CMV specific T cell immune response in hepatitis C negative kidney transplant recipients receiving transplant from hepatitis C viremic donors and hepatitis C aviremic donors

Kidney transplants (KT) from hepatitis C (HCV) viremic donors to HCV negative recipients has shown promising renal outcomes, however, high incidence of cytomegalovirus (CMV) viremia were reported. We performed a prospective cohort study of 52 HCV negative KT recipients from Methodist University Hospital including 41 receiving transplants from HCV aviremic donors and 11 from HCV viremic donors. CMV specific CD4+ and CD8 + T cell immunity was measured by intracellular flow cytometry assay. Primary outcome was the development of positive CMV specific CD4+ and CD8 + T cell immune response in the entire cohort and each subgroup. The association between donor HCV status and CMV specific CD4+ and CD8 + T cell immune response was analyzed by Cox proportional hazard models. Mean recipient age was 48 ± 13 years, with 73% male and 82% African American. Positive CMV specific CD4+ and CD8 + T cell immune response was found in 53% and 47% of the cohort at 1 month, 65% and 70% at 2 months, 80% and 75% at 4 months, 89% and 87% at 6 months, and 94% and 94% at 9 months post-transplant, respectively. There was no significant difference in the incidence of positive CMV specific T cell immune response between recipients of transplants from HCV aviremic donors compared to HCV viremic donors in unadjusted (for CD8+: HR = 1.169, 95%CI: 0.521-2.623; for CD4+: HR = 1.208, 95%CI: 0.543-2.689) and adjusted (for CD8+: HR = 1.072, 95%CI: 0.458-2.507; for CD4+: HR = 1.210, 95%CI: 0.526-2.784) Cox regression analyses. HCV viremia in donors was not associated with impaired development of CMV specific T cell immunity in this cohort.

How modular protein nanoparticles may expand the ability of subunit anti-viral vaccines: The spring viremia carp virus (SVCV) case

Spring viremia of carp (SVC) remains as a vaccine orphan disease mostly affecting juvenile specimens. Young fish are especially difficult to vaccinate and oral administration of vaccine combined with food would be the election system to minimise stress and the vaccination costs associated to injection. However, administration of prophylactics with food pellets faces off several drawbacks mainly related with vaccine degradation and weak protection correlates of oral vaccines. Here we present a platform based on recombinant proteins (subunit vaccines) manufactured as highly resistant nanostructured materials, and providing excellent levels of protection against SVC virus in a preliminary i.p injection challenge. The G3 domain of SVCV glycoprotein G was overexpressed in E. coli together with IFNγ and the modular protein was purified from bacterial aggregates (inclusion bodies) as highly organised nanostructured biomaterial (nanopellets, NP). These SVCV-IFN^NP were taken up by zebrafish cells leading to the enhanced expression of different antiviral and IFN markers (e.g vig1, mx, lmp2 or ifngr1 among others) in zebrafish liver cells (ZFL). To monitor if SVCV^NP and SVCV-IFN^NP can be taken up by intestinal epithelia and can induce antiviral response we performed experiments with SVCV^NP and SVCV-IFN^NP in 3 days post fertilization (dpf) zebrafish larvae. Both, SVCV^NP and SVCV-IFN^NP were taken up and accumulated in the intestine without signs of toxicity. The antiviral response in larvae showed a different induction pattern: SVCV-IFN^NP did not induce an antiviral response while SVCV^NP showed a good antiviral induction. Interestingly ZF4, an embryonic derived cell line, showed an antiviral response like ZFL cells, although the lmp2 and ifngr1 (markers of the IFNγ response) were not overexpressed. Experiments with adult zebrafish indicated an excellent level of protection against a SVCV model infection where SVCV-IFN^NP vaccinated fish reached 20% cumulative mortality while control fish reached over 80% cumulative mortality.

Disruption of the HLA-E/NKG2X axis is associated with uncontrolled HIV infections

The contribution of the HLA-E/NKG2X axis in NK-mediated control of HIV infection remains unclear. We have studied the relationship between HLA-E expression and phenotypical as well as functional characteristics of NK cells, in the context of chronic HIV infection and in an in vitro model of acute infection. High viremia in HIV+ individuals was related to increased HLA-E expression, and changes in NK subpopulations, especially a reduction of the CD56bright as well as an increase in adaptive NK subpopulation. Uncontrolled HIV infection was also characterized by a reversion of the NKG2A/NKG2C expression ratio and a loss of positive and negative regulation of NK mediated by HLA-E. This was reflected in a lower cytotoxic, degranulation and cytokine production capacity, especially in CD56bright and adaptive NK. In line with these results, HLA-E expression showed a positive correlation with viral growth inhibition in an in vitro model of acute infection at day 7, which was lost after 14 days of culture. Using HLA-E expressing K562 cells, we determined that only one out of 11 described HIV-derived HLA-E epitopes increased HLA-E surface stability. In spite of that, eight of the 11 epitopes were capable of increasing degranulation and three drove differences in NK-cell mediated cell lysis or cytokine secretion. In conclusion, our results indicate that HLA-E molecules presenting HIV-derived epitopes may sensitize target cells for NK lysis in early HIV infection. However, prolonged exposure to elevated HLA-E expression levels in vivo may lead to NK cell dysfunction and reduced viral control In chronic infection.

Lower dose of ATG combined with basiliximab for haploidentical hematopoietic stem cell transplantation is associated with effective control of GVHD and less CMV viremia

Currently, the graft-versus-host disease (GVHD) prophylaxis consists of an immunosuppressive therapy mainly based on antithymocyte globulin (ATG) or post-transplant cyclophosphamide (PTCy). GVHD remains a major complication and limitation to successful allogeneic haploidentical hematopoietic stem cell transplantation (haplo-HSCT). We modified the ATG-based GVHD prophylaxis with the addition of basiliximab in the setting of haplo-HSCT and attempted to explore the appropriate dosages. We conducted a retrospective analysis of 239 patients with intermediate- or high-risk hematologic malignancies who received haplo-HSCT with unmanipulated peripheral blood stem cells combined or not with bone marrow. All patients received the same GVHD prophylaxis consisting of the combination of methotrexate, cyclosporine or tacrolimus, mycofenolate-mofetil, and basiliximab with different doses of ATG (5-9mg/kg). With a median time of 11 days (range, 7-40 days), the rate of neutrophil engraftment was 96.65%. The 100-day cumulative incidences (CIs) of grade II-IV and III-IV aGVHD were 15.8 ± 2.5% and 5.0 ± 1.5%, while the 2-year CIs of total cGVHD and extensive cGVHD were 9.8 ± 2.2% and 4.1 ± 1.5%, respectively. The 3-year CIs of treatment-related mortality (TRM), relapse, overall survival (OS), and disease-free survival (DFS) were 14.6 ± 2.6%, 28.1 ± 3.4%, 60.9 ± 3.4%, 57.3 ± 3.4%, respectively. Furthermore, the impact of the reduction of the ATG dose to 6 mg/kg or less in combination with basiliximab on GVHD prevention and transplant outcomes among patients was analyzed. Compared to higher dose of ATG(>6mg/kg), lower dose of ATG (≤6mg/kg) was associated with a significant reduced risk of CMV viremia (52.38% vs 79.35%, P<0.001), while the incidences of aGVHD and cGVHD were similar between the two dose levels. No significant effect was found with regard to the risk of relapse, TRM, and OS. ATG combined with basiliximab could prevent GVHD efficiently and safely. The optimal scheme of using this combined regimen of ATG and basiliximab is that administration of lower dose ATG (≤6mg/kg), which seems to be more appropriate for balancing infection control and GVHD prophylaxis.

Repeated Intravaginal Inoculation of Zika Virus Protects Cynomolgus Monkeys from Subcutaneous Superchallenge

Zika virus (ZIKV) outbreaks in Central and South America caused severe public health problems in 2015 and 2016. These outbreaks were finally contained through several methods, including mosquito control using insecticides and repellents. Additionally, the development of herd immunity in these countries might have contributed to containing the epidemic. While ZIKV is mainly transmitted by mosquito bites and mucosal transmission via bodily fluids, including the semen of infected individuals, has also been reported. We evaluated the effect of mucosal ZIKV infection on continuous subcutaneous challenges in a cynomolgus monkey model. Repeated intravaginal inoculations of ZIKV did not induce detectable viremia or clinical symptoms, and all animals developed a potent neutralizing antibody, protecting animals from the subsequent subcutaneous superchallenge. These results suggest that viral replication at mucosal sites can induce protective immunity without causing systemic viremia or symptoms.

The effect and underlying mechanism of yeast β-glucan on antiviral resistance of zebrafish against spring viremia of carp virus infection

β-glucan has been used as immunostimulant for fish. However, the effect of yeast β-glucan on viral infections has been less studied in fish. In this study, we investigated the effects of β-glucan on the resistance of zebrafish against spring viraemia of carp virus (SVCV) and elucidated the underlying mechanisms. Zebrafish were fed with a control diet or diet supplemented with 0.01% and 0.025% β-glucan for 2 weeks, and were challenged by SVCV. Zebrafish embryonic fibroblast (ZF4) cells were treated with 5 μg/mL β-glucan and were infected by SVCV. We further investigated the effect of β-glucan on autophagy level post SVCV infection. The intestinal microbiota was evaluated by 16S rRNA gene pyrosequencing. Results showed that dietary supplementation of 0.025% β-glucan significantly increased survival rate of zebrafish compared with control group after SVCV challenge (P < 0.05). Dietary β-glucan significantly increased the expression of genes related to type I IFN antiviral immune pathway in the spleen of zebrafish after viral infection, including type I IFN genes (ifnφ1, ifnφ2, ifnφ3), IFN-stimulated genes (mxb, mxc), as well as other genes involved in the IFN signaling pathway, including tlr7, rig1, mavs, irf3 and irf7. Morpholino knockdown of type I IFN receptors dampened the antiviral effect of β-glucan in zebrafish larvae, indicating that β-glucan-mediated antiviral function was at least partially dependent on IFN immune response. Furthermore, β-glucan can inhibit the replication of SVCV in ZF4 cells. However, β-glucan did not stimulate type I IFN antiviral response in ZF4 cells, and the antiviral effect of β-glucan in ZF4 was independent of Myd88. Interestingly, β-glucan induced autophagy in ZF4 cells after SVCV infection. Inhibition of autophagy blocked the antiviral effect of β-glucan in ZF4 cells. Lastly, dietary β-glucan changed the composition of intestinal microbiota in zebrafish, with reduced abundance of Proteobacteria and an enrichment of Fusobacteria and Firmicutes. To sum up, our results indicate that the β-glucan enhanced resistance of zebrafish against SVCV and the mechanism involved stimulation of type I IFN antiviral immune response of fish after viral infection.

Cytomegalovirus Viremia Predicts Postdischarge Mortality in Kenyan HIV-Exposed Uninfected Children

BACKGROUND

Cytomegalovirus (CMV) viremia is associated with mortality in severely ill immunocompetent adults and hospitalized children with HIV (CWH). We measured CMV viremia in HIV-exposed and -unexposed Kenyan children aged 1-59 months discharged from hospital and determined its relationship with postdischarge mortality.

METHODS

CMV DNA levels were measured in plasma from 1024 children (97 of which were HIV exposed uninfected [HEU], and 15 CWH). Poisson and Cox proportional hazards regression models were used to identify correlates of CMV viremia ≥ 1000 IU/mL 
and estimate associations with 6-month mortality, respectively.

RESULTS

CMV viremia was detected in 31% of children, with levels ≥ 1000 IU/mL in 5.8%. HIV infection, age < 2 years, breastfeeding, and midupper arm circumference < 12.5 cm were associated with CMV viremia ≥ 1000 IU/mL. Among HEU children, CMV ≥ 1000 IU/mL (hazard ratio [HR] = 32.0; 95% confidence interval [CI], 2.9-354.0; P = .005) and each 1-log increase in CMV viral load (HR = 5.04; 95% CI, 1.7-14.6; P = .003) were associated with increased risk of mortality. CMV viremia was not significantly associated with mortality in HIV-unexposed children.

CONCLUSIONS

CMV levels at hospital postdischarge predict increased risk of 6-month mortality in Kenyan HEU children. CMV suppression may be a novel target to reduce mortality in HEU children.

CLINICAL TRIAL REGISTRATION

NCT02414399.

Dose-Dependent Hepacivirus Infection Reveals Linkage between Infectious Dose and Immune Response

More than 70 million people worldwide are still infected with the hepatitis C virus 30 years after its discovery, underscoring the need for a vaccine. To develop an effective prophylactic vaccine, detailed knowledge of the correlates of protection and an immunocompetent surrogate model are needed. In this study, we describe the minimum dose required for robust equine hepacivirus (EqHV) infection in equids and examined how this relates to duration of infection, seroconversion, and transcriptomic responses. To investigate mechanisms of hepaciviral persistence, immune response, and immune-mediated pathology, we inoculated eight EqHV naive horses with doses ranging from 1-2 copies to 1.3 × 106 RNA copies per inoculation. We characterized infection kinetics, pathology, and transcriptomic responses via next generation sequencing. The minimal infectious dose of EqHV in horses was estimated at 13 RNA copies, whereas 6 to 7 copies were insufficient to cause infection. Peak viremia did not correlate with infectious dose, while seroconversion and duration of infection appeared to be affected. Notably, seroconversion was undetectable in the low-dose infections within the surveillance period (40 to 50 days). In addition, transcriptomic analysis revealed a nearly dose-dependent effect, with greater immune activation and inflammatory response observed in high-dose infections than in low-dose infections. Interestingly, inoculation with 6-7 copies of RNA that did not result in productive infection, but was associated with a strong immune response, similar to that observed in the high-dose infections. IMPORTANCE We demonstrate that the EqHV dose of infection plays an important role for inducing immune responses, possibly linked to early clearance in high-dose and prolonged viremia in low-dose infections. In particular, pathways associated with innate and adaptive immune responses, as well as inflammatory responses, were more strongly upregulated in high-dose infections than in lower doses. Hence, inoculation with low doses may enable EqHV to evade strong immune responses in the early phase and therefore promote robust, long-lasting infection.

Virological suppression among gay, bisexual, and other men who have sex with men living with HIV in Vancouver, Canada: A longitudinal cohort study from 2012-2017

INTRODUCTION

In 2010, British Columbia (BC) implemented HIV Treatment as Prevention (TasP) as policy. We examined trends in virologic suppression and determinants of significant viremia among a prospective biobehavioural cohort of men who have sex with men (gbMSM) in Vancouver from 2012-2017.

METHODS

Respondent-driven sampling was used to recruit sexually active gbMSM (≥16 years) who completed biannual study visits with a computer-assisted self-interview and clinical CD4 and viral load (VL) testing. We linked participant data with the BC HIV Drug Treatment Program to obtain antiretroviral dispensing and VL data. We conducted a trend analysis of VL suppression using univariable generalized estimating equation (GEE) multi-level modelling and multivariable GEE to identify factors associated with episodes of VL ≥200 copies/mL.

RESULTS

Of 774 participants, 223 were living with HIV at baseline and 16 were diagnosed during follow-up (n = 239). We observed a significant trend towards reduced levels of unsuppressed VL (>200 copies/mL) from 22% (07/2012-12/2012) to 12% (07/2016-12/2016) (OR:0.87; 95%CI:0.83-0.91 for each 6-month period). Among those with at least one follow-up visit, (n = 178, median follow-up = 3.2 years, median age = 46.9 years), younger age (aOR:0.97; 95%CI:0.94-0.99, per year), ecstasy use (aOR:1.69; 95%CI:1.13-2.53), crystal methamphetamine use (aOR:1.71; 95%CI:1.18-2.48), seeking sex via websites (aOR:1.46; 95%CI:1.01-2.12), and lower HIV treatment optimism (aOR:0.94; 95%CI:0.90-0.97) were associated with episodes of elevated viremia.

CONCLUSIONS

During a period when TasP policy was actively promoted, we observed a significant trend towards reduced levels of unsuppressed VL. Continued efforts should promote HIV treatment optimism and engagement, especially among younger gbMSM and those who use ecstasy and crystal methamphetamine.

Intraocular human cytomegaloviruses of ocular diseases are distinct from those of viremia and are capable of escaping from innate and adaptive immunity by exploiting HLA-E-mediated peripheral and central tolerance

Human cytomegalovirus (HCMV) infections develop into CMV diseases that result in various forms of manifestations in local organs. CMV-retinitis is a form of CMV disease that develops in immunocompromised hosts with CMV-viremia after viruses in the peripheral circulation have entered the eye. In the HCMV genome, extensive diversification of the UL40 gene has produced peptide sequences that modulate NK cell effector functions when loaded onto HLA-E and are subsequently recognized by the NKG2A and NKG2C receptors. Notably, some HCMV strains carry UL40 genes that encode peptide sequences identical to the signal peptide sequences of specific HLA-A and HLA-C allotypes, which enables these CMV strains to escape HLA-E-restricted CD8+T cell responses. Variations in UL40 sequences have been studied mainly in the peripheral blood of CMV-viremia cases. In this study, we sought to investigate how ocular CMV disease develops from CMV infections. CMV gene sequences were compared between the intraocular fluids and peripheral blood of 77 clinical cases. UL40 signal peptide sequences were more diverse, and multiple sequences were typically present in CMV-viremia blood compared to intraocular fluid. Significantly stronger NK cell suppression was induced by UL40-derived peptides from intraocular HCMV compared to those identified only in peripheral blood. HCMV present in intraocular fluids were limited to those carrying a UL40 peptide sequence corresponding to the leader peptide sequence of the host's HLA class I, while UL40-derived peptides from HCMV found only in the peripheral blood were disparate from any HLA class I allotype. Overall, our analyses of CMV-retinitis inferred that specific HCMV strains with UL40 signal sequences matching the host's HLA signal peptide sequences were those that crossed the blood-ocular barrier to enter the intraocular space. UL40 peptide repertoires were the same in the intraocular fluids of all ocular CMV diseases, regardless of host immune status, implying that virus type is likely to be a common determinant in ocular CMV disease development. We thus propose a mechanism for ocular CMV disease development, in which particular HCMV types in the blood exploit peripheral and central HLA-E-mediated tolerance mechanisms and, thus, escape the antivirus responses of both innate and adaptive immunity.

Transcriptome analysis identifies LGP2 as an MDA5-mediated signaling activator following spring viremia of carp virus infection in common carp (Cyprinus carpio L.)

The common carp (Cyprinus carpio L.) is an important farmed species worldwide. Mucosal-associated lymphoid tissues play an essential role in the fight against pathogen infection. Spring viremia of carp virus (SVCV) poses a serious threat to the common carp aquaculture industry. Understanding the molecular mechanisms driving mucosal immune responses to SVCV infection is critical. In this study, the mucosal tissues (gills, foregut and hindgut) were collected from normal and infected fishes for transcriptome analysis. A total of 932,378,600 clean reads were obtained, of which approximately 80% were successfully mapped to the common carp genome. 577, 1,054 and 1,014 differential expressed genes (DEGs) were identified in the gills, foregut and hindgut, respectively. A quantitative polymerase chain reaction assay indicated that the DEGs expression in the foregut following SVCV infection was consistent with the transcriptome results. Among them, two key genes of the retinoic acid-inducible gene I (RIG-I)-like receptor family, melanoma-differentiation-associated gene 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2) (i.e., CcMDA5 and CcLGP2), underwent further analysis. Overexpression of CcMDA5 or CcLGP2 increased phosphorylation of TANK-binding kinase 1 and interferon regulatory factor 3 and the expression of interferon-1 (ifn-1), myxovirus resistance (mx), viperin and interferon-stimulated gene 15 (isg15), and inhibited SVCV replication in epithelioma papulosum cyprini cells. Furthermore, CcLGP2 significantly upregulated the CcMDA5-induced ifn-1 mRNA expression and the activation of the ifn-1 promoter. Finally, confocal microscopy and coimmunoprecipitation experiments revealed that CcLGP2 colocalizes and interacts with CcMDA5 via the C-terminal regulatory domain. This study provides essential gene resources for understanding the fish immune response to SVCV infection and sheds light on the potential role of fish LGP2 in the MDA5 regulation.

Natural History of Marburg Virus Infection to Support Medical Countermeasure Development

The Biomedical Advanced Research and Development Authority, part of the Administration for Strategic Preparedness and Response within the U.S. Department of Health and Human Services, recognizes that the evaluation of medical countermeasures under the Animal Rule requires well-characterized and reproducible animal models that are likely to be predictive of clinical benefit. Marburg virus (MARV), one of two members of the genus Marburgvirus, is characterized by a hemorrhagic fever and a high case fatality rate for which there are no licensed vaccines or therapeutics available. This natural history study consisted of twelve cynomolgus macaques challenged with 1000 PFU of MARV Angola and observed for body weight, temperature, viremia, hematology, clinical chemistry, and coagulation at multiple time points. All animals succumbed to disease within 8 days and exhibited signs consistent with those observed in human cases, including viremia, fever, systemic inflammation, coagulopathy, and lymphocytolysis, among others. Additionally, this study determined the time from exposure to onset of disease manifestations and the time course, frequency, and magnitude of the manifestations. This study will be instrumental in the design and development of medical countermeasures to Marburg virus disease.

Altered Maternal Antibody Profiles in Women With Human Immunodeficiency Virus Drive Changes in Transplacental Antibody Transfer

BACKGROUND

Human immunodeficiency virus (HIV)-exposed, uninfected (HEU) children have a higher risk of severe infection, but the causes are poorly understood. Emerging data point to altered antibody transfer in women with HIV (WHIV); however, specific perturbations and the influence of antiretroviral therapy (ART) and HIV viremia remain unclear.

METHODS

We evaluated antigen-specific transplacental antibody transfer across 14 antigens in paired maternal and umbilical cord plasma from 352 Ugandan women; 176 were WHIV taking ART. We measured antigen-specific immunoglobulin G (IgG) sub-class (IgG1, 2, 3, 4) levels and antibody Fcγ receptor (FcγRn, 2a, 2b, 3a, 3b) binding profiles. We used partial least squares discrimi-nant analysis to define antigen-specific transplacental antibody transfer features.

RESULTS

Global antibody transfer patterns were similar by maternal HIV serostatus, pointing to effective placental function in WHIV. However, HEU umbilical cord antibody profiles were altered, driven by perturbed WHIV seroprofiles, with higher levels of herpesvirus antibodies (P < .01 for Epstein-Barr virus, herpes simplex virus) and lower levels of classic vaccine-induced antibodies (P < .01 for tetanus, polio, Haemophilus influenzae type b), suggesting that umbilical cord antibody profile differences arise from imbalanced WHIV immunity. Abnormal WHIV antibody profiles were associated with HIV viremia, lower CD4 count, and postconception ART initiation (P = .01).

CONCLUSIONS

Perturbed immune-dominance profiles in WHIV shift the balance of immunity delivered to neonates. Perturbed HIV-associated maternal antibody profiles are a key determinant of com-promised neonatal immunity. Maternal vaccination interventions may promote transfer of relevant, effective antibodies to protect HEU children against early-life infections.

Diagnostic Accuracy of the Rapid Xpert HIV-1 Viral Load XC, Xpert HIV-1 Viral Load, & m-PIMA HIV-1/2 Viral Load in South African Clinics

BACKGROUND

We aimed to evaluate the analytic performance of 3 rapid HIV viral load assays: the novel Xpert HIV-1 VL XC (Xpert XC), Xpert HIV-1 VL (Xpert VL), and m-PIMA HIV-1/2 VL (m-PIMA).

SETTING

Two South African clinics.

METHODS

We conducted a prospective diagnostic accuracy study. Site-laboratory technicians and nurses used the Xpert XC, Xpert VL, and m-PIMA to test plasma samples from people with HIV receiving antiretroviral therapy. We compared results with the Roche cobas HIV-1 reference assay. We determined accuracy to detect viraemia at the World Health Organization (WHO) failure threshold of 1000 copies/mL on all 3 assays, and 50 and 200 copies/mL on the Xpert assays. We assessed the agreement using Bland-Altman plots.

RESULTS

We enrolled 140 participants (98 [70%] women, median age 37 years), who provided 189 paired samples at one or more timepoints. We tested 174 samples with the Xpert XC, 188 with the Xpert VL, and 128 with the m-PIMA. At 1000 copies/mL, sensitivity and specificity (95% confidence intervals) were 97% (82 to 100) and 98% (93 to 99) (Xpert XC), 100% (87 to 100) and 96% (91 to 98) (Xpert VL), and 92% (72 to 99) and 99% (93 to 100) (m-PIMA) respectively. At 50 copies/mL, sensitivity and specificity were 93% (81 to 98) and 96% (91 to 99) (Xpert XC), and 95% (84 to 99) and 95% (90 to 98) (Xpert VL) respectively. Mean bias was -0.10 (-0.54 to 0.34) log10 copies/mL (Xpert XC), 0.07 (-0.37 to 0.52) log10 copies/mL (Xpert VL), and -0.26 (-0.83 to 0.31) log10 copies/mL (m-PIMA).

CONCLUSIONS

In these South African clinics, the accuracy of all 3 assays was clinically acceptable to detect viraemia at the WHO failure threshold, whereas both Xpert assays were also accurate at detecting low-level viraemia.

Development of a novel Macaque-Tropic HIV-1 adapted to cynomolgus macaques

Macaque-tropic HIV-1 (HIV-1mt) variants have been developed to establish preferable primate models that are advantageous in understanding HIV-1 infection pathogenesis and in assessing the preclinical efficacy of novel prevention/treatment strategies. We previously reported that a CXCR4-tropic HIV-1mt, MN4Rh-3, efficiently replicates in peripheral blood mononuclear cells (PBMCs) of cynomolgus macaques homozygous for TRIMCyp (CMs^TC). However, the CMs^TC challenged with MN4Rh-3 displayed low viral loads during the acute infection phase and subsequently exhibited short-term viremia. These virological phenotypes in vivo differed from those observed in most HIV-1-infected people. Therefore, further development of the HIV-1mt variant was needed. In this study, we first reconstructed the MN4Rh-3 clone to produce a CCR5-tropic HIV-1mt, AS38. In addition, serial in vivo passages allowed us to produce a highly adapted AS38-derived virus that exhibits high viral loads (up to approximately 10⁶ copies ml^-1) during the acute infection phase and prolonged periods of persistent viremia (lasting approximately 16 weeks postinfection) upon infection of CMs^TC. Whole-genome sequencing of the viral genomes demonstrated that the emergence of a unique 15-nt deletion within the vif gene was associated with in vivo adaptation. The deletion resulted in a significant increase in Vpr protein expression but did not affect Vif-mediated antagonism of antiretroviral APOBEC3s, suggesting that Vpr is important for HIV-1mt adaptation to CMs^TC. In summary, we developed a novel CCR5-tropic HIV-1mt that can induce high peak viral loads and long-term viremia and exhibits increased Vpr expression in CMs^TC.

Analyzing Longitudinally Collected Viral Load Measurements in Youth With Perinatally Acquired HIV Infection: Problems and Possible Remedies

Human immunodeficiency virus (HIV) viral load (VL) is an important quantitative marker of disease progression and treatment response in people living with HIV infection, including children with perinatally acquired HIV. Measures of VL are often used to predict different outcomes of interest in this population, such as HIV-associated neurocognitive disorder. One popular approach to summarizing historical viral burden is the area under a time-VL curve (AUC). However, alternative historical VL summaries (HVS) may better answer the research question of interest. In this article, we discuss and contrast the AUC with alternative HVS, including the time-averaged AUC, duration of viremia, percentage of time with suppressed VL, peak VL, and age at peak VL. Using data on youth with perinatally acquired HIV infection from the Pediatric HIV/AIDS Cohort Study Adolescent Master Protocol, we show that HVS and their associations with full-scale intelligence quotient depend on when the VLs were measured. When VL measurements are incomplete, as can be the case in observational studies, analysis results may be subject to selection bias. To alleviate bias, we detail an imputation strategy, and we present a simulation study demonstrating that unbiased estimation of a historical VL summary is possible with a correctly specified imputation model.

Frequent detection but lack of infectivity of SARS-CoV-2 RNA in presymptomatic, infected blood donor plasma

Respiratory viruses such as influenza do not typically cause viremia; however, SARS-CoV-2 has been detected in the blood of COVID-19 patients with mild and severe symptoms. Detection of SARS-CoV-2 in blood raises questions about its role in pathogenesis as well as transfusion safety concerns. Blood donor reports of symptoms or a diagnosis of COVID-19 after donation (post-donation information, PDI) preceded or coincided with increased general population COVID-19 mortality. Plasma samples from 2,250 blood donors who reported possible COVID-19-related PDI were tested for the presence of SARS-CoV-2 RNA. Detection of RNAemia peaked at 9%-15% of PDI donors in late 2020 to early 2021 and fell to approximately 4% after implementation of widespread vaccination in the population. RNAemic donors were 1.2- to 1.4-fold more likely to report cough or shortness of breath and 1.8-fold more likely to report change in taste or smell compared with infected donors without detectable RNAemia. No infectious virus was detected in plasma from RNAemic donors; inoculation of permissive cell lines produced less than 0.7-7 plaque-forming units (PFU)/mL and in susceptible mice less than 100 PFU/mL in RNA-positive plasma based on limits of detection in these models. These findings suggest that blood transfusions are highly unlikely to transmit SARS-CoV-2 infection.

The Kinetics of SARS-CoV-2 Antibody Development Is Associated with Clearance of RNAemia

Persistent SARS-CoV-2 replication and systemic dissemination are linked to increased COVID-19 disease severity and mortality. However, the precise immune profiles that track with enhanced viral clearance, particularly from systemic RNAemia, remain incompletely defined. To define whether antibody characteristics, specificities, or functions that emerge during natural infection are linked to accelerated containment of viral replication, we examined the relationship of SARS-CoV-2-specific humoral immune evolution in the setting of SARS-CoV-2 plasma RNAemia, which is tightly associated with disease severity and death. On presentation to the emergency department, S-specific IgG3, IgA1, and Fc-γ-receptor (Fcγ R) binding antibodies were all inversely associated with higher baseline plasma RNAemia. Importantly, the rapid development of spike (S) and its subunit (S1/S2/receptor binding domain)-specific IgG, especially FcγR binding activity, were associated with clearance of RNAemia. These results point to a potentially critical and direct role for SARS-CoV-2-specific humoral immune clearance on viral dissemination, persistence, and disease outcome, providing novel insights for the development of more effective therapeutics to resolve COVID-19. IMPORTANCE We showed that persistent SARS-CoV-2 RNAemia is an independent predictor of severe COVID-19. We observed that SARS-CoV-2-targeted antibody maturation, specifically Fc-effector functions rather than neutralization, was strongly linked with the ability to rapidly clear viremia. This highlights the critical role of key humoral features in preventing viral dissemination or accelerating viremia clearance and provides insights for the design of next-generation monoclonal therapeutics. The main key points will be that (i) persistent SARS-CoV-2 plasma RNAemia independently predicts severe COVID-19 and (ii) specific humoral immune functions play a critical role in halting viral dissemination and controlling COVID-19 disease progression.

A Case Series of Children with Acute Hepatitis and Human Adenovirus Infection

BACKGROUND

Human adenoviruses typically cause self-limited respiratory, gastrointestinal, and conjunctival infections in healthy children. In late 2021 and early 2022, several previously healthy children were identified with acute hepatitis and human adenovirus viremia.

METHODS

We used International Classification of Diseases, 10th Revision, codes to identify all children (<18 years of age) with hepatitis who were admitted to Children's of Alabama hospital between October 1, 2021, and February 28, 2022; those with acute hepatitis who also tested positive for human adenovirus by whole-blood quantitative polymerase chain reaction (PCR) were included in our case series. Demographic, clinical, laboratory, and treatment data were obtained from medical records. Residual blood specimens were sent for diagnostic confirmation and human adenovirus typing.

RESULTS

A total of 15 children were identified with acute hepatitis - 6 (40%) who had hepatitis with an identified cause and 9 (60%) who had hepatitis without a known cause. Eight (89%) of the patients with hepatitis of unknown cause tested positive for human adenovirus. These 8 patients plus 1 additional patient referred to this facility for follow-up were included in this case series (median age, 2 years 11 months; age range, 1 year 1 month to 6 years 5 months). Liver biopsies indicated mild-to-moderate active hepatitis in 6 children, some with and some without cholestasis, but did not show evidence of human adenovirus on immunohistochemical examination or electron microscopy. PCR testing of liver tissue for human adenovirus was positive in 3 children (50%). Sequencing of specimens from 5 children showed three distinct human adenovirus type 41 hexon variants. Two children underwent liver transplantation; all the others recovered with supportive care.

CONCLUSIONS

Human adenovirus viremia was present in the majority of children with acute hepatitis of unknown cause admitted to Children's of Alabama from October 1, 2021, to February 28, 2022, but whether human adenovirus was causative remains unclear. Sequencing results suggest that if human adenovirus was causative, this was not an outbreak driven by a single strain. (Funded in part by the Centers for Disease Control and Prevention.).

Dietary supplementation of exopolysaccharides from Lactobacillus rhamnosus GCC-3 improved the resistance of zebrafish against spring viremia of carp virus infection

Spring viremia of carp virus (SVCV) can cause high mortality of fish. The aim of this study was to investigate the effects of Lactobacillus rhamnosus GCC-3 exopolysaccharides (GCC-3 EPS) on zebrafish (Danio rerio) infected with SVCV and elucidate the underlying mechanisms. Zebrafish were fed with a control diet or diet supplemented with 0.5% and 1% of GCC-3 EPS for 2 weeks. The results showed that supplementation of GCC-3 EPS significantly improved the survival rate of zebrafish compared with the control group. In addition, dietary 0.5% and 1% GCC-3 EPS significantly up-regulated the expression of genes related to type I interferon (IFN) antiviral immunity. Consistent with in vivo results, GCC-3 EPS significantly inhibited SVCV replication in zebrafish embryonic fibroblast (ZF4) cells while significantly increased the expression of type I IFN signaling pathway related genes. Furthermore, knocking down TANK-binding kinase 1 significantly blocked the antiviral effect of GCC-3 EPS. Dietary GCC-3 EPS improved gut microbiota, and the culture supernatant of GCC-3 EPS-associated microbiota significantly inhibited SVCV replication in ZF4 cells compared with the control-microbiota counterpart. In conclusion, our results indicate that dietary GCC-3 EPS can improve the resistance of zebrafish against SVCV infection, and the mechanism may involve enhanced type I interferon signaling.

A two-dimensional discrete delay-differential system model of viremia

A deterministic model is proposed to describe the interaction between an immune system and an invading virus whose target cells circulate in the blood. The model is a system of two ordinary first order quadratic delay-differential equations with stipulated initial conditions, whose coefficients are eventually constant, so that the system becomes autonomous. The long-term behavior of the solution is investigated with some success. In particular, we find two simple functions of the parameters of the model, whose signs often, but not always, determine whether the virus persists above a nonzero threshold in the circulation or heads toward extinction.

TRIM25 inhibits spring viraemia of carp virus replication by positively regulating RIG-I signaling pathway in common carp (Cyprinus carpio L.)

Common carp (Cyprinus carpio L.) is one of the most widely cultivated fish in China. Spring viraemia of carp virus (SVCV) is a highly pathogenic virus and has often caused excessive losses in carp pond fisheries. Innate immune play important roles against virus infection. To better understand the immune response of common carp against SVCV infection, transcriptome analysis was performed using the Illumina Novaseq 6000 platform. It was showed that a total of 3953 differentially expressed unigenes were identified, and the RLR signaling pathway were significantly enriched after SVCV infection. Subsequently, the role of RLR signaling pathway in SVCV infection was studied. The results showed that common carp RIG-I (CcRIG-I) and TRIM25 (CcTRIM25) significantly decreased the replication of SVCV by inducing the phosphorylation of TBK1, IRF3 and p65 and the expression of ifn-1, viperin, isg15 and mx. Further studies illustrated that CcTRIM25 could positive regulate CcRIG-I mediated downstream signaling pathway. Finally, the mechanism of CcTRIM25 promoting CcRIG-I-mediated signaling was investigated. CcTRIM25 could interact with the caspase activation and recruitment domain (CARD) of CcRIG-I and promoted K63-linked polyubiquitination of CcRIG-I. Altogether, the study revealed a mechanism of CcTRIM25 regulating CcRIG-I mediated immune response in SVCV infection.

Repeated exposure to heterologous hepatitis C viruses associates with enhanced neutralizing antibody breadth and potency

A prophylactic hepatitis C virus (HCV) vaccine that elicits neutralizing antibodies could be key to HCV eradication. However, the genetic and antigenic properties of HCV envelope (E1E2) proteins capable of inducing anti-HCV broadly neutralizing antibodies (bNAbs) in humans have not been defined. Here, we investigated the development of bNAbs in longitudinal plasma of HCV-infected persons with persistent infection or spontaneous clearance of multiple reinfections. By measuring plasma antibody neutralization of a heterologous virus panel, we found that the breadth and potency of the antibody response increased upon exposure to multiple genetically distinct infections and with longer duration of viremia. Greater genetic divergence between infecting strains was not associated with enhanced neutralizing breadth. Rather, repeated exposure to antigenically related, antibody-sensitive E1E2s was associated with potent bNAb induction. These data reveal that a prime-boost vaccine strategy with genetically distinct, antibody-sensitive viruses is a promising approach to inducing potent bNAbs in humans.

Oral Supplementation of Houttuynia cordata Extract Reduces Viremia in PRRSV-1 Modified-Live Virus-Vaccinated Pigs in Response to the HP-PRRSV-2 Challenge

This study evaluated the in vitro antiviral activities and the ex vivo immunomodulatory effects of Houttuynia cordata Thunb. (HC) ethanolic extracts in response to porcine reproductive and respiratory syndrome virus (PRRSV). In addition, this study evaluated the in vivo effects of oral supplementation of HC extract on immune responses to and cross-protective efficacy of PRRSV-1 modified-live virus (MLV) vaccine against the highly pathogenic (HP)-PRRSV-2 challenge. In vitro experiments demonstrated that HC extracted in either 50%, 70%, or 95% ethanol (referred to as HC50, HC70, and HC95, respectively) significantly interfered with PRRSV replication in MARC-145 cells. Ex vivo experiments revealed that all HC extracts significantly enhanced mRNA expressions of type I interferon-regulated genes, type I and II interferon (IFN), and pro- and anti-inflammatory cytokines in HP-PRRSV-2-inoculated monocyte-derived macrophages. An in vivo experiment included four groups of six pigs (4 weeks old; n = 24). Group 1 and group 2 were vaccinated with the PRRSV-1 MLV vaccine at 0 dpv (day post vaccination). Group 2 also received oral administration of HC50 extract at 0–49 dpv. Group 3 received the PRRSV-1 MLV vaccine solvent at 0 dpv, while group 4 served as strict control. Groups 1–3 were challenged intranasally with HP-PRRSV-2 at 28 dpv and immune-related and clinical parameters were monitored weekly until 49 dpv. Compared to group 1, group 2 demonstrated significantly increased IFN regulatory factor 3 mRNA expression of PRRSV-recalled peripheral blood mononuclear cells, and significantly reduced HP-PRRSV-2 viremia. No difference in PRRSV-specific antibody responses, rectal temperature, clinical scores, and average daily weight gain was detected. Our study reports the immunomodulatory and anti-PRRSV potentials of HC extract in PRRSV-1 MLV-vaccinated/HP-PRRSV-2 challenged pigs.

Human immune globulin treatment controls Zika viremia in pregnant rhesus macaques

There are currently no approved drugs to treat Zika virus (ZIKV) infection during pregnancy. Hyperimmune globulin products such as VARIZIG and WinRho are FDA-approved to treat conditions during pregnancy such as Varicella Zoster virus infection and Rh-incompatibility. We administered ZIKV-specific human immune globulin as a treatment in pregnant rhesus macaques one day after subcutaneous ZIKV infection. All animals controlled ZIKV viremia following the treatment and generated robust levels of anti-Zika virus antibodies in their blood. No adverse fetal or infant outcomes were identified in the treated animals, yet the placebo control treated animals also did not have signs related to congenital Zika syndrome (CZS). Human immune globulin may be a viable prophylaxis and treatment option for ZIKV infection during pregnancy, however, more studies are required to fully assess the impact of this treatment to prevent CZS.