Peak Viral Load Research Articles

Frequent Asymptomatic Respiratory Syncytial Virus Infections During an Epidemic in a Rural Kenyan Household Cohort.

Background. The characteristics, determinants, and potential contribution to transmission of asymptomatic cases of respiratory syncytial virus (RSV) infection have not been well described. Methods. A cohort of 47 households (493 individuals) in coastal Kenya was recruited and followed for a 26-week period spanning a complete RSV season. Nasopharyngeal swab specimens were requested weekly, during the first 4 weeks, and twice weekly thereafter from all household members, regardless of illness status. The samples were screened for a range of respiratory viruses by multiplex real-time polymerase chain reaction. Results. Tests on 16 928 samples yielded 205 RSV infection episodes in 179 individuals (37.1%) from 40 different households. Eighty-six episodes (42.0%) were asymptomatic. Factors independently associated with an increased risk of asymptomatic RSV infection episodes were higher age, shorter duration of infection, bigger household size, lower peak viral load, absence of concurrent RSV infections within the household, infection by RSV group B, and no prior human rhinovirus infections. The propensity of RSV spread in households was dependent on symptom status and amount (duration and load) of virus shed. Conclusions. While asymptomatic RSV was less likely to spread, the high frequency of symptomless RSV infection episodes highlights a potentially important role of asymptomatic infections in the community transmission of RSV.

Simian immunodeficiency virus infection evades vaccine-elicited antibody responses to V2 region.

An effective AIDS vaccine should elicit protective antibody responses against HIV/simian immunodeficiency virus (SIV) infection. We recently reported that mucosal priming with a replicating modified vaccinia Tiantan virus (MVTTgpe)-based vaccine regimen induces durable protection against pathogenic SIVmac239 infection in rhesus monkeys. Here, we aim to conduct a comprehensive analysis on antigenic determinants recognized by specific antibody responses generated by vaccination and SIVmac239 infection. A novel yeast surface displayed antigen library of entire SIVmac239 envelope (Env) glycoprotein was established and validated to map the major antigenic determinants (MAD) in monkey sera elicited by vaccination and infection. MAD-directed antibody responses were further analyzed for correlation of protection. The yeast surface displayed library allows the mapping of SIV-specific linear and conformational MAD. The MVTTgpe-based regimen induces antibodies targeting mainly to 6 antigenic domains covering the entire gp160. Critically, this regimen induced a uniquely predominant antibody response against a distinct MAD in variable region 2 (V2) as compared with the Ad5gpe-based vaccine and SIVmac239 infection. This MAD was associated with a higher titer of anti-V2 antibody responses, which was inversely correlated with peak and set-point viral loads. Unexpectedly, the pathogenic SIVmac239 challenge evaded the vaccine-elicited anti-V2 antibody response. Instead of recalling B-cell memory responses to the V2 MAD, viral infection directed anti-V1V2 antibodies primarily to V1 region. Moreover, the anti-V1V2 antibody responses diminished significantly in infected macaques after they enter the stage of simian AIDS. Our findings have critical implications to AIDS vaccine efforts with focus on V2 region.

Initial viral load determines the magnitude of the human CD8 T cell response to yellow fever vaccination

CD8 T cells are a potent tool for eliminating intracellular pathogens and tumor cells. Thus, eliciting robust CD8 T-cell immunity is the basis for many vaccines under development. However, the relationship between antigen load and the magnitude of the CD8 T-cell response is not well-described in a human immune response. Here we address this issue by quantifying viral load and the CD8 T-cell response in a cohort of 80 individuals immunized with the live attenuated yellow fever vaccine (YFV-17D) by sampling peripheral blood at days 0, 1, 2, 3, 5, 7, 9, 11, 14, 30, and 90. When the virus load was below a threshold (peak virus load < 225 genomes per mL, or integrated virus load < 400 genome days per mL), the magnitude of the CD8 T-cell response correlated strongly with the virus load (R(2) ∼ 0.63). As the virus load increased above this threshold, the magnitude of the CD8 T-cell responses saturated. Recent advances in CD8 T-cell-based vaccines have focused on replication-incompetent or single-cycle vectors. However, these approaches deliver relatively limited amounts of antigen after immunization. Our results highlight the requirement that T-cell-based vaccines should deliver sufficient antigen during the initial period of the immune response to elicit a large number of CD8 T cells that may be needed for protection.

The Incidence of Venous Thromboembolism (VTE) in 892 Allogeneic Hematopoietic Cell Transplant (allo-HCT) Recipients ( A single institution study comparison of VTE incidence with sirolimus versus non-sirolimus-based GVHD prophylaxis)

s / Biol Blood Marrow Transplant 21 (2015) S266eS321 S297 multivariate analysis using the LASSO approach to logistic regression analysis. Results: Of 134 allo-HSCTs, 29 (21.6%) patients experienced CMV viremia. Among these patients, median age was 51 years (range 27-67), with 48 episodes of viremia. Nine (31%) viremic patients developed CMV disease. CMV disease occurred at a median of 124 days post HSCT (range 61-322). Patients with CMV disease had a median of 2 viremic episodes before disease (range 1-4). Disease occurred at a median of 33 days from the start of the last viremic episode, and 75 days from the start of the first episode of viremia. On univariate analysis, factors associated with progression to CMV disease were: steroid-refractory acute GVHD (60 vs. 20%, p1⁄40.028); number of episodes of viremia >1x103 copies/mL (mean 2.4 vs 1.1, p1⁄40.016); longer duration of viremia (mean 38 vs. 22 days, p1⁄40.01); higher peak viral load (mean 4.49x105 vs. 8.31x103 copies/mL, p 1x103 copies/mL, a longer duration of viremia, and to have failed first-line pre-emptive ganciclovir therapy. This study, while limited, suggests that these risk factors may be predictive of CMV disease. Larger, prospective studies are needed to confirm these risk factors, some of which may be amenable to more aggressive anti-viral therapy.

Discovery of an Oral Respiratory Syncytial Virus (RSV) Fusion Inhibitor (GS-5806) and Clinical Proof of Concept in a Human RSV Challenge Study

GS-5806 is a novel, orally bioavailable RSV fusion inhibitor discovered following a lead optimization campaign on a screening hit. The oral absorption properties were optimized by converting to the pyrazolo[1,5-a]-pyrimidine heterocycle, while potency, metabolic, and physicochemical properties were optimized by introducing the para-chloro and aminopyrrolidine groups. A mean EC50 = 0.43 nM was found toward a panel of 75 RSV A and B clinical isolates and dose-dependent antiviral efficacy in the cotton rat model of RSV infection. Oral bioavailability in preclinical species ranged from 46 to 100%, with evidence of efficient penetration into lung tissue. In healthy human volunteers experimentally infected with RSV, a potent antiviral effect was observed with a mean 4.2 log10 reduction in peak viral load and a significant reduction in disease severity compared to placebo. In conclusion, a potent, once daily, oral RSV fusion inhibitor with the potential to treat RSV infection in infants and adults is reported.

Antigenic requirement for Gag in a vaccine that protects against high-dose mucosal challenge with simian immunodeficiency virus

We reported previously on a vaccine approach that conferred apparent sterilizing immunity to SIVsmE660. The vaccine regimen employed a prime–boost using vectors based on recombinant vesicular stomatitis virus (VSV) and an alphavirus replicon expressing either SIV Gag or SIV Env. In the current study, we tested the ability of vectors expressing only the SIVsmE660 Env protein to protect macaques against the same high-dose mucosal challenge. Animals developed neutralizing antibody levels comparable to or greater than seen in the previous vaccine study. When the vaccinated animals were challenged with the same high-dose of SIVsmE660, all became infected. While average peak viral loads in animals were slightly lower than those of previous controls, the viral set points were not significantly different. These data indicate that Gag, or the combination of Gag and Env are required for the generation of apparent sterilizing immunity to the SIVsmE660 challenge.

Effects of donor/recipient human leukocyte antigen mismatch on human cytomegalovirus replication following liver transplantation.

BackgroundNatural immunity against cytomegalovirus (CMV) can control virus replication after solid organ transplantation; however, it is not known which components of the adaptive immune system mediate this protection. We investigated whether this protection requires human leukocyte antigen (HLA) matching between donor and recipient by exploiting the fact that, unlike transplantation of other solid organs, liver transplantation does not require HLA matching, but some donor and recipient pairs may nevertheless be matched by chance.MethodsTo further investigate this immune control, we determined whether chance HLA matching between donor (D) and recipient (R) in liver transplants affected a range of viral replication parameters.ResultsIn total, 274 liver transplant recipients were stratified according to matches at the HLA A, HLA B, and HLA DR loci. The incidence of CMV viremia, kinetics of replication, and peak viral load were similar between the HLA matched and mismatched patients in the D+/R+ and D−/R+ transplant groups. D+/R− transplants with 1 or 2 mismatches at the HLA DR locus had a higher incidence of CMV viremia >3000 genomes/mL blood compared to patients matched at this locus (78% vs. 17%; P = 0.01). Evidence was seen that matching at the HLA A locus had a small effect on peak viral loads in D+/R− patients, with median peak loads of 3540 and 14,706 genomes/mL in the 0 and combined (1 and 2) mismatch groups, respectively (P = 0.03).ConclusionOverall, our data indicate that, in the setting of liver transplantation, prevention of CMV infection and control of CMV replication by adaptive immunity is minimally influenced by HLA matching of the donor and recipient. Our data raise questions about immune control of CMV in the liver and also about the cells in which the virus is amplified to give rise to CMV viremia.

Central Nervous System inflammation due to respiratory syncytial virus infection.

Central Nervous System inflammation due to respiratory syncytial virus infection.

Quantitative molecular viral loads in 7 horses with naturally occurring equine herpesvirus-1 infection.

Data associating quantitative viral load with severity, clinical signs and survival in equine herpesvirus-1 myeloencephalopathy (EHM) have not been reported. To report the clinical signs, treatment, and temporal progression of viral loads in 7 horses with naturally occurring EHM and to examine the association of these factors with survival. Retrospective case series. The population included 7 horses with EHM presented to the University of California, Davis William R. Pritchard Veterinary Medical Teaching Hospital from May to September 2011. Horses were graded using a neurological grading scale. Daily quantitative PCR was performed on nasal secretions and whole blood. Treatment, survival, outcome and histopathology were reported. At presentation, one horse was neurological grade 5/5, 3 were grade 4/5 and 3 were grade 3/5. All were treated with anti-inflammatory drugs, valacyclovir and management in a sling if necessary. All were infected with equine herpesvirus-1 of DNA polymerase D752 genotype. Peak viral load in nasal secretions and blood of 5 survivors ranged from 6.9 × 10(3) to 2.81 × 10(5) (median 5.11 × 10(4) ) and from 143 to 4340 gB gene copies/million eukaryotic cells (median 3146), respectively. The 2 nonsurvivors presented with grade 3/5 neurological signs and progressed to encephalopathy. Peak viral load was higher in nonsurvivors, with levels in nasal secretions of 1.9 × 10(9) and 2.2 × 10(9) and in blood of 2.05 × 10(4) and 1.02 × 10(5) gB gene copies/million eukaryotic cells. Case fatality was 2/7. Nonsurvivors had viral loads 1000-fold higher in nasal secretions and 10-fold higher in blood than survivors. There was no relationship between severity of clinical signs at presentation and survival. Thus, encephalopathy and high viral load were negatively associated with survival in this population. Further research should be performed to determine whether high viral loads are associated with encephalopathy and poor prognosis. The Summary is available in Chinese - see Supporting information.

Levofloxacin for BK virus prophylaxis following kidney transplantation: a randomized clinical trial.

BK virus infection is a significant complication of modern immunosuppression used in kidney transplantation. Viral reactivation occurs first in the urine (BK viruria) and is associated with a high risk of transplant failure. There are currently no therapies to prevent or treat BK virus infection. Quinolone antibiotics have antiviral properties against BK virus but efficacy at preventing this infection has not been shown in prospective controlled studies. To determine if levofloxacin can prevent BK viruria in kidney transplant recipients. Double-blind, placebo-controlled randomized trial involving 154 patients who received a living or deceased donor kidney-only transplant in 7 Canadian transplant centers between December 2011 and June 2013. Participants were randomly assigned to receive a 3-month course of levofloxacin (500 mg/d; n = 76) or placebo (n = 78) starting within 5 days after transplantation. The primary outcome was time to occurrence of BK viruria (detected using quantitative real-time polymerase chain reaction) within the first year after transplantation. Secondary outcomes included BK viremia, peak viral load, rejection, and patient and allograft survival. The mean follow-up time was 46.5 weeks in the levofloxacin group and 46.3 weeks in the placebo group (27 patients had follow-up terminated before the end of the planned follow-up period or development of viruria because the trial was stopped early owing to lack of funding). BK viruria occurred in 22 patients (29%) in the levofloxacin group and in 26 patients (33.3%) in the placebo group (hazard ratio, 0.91; 95% CI, 0.51-1.63; P = .58). There was no significant difference between the 2 groups in regard to any of the secondary end points. There was an increased risk of resistant infection among isolates usually sensitive to quinolones in the levofloxacin group vs placebo (14/24 [58.3%] vs 15/45 [33.3%], respectively; risk ratio, 1.75; 95% CI, 1.01-2.98) as well as a nonsignificant increased risk of suspected tendinitis (6/76 [7.9%] vs 1/78 [1.3%]; risk ratio, 6.16; 95% CI, 0.76-49.95). Among kidney transplant recipients, a 3-month course of levofloxacin initiated early following transplantation did not prevent BK viruria. Levofloxacin was associated with an increased risk of adverse events such as bacterial resistance. These findings do not support the use of levofloxacin to prevent posttransplant BK virus infection. clinicaltrials.gov Identifier: NCT01353339.

Short communication: Viremic control is independent of repeated low-dose SHIVSF162p3 exposures.

The repeat low-dose virus challenge model is commonly used in nonhuman primate studies of HIV transmission and biomedical preventions. For some viruses or challenge routes, it is uncertain whether the repeated exposure design might induce virus-directed innate or adaptive immunity that could affect infection or viremic outcomes. Retrospective cohorts of male Indian rhesus (n=40) and female pigtail (n=46) macaques enrolled in repeat low-dose rectal or vaginal SHIV(SF162p3) challenge studies, respectively, were studied to compare the relationship between the number of previous exposures and peak plasma SHIV RNA levels or viral load area under the curve (AUC), surrogate markers of viral control. Repeated mucosal exposures of 10 or 50 TCID50 of virus for rectal and vaginal exposures, respectively, were performed. Virus levels were measured by quantitative reverse-transcriptase real-time PCR. The cumulative number of SHIV(SF162p3) exposures did not correlate with observed peak virus levels or with AUC in rectally challenged rhesus macaques [peak: rho (ρ)=0.04, p=0.8; AUC: ρ=0.33, p=0.06] or vaginally challenged pigtail macaques (peak: ρ=-0.09, p=0.7; AUC: ρ=0.11, p=0.6). Infections in these models occur independently of exposure history and provide assurance that neither inoculation route nor number of exposures required for infection correlates with postinfection viremia. These data also indicate that both the vaginal and rectal repeated low-dose virus exposure models using SHIV(SF162p3) provide a reliable system for nonhuman primate studies.

Evaluation of CMV-specific cellular immune response by EliSPOT assay in kidney transplant patients

BackgroundImmunological monitoring for CMV can be useful in transplant patients; however, few centers perform it on a routine basis. ObjectivesIn this study, CMV-specific cellular response was evaluated in a population of kidney transplant recipients and related to viral infection/reactivation and other demographic and clinical features. Study designThree hundred and twenty-eight patients were studied by EliSPOT assay: 201 prospectively monitored in the first year posttransplantation, 127 with a single determination at >1 year. Clinical features, including occurrence of CMV-DNAemia, CMV serostatus, anti-viral strategies and immunosuppressive protocols, were evaluated. ResultsOverall, 66.5% of patients were CMV-responders at EliSPOT assay. No episode of infection occurred at follow-up (mean 24.5 months) in 73.4% responders versus 55.5% non-responders (p<0.005); CMV-free period was significantly longer in responders (p<0.001). Although no significant difference of peak viral load was found, prevalence of CMV-DNAemia values >105copies/mL was significantly higher in non-responders versus responders (8.2% and 2.3%, p<0.05). Non-responder status was significantly associated to CMV-seronegativity (p<0.0001), anti-viral prophylaxis use (p<0.0001), and immunosuppression induction with basiliximab (p<0.005). No significant association was found for other clinical features and immunosuppressive protocols. ConclusionsImmunological data for CMV could be used in the clinical evaluation and decision-making process, in combination with virological monitoring, in kidney transplant recipients.

Host factors determine differential disease progression after infection with nef-deleted simian immunodeficiency virus.

Infection of macaques with live attenuated simian immunodeficiency virus (SIV) usually results in long-lasting efficient protection against infection with pathogenic immunodeficiency viruses. However, attenuation by deletion of regulatory genes such as nef is not complete, leading to a high viral load and fatal disease in some animals. To characterize immunological parameters and polymorphic host factors, we studied 17 rhesus macaques infected with attenuated SIVmac239ΔNU. Eight animals were able to control viral replication, whereas the remaining animals (non-controllers) displayed variable set-point viral loads. Peak viral load at 2 weeks post-infection (p.i.) correlated significantly with set-point viral load (P<0.0001). CD4+ T-cell frequencies differed significantly soon after infection between controllers and non-controllers. Abnormal B-cell activation previously ascribed to Nef function could already be observed in non-controllers 8 weeks after infection despite the absence of Nef. Two non-controllers developed an AIDS-like disease within 102 weeks p.i. Virus from these animals transmitted to naïve animals replicated at low levels and the recipients did not develop immunodeficiency. This suggested that host factors determined differential viral load and subsequent disease course. Known Mhc class I alleles associated with disease progression in SIV WT infection only marginally influenced the viral load in Δnef-infected animals. Protection from SIVmac251 was associated with homozygosity for MHC class II in conjunction with a TLR7 polymorphism and showed a trend with initial viral replication. We speculated that host factors whose effects were usually masked by Nef were responsible for the different disease courses in individual animals upon infection with nef-deleted viruses.

A polyvalent Clade B virus-like particle HIV vaccine combined with partially protective oral preexposure prophylaxis prevents simian-human immunodeficiency virus Infection in macaques and primes for virus-amplified immunity.

Vaccination and preexposure prophylaxis (PrEP) with antiretrovirals have shown only partial protection from HIV-1 infection in human trials. Oral Truvada (emtricitabine/tenofovir disoproxil fumarate) is FDA approved as PrEP but partial adherence reduces efficacy. If combined as biomedical preventions (CBP), an HIV vaccine could protect when PrEP adherence is low and PrEP could prevent vaccine breakthroughs. The efficacy of combining oral PrEP with an HIV vaccine has not been evaluated in humans. We determined the efficacy of combining a DNA/virus-like particle (VLP) vaccine with partially effective intermittent PrEP in Indian rhesus macaques (RM). Eight RM received intramuscular inoculations of five DNA plasmids encoding four HIV-1 Clade B primary isolate Envs and SIVmac239 Gag (at weeks 0 and 4), followed by intramuscular and intranasal inoculations of homologous Gag VLPs and four Env VLPs (at weeks 12, 16, and 53). At week 61, we initiated weekly rectal exposures with heterologous SHIV162p3 (10 TCID50) along with oral Truvada (TDF, 22 mg/kg; FTC 20 mg/kg) dosing 2 h before and 22 h after each exposure. This PrEP regimen previously demonstrated 50% efficacy. Five controls (no vaccine, no PrEP) received weekly SHIV162p3. All controls were infected after a median of four exposures; the mean peak plasma viral load (VL) was 3.9×10(7) vRNA copies/ml. CBP protected seven of eight (87.5%) RM. The one infected CBP RM had a reduced peak VL of 8.8×10(5) copies/ml. SHIV exposures during PrEP amplified Gag and Env antibody titers in protected RM. These results suggest that combining oral PrEP with HIV vaccines could enhance protection against HIV-1 infection.

Cocaine alters cytokine profiles in HIV-1-infected African American individuals in the DrexelMed HIV/AIDS genetic analysis cohort.

This study evaluated the relationship between illicit drug use and HIV-1 disease severity in HIV-1-infected patients enrolled in the DREXELMED HIV/AIDS Genetic Analysis Cohort. Because cocaine is known to have immunomodulatory effects, the cytokine profiles of preferential nonusers, cocaine users, and multidrug users were analyzed to understand the effects of cocaine on cytokine modulation and HIV-1 disease severity. Patients within the cohort were assessed approximately every 6 months for HIV-1 clinical markers and for history of illicit drug, alcohol, and tobacco use. The Luminex human cytokine 30-plex panel was used for cytokine quantitation. Analysis was performed using a newly developed biostatistical model. Substance abuse was common within the cohort. Using the drug screens at the time of each visit, the subjects in the cohort were categorized as preferential nonusers, cocaine users, or multidrug users. The overall health of the nonuser population was better than that of the cocaine users, with peak and current viral loads in nonusers substantially lower than those in cocaine and multidrug users. Among the 30 cytokines investigated, differential levels were established within the 3 populations. The T-helper 2 cytokines, interleukin-4 and -10, known to play a critical role during HIV-1 infection, were positively associated with increasing cocaine use. Clinical parameters such as latest viral load, CD4 T-cell counts, and CD4:CD8 ratio were also significantly associated with cocaine use, depending on the statistical model used. Based on these assessments, cocaine use seems to be associated with more severe HIV-1 disease.

A Largely Preemptive Strategy for Prevention of Cytomegalovirus (CMV) Disease Less Practical in D+/R- Liver Transplant Recipients Receiving Anti-Thymocyte Globulin (rATG) Than D+/R+ Recipients.

Background: Our institution utilizes a hybrid method for prevention of CMV infection (CMVI) with two weeks of prophylaxis followed by preemptive therapy. We evaluated this strategy in CMV D+/R- and CMV D+/R+ liver transplant (LT). Methods: For D+/R- and D+/R+ LT recipients from 4/09-4/12, baseline and clinical data for 6 months from the date of LT were collected retrospectively. Primary outcomes were CMV viremia, symptomatic CMVI, and tissue- invasive disease (CMV-TID). Secondary outcomes included patient and allograft survival, number of CMVI, and viral load (VL). Results: We identified 191 LT recipients; 18/71 D+/R- patients (23%) developed symptomatic CMV infection vs 5/ 120 (4%) D+/R+ patients (P <0.001). 2/71 (3%) and 1/120 (1%) of D+/R- and D+/R+ patients developed CMV- TID respectively (P= 0.556). 2 deaths occurred in the D+/R- group (3%) vs 6 (5%) in D+/R+ (P= 0.712). 24/52 (46%) of D+/R- and 10/32 (31%) of D+/R+ patients with CMVI required IV therapy (P= 0.481); 24/52 (46%) and 12/32 (38%) respectively required hospitalization (P= 0.500). Median log peak VL were 3.22, 3.7, and 4.17 in D+/R- patients vs D+/R+ patients receiving no induction, basiliximab, and rATG (P= 0.016). Differences after Bonferroni correction were not statistically significant. 100% of D+/R- receiving rATG developed CMV vs 4/11 (36.4%) of D+/R+ patients. Time to CMVI differed between D+/R- and D+/R+ patients receiving rATG with infection in D+/R- patients occurring earlier (P= 0.016). The median number of CMVI in D+/R- patients receiving rATG vs basiliximab was 2 vs 1 respectively, and 0 in all others (P<0.001). Conclusion: A primarily preemptive strategy was efficacious in preventing CMV- TID. 100% of D+/R- patients receiving rATG developed CMV infection; while sample size is limited, a higher number of CMV episodes in D+/R- patients receiving rATG and significant difference in time to development of CMVI suggest that preemptive therapy may not be optimal in this subset of patients. DISCLOSURES:Yen- Lieberman, B.: Speaker's Bureau, Qiagen.

Host competence and helicase activity differences exhibited by West Nile viral variants expressing NS3-249 amino acid polymorphisms.

A single helicase amino acid substitution, NS3-T249P, has been shown to increase viremia magnitude/mortality in American crows (AMCRs) following West Nile virus (WNV) infection. Lineage/intra-lineage geographic variants exhibit consistent amino acid polymorphisms at this locus; however, the majority of WNV isolates associated with recent outbreaks reported worldwide have a proline at the NS3-249 residue. In order to evaluate the impact of NS3-249 variants on avian and mammalian virulence, multiple amino acid substitutions were engineered into a WNV infectious cDNA (NY99; NS3-249P) and the resulting viruses inoculated into AMCRs, house sparrows (HOSPs) and mice. Differential viremia profiles were observed between mutant viruses in the two bird species; however, the NS3-249P virus produced the highest mean peak viral loads in both avian models. In contrast, this avian modulating virulence determinant had no effect on LD50 or the neurovirulence phenotype in the murine model. Recombinant helicase proteins demonstrated variable helicase and ATPase activities; however, differences did not correlate with avian or murine viremia phenotypes. These in vitro and in vivo data indicate that avian-specific phenotypes are modulated by critical viral-host protein interactions involving the NS3-249 residue that directly influence transmission efficiency and therefore the magnitude of WNV epizootics in nature.

Characteristics of Epstein-Barr viraemia in adult liver transplant patients: a retrospective cohort study.

Therapeutic immunosuppression following solid organ transplantation increases the risk of Epstein-Barr (EBV) viraemia, which is implicated in post-transplant lymphoproliferative disease (PTLD). We retrospectively analysed the incidence of EBV viraemia and clinical outcomes in 98 liver transplant recipients. Patients underwent EBV DNA monitoring by whole-blood PCR: EBV levels were correlated with clinical parameters and outcomes for a median of 249days. 67% patients developed EBV viraemia (EBV DNA ≥100 copies/ml) and 30% had sustained viraemia. There was a trend towards higher hazard ratios for viraemia with exposure to aciclovir (HR 1.57, P=0.12) or in recipients of a poorly HLA-matched graft (HR 1.62, P=0.10). These associations became significant in the subgroup with >90days surveillance; HR 2.54 (P=0.0015) for aciclovir and HR 1.99 (P=0.03) for poorly matched grafts. The converse was true with ganciclovir (HR 0.56 P=0.13). Viraemia was more prolonged in men (median duration 7days vs 1; P=0.01) and in those with lower UKELD scores (11days vs 1day; P=0.001) but shortened with ganciclovir exposure (P=0.06). Younger patients were more likely to have high peak viral loads (P=0.07). No clinical signs or symptoms or adverse outcomes were associated with EBV reactivation.

CCR10 expression is required for immunogenicity of a HIV-1env DNA vaccine encoding CCL28 to enhance HIV-1env-specific IgG and IgA at relevant mucosal sites (VAC7P.986)

Abstract Development of a vaccine that drives anti-viral mucosal B cell responses is critical for protection against HIV-1 infection. It is currently unknown whether triggering CCR10/CCL28 pathways in a DNA-based vaccine results in induction of HIV-1env specific B cell immunity at mucosal sites of infection. We hypothesized that co-immunization with HIV-1env/CCL28 molecular adjuvant would augment B cell responses at gastrointestinal and vaginal sites and require CCR10. CCL28 co-immunized WT mice displayed a significant enhancement of HIV-1env specific antibody titers in serum, feces and vaginal washes, and enhanced HIV-1 specific IgA responses were abrogated in CCR10KO mice. CCL28 co-immunization did not increase the breadth of linear B cell epitopes in WT mice, but augmented the dominant epitopes elicited by antigen immunization alone. The frequency of splenic and intestinal IgA+CD19+B220+CD138+CCR10+ plasmablasts was augmented in the CCL28 co-immunized WT mice over antigen-only immunized WT controls. The physiological relevance of these findings was confirmed in a NHP model of intravaginal SIVsmE660 challenge in which CCL28 co-immunization resulted in significant increases in serum/vaginal IgG/IgA, decrease in peak viral loads, significant suppression of viral titers over 120 days, and recovery of CD4 T cells. These data support a role for CCL28 in targeting protective anti-viral B cells to mucosal sites when delivered as molecular adjuvants for HIV-1env DNA-based vaccines.

IL-17 contributes to neutrophil recruitment but not to control of viral replication during acute mouse adenovirus type 1 respiratory infection

IL-17-producing CD4+ helper T cells (Th17 cells) promote inflammatory responses to many pathogens. We used mouse adenovirus type 1 (MAV-1) to determine contributions of IL-17 to adenovirus pathogenesis. MAV-1 infection of C57BL/6 mice upregulated lung expression of IL-17 and the Th17-associated factors IL-23 and RORγt. Only CD4+T cells were associated with virus-specific IL-17 production. Fewer neutrophils were recruited to airways of IL-17−/− mice following MAV-1 infection, but there were no other differences in pulmonary inflammation between IL-17+/+ and IL-17−/− mice. Mice depleted of neutrophils using anti-Gr-1 antibody had greater lung viral loads than controls. Despite impaired neutrophil recruitment, there were no differences between IL-17+/+ and IL-17−/− mice in peak lung viral loads, clearance of virus from the lungs, or establishment of protective immunity. We demonstrate robust Th17 responses during MAV-1 respiratory infection, but these responses are not essential for control of virus infection or for virus-induced pulmonary inflammation.