated in the pathogenesis of HCV infection. Here, we investigated whether CCR5 haplotypes influence HIV-1 and HCV seropositivity among 373 Caucasian IDUs from Estonia. METHODS: Of these IDUs, 56% and 44% were HIV and HCV seropositive, respectively, and 47% were coinfected. 500 blood donors seronegative for HIV and HCV were also evaluated. CCR5 haplotypes (HHA to HHG*2) were derived after genotyping nine CCR2-CCR5 polymorphisms. The association between CCR5 haplotypes with HIV and/or HCV seropositivity was determined using logistic regression analysis. Co-variates included in the models were length of intravenous drug use, HBV serostatus and copy number of CCL3L1, the gene encoding the most potent HIV-suppressive chemokine and ligand for CCR5. RESULTS: Compared to IDUs seronegative for both HCV and HIV (HCV-/HIV-), IDUs who were HCV+/HIV- and HCV+/HIV+were 92% and 82%, respectively, less likely to possess the CCR5-HHG*1 haplotype, after controlling for co-variates (P(adjusted) = 1.89 × 10(-4) and 0.003, respectively). This association was mostly due to subjects bearing the CCR5 HHE and HHG*1 haplotype pairs. Approximately 25% and<10% of HCV-/HIV- IDUs and HCV-/HIV- blood donors, respectively, possessed the HHE/HHG*1 genotype. CONCLUSIONS: Our findings suggest that HHG*1-bearing CCR5 genotypes influence HCV seropositivity in a group of Caucasian IDUs.

HCV 6a prevalence in Guangdong province had the origin from Vietnam and recent dissemination to other regions of China: phylogeographic analyses.

BACKGROUND: Recently in China, HCV 6a infection has shown a fast increase among patients and blood donors, possibly due to IDU linked transmission. METHODOLOGY/FINDINGS: We recruited 210 drug users in Shanwei city, Guangdong province. Among them, HCV RNA was detected in 150 (71.4%), both E1 and NS5B genes were sequenced in 136, and 6a genotyped in 70. Of the 6a sequences, most were grouped into three clusters while 23% represent emerging strains. For coalescent analysis, additional 6a sequences were determined among 21 blood donors from Vietnam, 22 donors from 12 provinces of China, and 36 IDUs from Liuzhou City in Guangxi Province. Phylogeographic analyses indicated that Vietnam could be the origin of 6a in China. The Guangxi Province, which borders Vietnam, could be the first region to accept 6a for circulation. Migration from Yunnan, which also borders Vietnam, might be equally important, but it was only detected among IDUs in limited regions. From Guangxi, 6a could have further spread to Guangdong, Yunnan, Hainan, and Hubei provinces. However, evidence showed that only in Guangdong has 6a become a local epidemic, making Guangdong the second source region to disseminate 6a to the other 12 provinces. With a rate of 2.737×10⁻³ (95% CI: 1.792×10⁻³ to 3.745×10⁻³), a Bayesian Skyline Plot was portrayed. It revealed an exponential 6a growth during 1994-1998, while before and after 1994-1998 slow 6a growths were maintained. Concurrently, 1994-1998 corresponded to a period when contaminated blood transfusion was common, which caused many people being infected with HIV and HCV, until the Chinese government outlawed the use of paid blood donations in 1998. CONCLUSIONS/SIGNIFICANCE: With an origin from Vietnam, 6a has become a local epidemic in Guangdong Province, where an increasing prevalence has subsequently led to 6a spread to many other regions of China.

Alpha-synuclein and heroin craving in opiate-dependent patients on injectable heroin maintenance.

Research suggests that alpha-synuclein (SNCA) and NACP-Rep1, a polymorphic complex microsatellite repeat ~10 kb upstream of the SNCA gene translational start, may be involved in substance-use behaviors and craving. This study was the first to examine the effects of diacetylmorphine (DAM) on peripheral SNCA protein expression along with craving in opiate-dependent patients and to compare their NACP-Rep1 allele lengths with those of healthy controls. Using an experimental design, opiate-dependent patients on injectable heroin maintenance were investigated at four time points, twice pre- and post-injection of DAM. SNCA protein levels of 30 DAM-maintained patients were measured using enzyme-linked immunosorbent assay. Participant-rated effects were assessed in 42 patients by Tiffany's Heroin Craving Questionnaire (HCQ), Gossop's Short Opiate Withdrawal Scale and Visual Analogs. NACP-Rep1 alleles of 42 patients and 101 controls were analyzed. One-way repeated-measures ANOVAs provided significant overall effects for SNCA protein content (P = 0.028), craving (P < 0.001), withdrawal symptomatology (P < 0.001) and mood (P < 0.001), indicating that DAM injections may not only reduce craving but also SNCA protein expression. However, there was no association between protein expression and craving. Relative to controls, patients had significantly longer NACP-Rep1 alleles (P < 0.001). NACP-Rep1 allele lengths correlated positively with HCQ total scores averaged across all time points (r = 0.420; P = 0.006) as well as with post-DAM HCQ total scores in the morning (r = 0.488, P = 0.001) and afternoon (r = 0.423, P = 0.005). The findings provide evidence of a contributory role of SNCA and NACP-Rep1 for opiate dependence.

The effects of widespread methadone treatment on the molecular epidemiology of hepatitis C virus infection among injection drug users in Hong Kong.

The distribution of HCV genotypes among injection drug users in Hong Kong was assessed in context of methadone treatment availability. Three time periods were defined by the year of initiating injection-on or before 1980, 1981-1994, and 1995-2006-with methadone becoming widely available since the second period. Of the 273 HCV RNA-positive cases, the most prevalent subtype was HCV 6a (52.4%), followed by HCV 1b (38.5%). The new variants of HCV subtypes 6e and 6h were detected. Both subtypes 1b and 6a were prevalent among older injectors, while subtype 3a was more common in young injectors and those initiating injection recently during the third time period. Age (P < 0.05) and recent injection frequency (P < 0.01) were independently associated with HCV 6a infection. Subtype 1b was predominant in the first period, whereas 6a was more common in the second and third. Subtype 1b sequences appeared to have originated at two positions on the phylogenetic tree, while 6a showed a more disperse distribution suggestive of multiple introductions. Phylogenetic analysis on the NS5B region did not reveal specific clustering of any subtype/genotype. Overall, there was no suggestion of outbreaks of HCV. The extensive use of methadone may have protected Hong Kong from the emergence of HCV clusters among injection drug users.

A decrease in gamma-synuclein expression within the nucleus accumbens increases cocaine intravenous self-administration in the rat.

Except as a marker of cancer progression, gamma-synuclein (GSyn) had received little attention. Recent data showed however that GSyn modulates cocaine-induced locomotor effects, suggesting that it could also play a role in cocaine reinforcing effects. In the rat, siRNAs targeting GSyn expression were injected in the nucleus accumbens and cocaine reinforcing effects were evaluated by means of intravenous self-administration. A dose-response curve was followed by procedures of progressive ratio, extinction, cocaine- and cue-induced reinstatements. Decrease of GSyn expression increased self-administration over a large range of doses. This effect was associated with an increase in cocaine-induced reinstatement. The present data reveal that GSyn exert a specific negative control on cocaine-induced reinforcing and incentive effects.

Protective KIR-HLA interactions for HCV infection in intravenous drug users.

Intravenous drug use has become the principal route of hepatitis C virus (HCV) transmission due to the sharing of infected needles. In this study, we analyzed the distribution of HLA-KIR genotypes among 160 Puerto Rican intravenous drug users (IDUs) with HCV infection and 92 HCV-negative Puerto Rican IDUs. We found a significant association between the presence of different combinations of KIR inhibitory receptor genes (KIR2DL2 and/or KIR2DL3, pC=0.01, OR=0.07; KIR2DL2 and/or KIR2DL3+KIR2DS4, pC=0.01, OR=0.39) and HLA-C1 homozygous genotypes (HLA-C1+KIR2DS4, pC=0.02, OR=0.43; HLA-C1+KIR2DL2+KIR2DS4, pC=0.02, OR=0.40) together with the activating receptor KIR2DS4 (HLA-C1+KIR2DS4+KIR2DL3 and/or KIR2DL2, pC=0.004, OR=0.38) with protection from HCV infection. Our findings in HCV-infected and non-infected IDUs suggest an important role for KIRs (KIR2DL2 and KIR2DL3) with group HLA-C1 molecules, in the presence of activating KIR2DS4, in protection from HCV infection. These results support the hypothesis that activator signaling, mediated by KIR2DS4, plays a determinant role in the regulation of NK cell antiviral-activity.

Selective breeding for intravenous drug self-administration in rats: a pilot study.

Although the role of genetic factors in the response to drugs of abuse has been emphasized, no earlier studies have applied selective breeding to intravenous drug self-administration. Here we report the effects of six generations of selective breeding for rat lines with low or high levels of intravenous drug self-administration (LS and HS lines, respectively). Rats from the outbred founder population and the first selected generation were evaluated for intravenous self-administration of either morphine or cocaine. All subsequent generations were assessed for self-administration of cocaine, using a multifactorial score based on how rapidly self-administration behavior was acquired, levels of self-administration during acquisition, and the response to different doses of cocaine. All changes in cocaine self-administration that occurred in generations three through six were consistent with effects of selection, with most measures differing in sixth-generation LS and HS animals. Sixth-generation HS rats self-administered approximately five times more injections of low-dose cocaine than LS animals under fixed-ratio-5 (a schedule in which an injection is delivered after five lever presses). These findings support a role of genetic factors in influencing cocaine-reinforced behavior. Establishment of the LS and HS lines will allow future studies to evaluate the role of specific genetic factors that underlie these differences and may contribute to substance abuse disorders in humans.