Viral Control Research Articles

Viral Protein Dimerization Quality Control: A Design Strategy for a Potential Viral Inhibitor.

The global pharmaceutical market has been profoundly impacted by the coronavirus pandemic, leading to an increased demand for specific drugs. Consequently, drug resistance has prompted continuous innovation in drug design strategies to effectively combat resistant pathogens or disease variants. Protein dimers play crucial roles in vivo, including catalytic reactions, signal transduction, and structural stability. The site of action for protein dimerization modulators typically does not reside within the active site of the protein, thereby potentially impeding resistance development. Therefore, harnessing viral protein dimerization modulators could represent a promising avenue for combating viral infections. In this Perspective, we provide a detailed introduction to the design principles and applications of dimerization modulators in antiviral research. Furthermore, we analyze various representative examples to elucidate their modes of action while presenting our perspective on dimerization modulators along with the opportunities and challenges associated with this groundbreaking area of investigation.

Adherence, Adverse Events and Viral Control among Children and Adolescents with HIV in Zambia Switched to an Integrase Inhibitor Regimen.

Based on recent World Health Organization recommendations, there has been a large-scale transition in Sub-Saharan Africa to integrase inhibitor (II)-based antiretroviral therapy (ART) regimens. This study was conducted at an urban referral center in Lusaka, Zambia. This study included 297 children and adolescents with HIV (CAWH) on ART for one year prior to enrollment and followed for 1-4 years after enrollment. ART adherence, ART regimen, and viral load were assessed periodically. Structured interviews were conducted with a subset of 95 children to assess adherence barriers and side effects. Children on protease inhibitor (PI)-based regimens were more likely to report adherence problems than children taking II- or Efavirenz-based regimens (10% vs. 28%, p=0.03) and noted more days with missed doses (median 1 vs. 0, p=0.02). In interviews, the most common reasons given for poor adherence included bad medication taste, not being home when medications were due, and perceived side effects. The PI group was more likely to report that taste was a problem affecting adherence (22% vs. 4%, p=0.05) and headache as an ART side effect (17% vs. 4%, p=0.05). Switching from a PI- to an II-based regimen was associated with improved adherence (72% vs. 92%, p=0.01) and an undetectable viral load (67% vs. 78%). Switching CAWH from PI-based to II-based regimens has many advantages including superior side effect profiles, adherence, and viral suppression. PI taste aversion may be a significant contributor to pediatric adherence issues. Palatability should be considered in pediatric HIV drug development.

Epigenetic tuning of PD-1 expression improves exhausted T cell function and viral control.

PD-1 is a key negative regulator of CD8+ T cell activation and is highly expressed by exhausted T cells in cancer and chronic viral infection. Although PD-1 blockade can improve viral and tumor control, physiological PD-1 expression prevents immunopathology and improves memory formation. The mechanisms driving high PD-1 expression in exhaustion are not well understood and could be critical to disentangling its beneficial and detrimental effects. Here, we functionally interrogated the epigenetic regulation of PD-1 using a mouse model with deletion of an exhaustion-specific PD-1 enhancer. Enhancer deletion exclusively alters PD-1 expression in CD8+ T cells in chronic infection, creating a 'sweet spot' of intermediate expression where T cell function is optimized compared to wild-type and Pdcd1-knockout cells. This permits improved control of chronic infection without additional immunopathology. Together, these results demonstrate that tuning PD-1 via epigenetic editing can reduce CD8+ T cell dysfunction while avoiding excess immunopathology.

NKG2C and NKG2A coexpression defines a highly functional antiviral NK population in spontaneous HIV control.

Elite controllers (ECs), a unique group of people with HIV (PWH), exhibit remarkable control of viral replication in the absence of antiretroviral therapy. In this study, we comprehensively characterized the NK cell repertoire in ECs after long-term viral control. Phenotypic profiling of NK cells revealed profound differences compared with other PWH, but marked similarities to uninfected individuals, with a distinctive prevalence of NKG2C+CD57+ memory-like NK cells. Functional analyses indicated that ECs had limited production of functional molecules upon NK stimulation and consequently reduced natural cytotoxicity against non-HIV target cells. Importantly, ECs showed an exceptional ability to kill primary HIV-infected cells by the antibody-dependent cell cytotoxicity adaptive mechanism, which was achieved by a specific memory-like NK population expressing CD16, NKG2A, NKG2C, CD57, and CXCR3. In-depth single-cell RNA-seq unveiled a unique transcriptional signature in these NK cells linked to increased cell metabolism, migration, chemotaxis, effector functions, cytokine secretion, and antiviral response. Our findings underscore a pivotal role of NK cells in the immune control of HIV and identify specific NK cells as emerging targets for immunotherapies.

Optical biosensor based on the dual-functional gold nanoparticles for rapid and accurate multiplex detection of influenza A and B viruses

Due to the global pandemic of influenza and related respiratory diseases, rapid and accurate detection is in high demand to control virus spread and facilitate early treatment. However, most current molecular detection methods either require long turnaround times, suffer from low sensitivity and/or can only detect single pathogens. To overcome these challenges, we constructed a novel colorimetric gold nanoparticle (AuNPs) biosensor containing functionalized probes to detect multiple targets simultaneously. Utilizing the salt aging method, AuNPs were functionalized by the designed oligonucleotides to fabricate biosensors. This biosensor can show visible color change within 20 min, and could minimally detect the target influenza viruses at 10 nM. This detection technique presents high sensitivity in a short time, meanwhile identifying two different influenza viruses simultaneously. It opens a window to a multiplex-in-one strategy for a clinical viral diagnostic.

Zika virus NS3 drives the assembly of a viroplasm-like structure.

Zika virus (ZIKV) is a mosquito-transmitted flavivirus that caused an epidemic in 2015-2016 in the Americas and raised serious global health concerns due to its association with congenital brain developmental defects in infected pregnancies. Upon infection, ZIKV assembles virus particles in a virus-generated toroidal compartment next to the nucleus called the replication factory, or viroplasm, which forms by remodeling the host cell endoplasmic reticulum (ER). How the viral proteins control viroplasm assembly remains unknown. Here we show that the ZIKV non-structural protein 3 (NS3) is sufficient to drive the assembly of a viroplasm-like structure (VLS) in human cells. NS3 encodes a dual-function protease and RNA helicase. The VLS is similar to the ZIKV viroplasm in its assembly near centrosomes at the nuclear periphery, its deformation of the nuclear membrane, its recruitment of ER, Golgi, and dsRNA, and its association with microtubules at its surface. While sufficient to generate a VLS, NS3 is less efficient in several aspects compared to viroplasm formation upon ZIKV infection. We further show that the helicase domain and not the protease domain is required for optimal VLS assembly and dsRNA recruitment. Overall, this work advances our understanding of the mechanism of viroplasm assembly by ZIKV and likely will extend to other flaviviruses.

Cognitive performance, neuropsychiatric symptoms, and cerebrospinal fluid viral control following programmatic switch from efavirenz-based to dolutegravir-based antiretroviral therapy in South Africa (CONNECT): a prospective cohort study

Both efavirenz and dolutegravir have been associated with neuropsychiatric side-effects and cognitive impairment. Furthermore, cerebrospinal fluid (CSF) HIV RNA escape has not been comprehensively studied in African populations. We aimed to examine changes in cognition, neuropsychiatric symptoms, and CSF viral control associated with the widespread switch from efavirenz-based to dolutegravir-based antiretroviral therapy (ART). This prospective cohort study of people with HIV and people without HIV recruited adults with HIV (aged 18-55 years) from the Gugulethu Community Health Centre in a low-income periurban area of Cape Town, South Africa. Eligible participants had been receiving efavirenz-based ART for at least 1 year and were identified by the clinic to switch to dolutegravir-based ART as part of the national programmatic switch. Participants were studied at baseline and followed up at 1 year after switch to dolutegravir. People without HIV were recruited from the same area, matched for age and gender, and followed up at the same time interval. People with HIV and people without HIV underwent comprehensive cognitive testing over seven domains and measures of functioning, mood, anxiety, and sleep. People with HIV had CSF sampling for HIV RNA quantification. Between Aug 12, 2019, and Sept 16, 2022, we recruited 178 people with HIV and 95 people without HIV. 145 (81%) of 178 people with HIV and 40 (66%) of 60 people without HIV who were offered underwent follow-up. Global cognitive performance was 2·57 T score points lower in people with HIV than in people without HIV at baseline (p=0·0008). At follow-up, cognition in people with HIV improved more than practice effects observed in people without HIV (coefficient 1·40, 95% CI 0·48-2·32, p=0·0028) and no significant difference in cognitive performance between groups was apparent (51·43 vs 52·73; p=0·22). Sleep quality improved following the switch (risk ratio 0·90, 95% CI 0·84-0·95; p=0·0002), driven mainly by indicators of disturbed sleep. There were nine incident cases of depression, although baseline differences were present. There was one case (1%) of CSF escape at baseline and three cases (4%) at follow-up; all were at low levels or resolved with repeated sampling. Improvements in cognition and sleep are probably related to switching from efavirenz. However, the possible increase in depression warrants further examination. Cognitive performance in virally supressed African people with HIV receiving dolutegravir-based therapy is similar to people without HIV. CSF escape is uncommon on both efavirenz-based and dolutegravir-based therapy. South African Medical Research Council and UK Medical Research Council, Newton Fund.

Antibiotic De-escalation Patterns and Outcomes in Critically Ill Patients with Suspected Pneumonia as Informed by Bronchoalveolar Lavage Results.

Antibiotic stewardship in critically ill pneumonia patients is crucial yet challenging, partly due to the limited diagnostic yield of noninvasive infectious tests. In this study, we report an antibiotic prescription pattern informed by bronchoalveolar lavage (BAL) results, where clinicians de-escalate antibiotics based on the combination of quantitative cultures and multiplex PCR rapid diagnostic tests. We analyzed data from SCRIPT, a single-center prospective cohort study of mechanically ventilated patients who underwent a BAL for suspected pneumonia. We used the novel Narrow Antibiotic Therapy (NAT) score to quantify day-by-day antibiotic prescription pattern for each suspected pneumonia episode etiology (bacterial, viral, mixed bacterial/viral, microbiology-negative, and non-pneumonia control). We also analyzed and compared clinical outcomes for each pneumonia etiology, including unfavorable outcomes (a composite of in-hospital mortality, discharge to hospice, or requiring lung transplantation during hospitalization), duration of ICU stay, and duration of intubation. Clinical outcomes were compared with the Mann-Whitney U test and Fisher's exact test. We included 686 patients with 927 pneumonia episodes. NAT score analysis indicated that an antibiotic de-escalation pattern was evident in all pneumonia etiologies except resistant bacterial pneumonia. Microbiology-negative pneumonia was treated similarly to susceptible bacterial pneumonia in terms of antibiotic spectrum. Over a quarter of the time in viral pneumonia episodes, antibiotics were completely discontinued. Unfavorable outcomes were comparable across all pneumonia etiologies. Patients with viral and mixed bacterial/viral pneumonia had longer durations of ICU stay and intubation. BAL quantitative cultures and multiplex PCR rapid diagnostic tests resulted in prompt antibiotic de-escalation in critically ill pneumonia patients. There was no evidence of increased incidence of unfavorable outcomes.

Multi-omics analysis of SIV-specific CD8+ T cells in multiple anatomical sites.

CD8+ T cells exert immunological pressure against immunodeficiency lentiviruses. In previous studies, we examined the TCR repertoire of CD8+ T cells specific for a single SIV immunodominant epitope, Gag-CM9, throughout SIV infection or after vaccination, and across multiple anatomic sites. We identified both tissue specific TCR sequences and TCRs shared by multiple anatomical sites. Here we use single cell RNA sequencing to evaluate if the tissue localization or TCR sequence of a CM9-specific CD8+ T cell corresponds with unique transcriptomics. CM9-specific CD8+ T cells were sorted from blood, lymph nodes, spleen, and liver from SIV infected rhesus macaques with progressive SIV infection and in animals who spontaneously control SIV replication after cessation of antiretroviral therapy. The cells were processed through a single cell sequencing protocol, creating a TCR amplified library and an RNA gene expression library corresponding to individual cells. Gene set enrichment analysis revealed no distinct transcriptional profiles for CM9 specific CD8+ T cells between different anatomical sites and between cells with shared or tissue specific TCRs. Similarly, no clear transcriptional profiles were associated with clonotypes which were shared across individual animals. However, CM9 specific CD8+ T cells from posttreatment controllers did exhibit enrichment of pathways associated with cellular activation compared to progressively infected animals, suggesting that altered transcription in distinct cellular pathways in antigen specific CD8+ T cells may associate with viral control. Together, these studies represent a thorough analysis of the relationship between anatomical and clonal origin, and the transcriptional profile of antigen specific CD8+ T cells and unravel pathways that may be important for CD8+ T cell mediated control of SIV replication.

Prion protein alters viral control and enhances pathology after perinatal cytomegalovirus infection

Cytomegalovirus (CMV) infection poses risks to newborns, necessitating effective therapies. Given that the damage includes both viral infection of brain cells and immune system-related damage, here we investigate the involvement of cellular prion protein (PrP), which plays vital roles in neuroprotection and immune regulation. Using a murine model, we show the role of PrP in tempering neonatal T cell immunity during CMV infection. PrP-null mice exhibit enhanced viral control through elevated virus-specific CD8 T cell responses, leading to reduced viral titers and pathology. We further unravel the molecular mechanisms by showing CMV-induced upregulation followed by release of PrP via the metalloproteinase ADAM10, impairing CD8 T cell response specifically in neonates. Additionally, we confirm PrP downregulation in human CMV (HCMV)-infected fibroblasts, underscoring the broader relevance of our observations beyond the murine model. Furthermore, our study highlights how PrP, under the stress of viral pathogenesis, reveals its impact on neonatal immune modulation.

Comparison of protection against mpox following mRNA or modified vaccinia Ankara vaccination in nonhuman primates

In 2022, mpox virus (MPXV) spread worldwide, causing 99,581 mpox cases in 121 countries. Modified vaccinia Ankara (MVA) vaccine use reduced disease in at-risk populations but failed to deliver complete protection. Lag in manufacturing and distribution of MVA resulted in additional MPXV spread, with 12,000 reported cases in 2023 and an additional outbreak in Central Africa of clade I virus. These outbreaks highlight the threat of zoonotic spillover by Orthopoxviruses. mRNA-1769, an mRNA-lipid nanoparticle (LNP) vaccine expressing MPXV surface proteins, was tested in a lethal MPXV primate model. Similar to MVA, mRNA-1769 conferred protection against challenge and further mitigated symptoms and disease duration. Antibody profiling revealed a collaborative role between neutralizing and Fc-functional extracellular virion (EV)-specific antibodies in viral restriction and ospinophagocytic and cytotoxic antibody functions in protection against lesions. mRNA-1769 enhanced viral control and disease attenuation compared with MVA, highlighting the potential for mRNA vaccines to mitigate future pandemic threats.

In depth analysis of the HIV reservoir confirms effectiveness and safety of DTG/3TC in a phase 4 randomized controlled switch trial (RUMBA).

Reducing the number of active compounds for lifelong HIV treatment is of interest, especially to reduce potential long-term side effects. So far, available data assessing viral control, support the robustness and safety of 2DR (2-drug regimen) ART compared to 3DR. However, further in-depth investigations of the viral reservoirs are mandatory to guarantee long-term safety of these regimens regarding stable intact HIV-1 DNA copies, HIV-1 RNA transcripts and sustained immunological control. The Rumba study is the first prospective randomized controlled trial evaluating the impact of switch from 3DR to 2DR on the viral reservoir. Participants on any stable 2nd generation INSTI-based 3DR regimen with HIV-1 RNA<50 copies/ml plasma for at least 3 months were randomized to switch to dolutegravir/lamivudine (DTG/3TC, N=89) or to switch or stay on bictegravir/emtricitabine/tenofovir alafenamide (B/F/TAF, N=45). After 48 weeks, virological, immunological and metabolic parameters were evaluated. We did not observe a significant difference in change over time in the mean number of intact HIV-1 DNA copies/million CD4+ T cells with DTG/3TC compared to B/F/TAF. There was no evidence in this study that switching to DTG/3TC increased the active reservoir by HIV-1 transcription. No significant changes in pro-inflammatory cytokines or major immune cell subsets were observed. Changes in exhaustion and activation of specific cellular subsets were small and bidirectional. Metabolic outcomes are similar between the treatment regimens. This study confirms the safety of DTG/3TC compared to B/F/TAF through viral control after in-depth investigations of the intact HIV-1 reservoir, HIV-1 transcription and inflammatory markers.

Mucosal and systemic immune correlates of viral control after SARS-CoV-2 infection challenge in seronegative adults.

Human infection challenge permits in-depth, early, and pre-symptomatic characterization of the immune response, enabling the identification of factors that are important for viral clearance. Here, we performed intranasal inoculation of 34 young adult, seronegative volunteers with a pre-Alpha severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain. Of these participants, 18 (53%) became infected and showed an interferon-dominated mediator response with divergent kinetics between nasal and systemic sites. Peripheral CD4+ and CD8+ T cell activation and proliferation were early and robust but showed distinct kinetic and phenotypic profiles; antigen-specific T cells were largely CD38+Ki67+ and displayed central and effector memory phenotypes. Both mucosal and systemic antibodies became detectable around day 10, but nasal antibodies plateaued after day 14 while circulating antibodies continued to rise. Intensively granular measurements in nasal mucosa and blood allowed modeling of immune responses to primary SARS-CoV-2 infection that revealed CD8+ T cell responses and early mucosal IgA responses strongly associated with viral control, indicating that these mechanisms should be targeted for transmission-reducing intervention.

Abstract MP04: Brain miR-410-3p Expression Sex-dependently Reduces Ang-II-induced Hypertension

Dysregulation of microRNA (miRNA) is associated with hypertension and other diseases. We previously observed direct interaction of miR-410-3p with AT 1 R and sex-dependent downregulation of miR-410-3p in the hypothalamus of a mouse cardiometabolic disease (CMD) model, suggesting a possible involvement in the development of CMD through modulation of the renin-angiotensin system. To further investigate the role of hypothalamic miR-410-3p expression as a therapeutic target for hypertension, acute Ang-II injection and chronic infusion experiments were performed. In acute experiments, C57BL/6J mice (males and females) were injected with Lenti-miR-410-3p or a control virus (icv, 2 µl, n=5-6). After 3 weeks, mice were anesthetized and a catheter was inserted to the carotid artery for blood pressure (BP) monitoring, followed by a bolus icv injection of Ang-II (200 ng/200 nl). Changes in systolic BP (ΔSBP) were recorded. In chronic experiments, mice were fed with a high calorie diet for 2 months before icv virus injection (2 µl). Telemetry probes (DSI) were implanted for conscious BP monitoring. Three weeks following virus injection, all mice were infused with Ang-II using osmotic minipumps (sc, 600 ng/kg/min, 14 days) to induce CMD. BP was recorded weekly and 24 h average of mean arterial pressure (MAP) was calculated. Acute Ang-II injection-induced pressor responses were similar in males (ΔSBP; 22.2±4.7 mmHg) and females (20.6±6.5 mmHg) transfected with the control virus. In lenti-miR-410-3p transfected mice, the pressor responses were blunted in both males (6.7±4.8 mmHg, P &lt;0.001 vs. control) and females (10.9±4.7 mmHg, P&lt;0.05 vs. control), with a greater reduction observed in males (69.8% vs. 47%). In the HCD model, baseline MAP was not different between male control and Lenti-miR-410, or female control and Lenti-miR-410 group. Following Ang-II infusion, MAP was increased in both sexes treated with control virus. Interestingly, this increase was blunted by Lenti-miR-410-3p expression in males (137.3 ± 9.4 vs. 160.7 ± 4.3 mmHg, P =0.05) but not in females (140.4±4.6 vs. 140.5 ± 4.2 mmHg). These data are aligned with our previous findings that male mice had higher expression of hypothalamic AT 1 R than in females in CMD. In summary, miR-410-3p inhibits both acute and chronic Ang-II induced increases in BP in a sex-dependent manner, with more profound effects in males. miR-410-3p could be a new strategy for the treatment of hypertension in CMD.

The adaptive and innate immune systems coordinate for successful control of CMV infection

Previous studies of the immune control of cytomegalovirus infection have primarily focused on analysis of the traditional adaptive T-cell response. Donadeu etal. bring a new perspective through evaluation of multiple adaptive and innate immune subtypes in parallel with cytomegalovirus-specific cell-mediated immunity in a prospective cohort of kidney transplant recipients with findings validated in 2 independent studies. Identification of a natural killer T-cell subtype associated with cell-mediated immunity and freedom from cytomegalovirus infection demonstrates the importance of the coordinated innate and adaptive immune response for effective viral control.

Association between HIV and cytomegalovirus and neurocognitive outcomes among children with HIV.

Children with HIV may experience adverse neurocognitive outcomes despite antiretroviral therapy (ART). Cytomegalovirus (CMV) is common in children with HIV. Among children on ART, we examined the influences of early HIV viral load (VL) and CMV DNA on neurocognition. We determined the association between pre-ART VL, cumulative VL, and CMV viremia and neurocognition using data from a cohort study. Children who initiated ART before 12 months of age were enrolled from 2007-2010 in Nairobi, Kenya. Blood was collected at enrollment and every 6 months thereafter. Four neurocognitive assessments with 12 domains were conducted when children were a median age of 7 years. Primary outcomes included cognitive ability, executive function, attention, and motor. Generalized linear models were used to determine associations between HIV VL (pre-ART and cumulative; N = 38) and peak CMV DNA (by 24 months of age; N = 20) and neurocognitive outcomes. In adjusted models, higher peak CMV viremia by 24 months of age was associated with lower cognitive ability and motor z-scores. Higher pre-ART HIV VL was associated with lower executive function z-scores. Among secondary outcomes, higher pre-ART VL was associated with lower mean nonverbal and metacognition z-scores. Higher pre-ART VL and CMV DNA in infancy were associated with lower executive function, nonverbal and metacognition scores and cognitive ability scores in childhood, respectively. These findings suggest long-term benefits of early HIV viral suppression and CMV control on neurocognition.

Attenuated effector T cells are linked to control of chronic HBV infection

Hepatitis B virus (HBV)-specific CD8+ T cells play a dominant role during acute-resolving HBV infection but are functionally impaired during chronic HBV infection in humans. These functional deficits have been linked with metabolic and phenotypic heterogeneity, but it has remained unclear to what extent different subsets of HBV-specific CD8+ T cells still suppress viral replication. We addressed this issue by deep profiling, functional testing and perturbation of HBV-specific CD8+ T cells during different phases of chronic HBV infection. Our data revealed a mechanism of effector CD8+ T cell attenuation that emerges alongside classical CD8+ T cell exhaustion. Attenuated HBV-specific CD8+ T cells were characterized by cytotoxic properties and a dampened effector differentiation program, determined by antigen recognition and TGFβ signaling, and were associated with viral control during chronic HBV infection. These observations identify a distinct subset of CD8+ T cells linked with immune efficacy in the context of a chronic human viral infection with immunotherapeutic potential.

CD4+ and CD8+ T cells are required to prevent SARS-CoV-2 persistence in the nasal compartment.

SARS-CoV-2 infection induces the generation of virus-specific CD4+ and CD8+ effector and memory T cells. However, the contribution of T cells in controlling SARS-CoV-2 during infection is not well understood. Following infection of C57BL/6 mice, SARS-CoV-2-specific CD4+ and CD8+ T cells are recruited to the respiratory tract, and a vast proportion secrete the cytotoxic molecule granzyme B. Using depleting antibodies, we found that T cells within the lungs play a minimal role in viral control, and viral clearance occurs in the absence of both CD4+ and CD8+ T cells through 28 days postinfection. In the nasal compartment, depletion of both CD4+ and CD8+ T cells, but not individually, results in persistent, culturable virus replicating in the nasal epithelial layer through 28 days postinfection. Viral sequencing analysis revealed adapted mutations across the SARS-CoV-2 genome, including a large deletion in ORF6. Overall, our findings highlight the importance of T cells in controlling virus replication within the respiratory tract during SARS-CoV-2 infection.

RSV and rhinovirus increase pneumococcal carriage acquisition and density, whereas nasal inflammation is associated with bacterial shedding

Epidemiological studies report the impact of co-infection with pneumococcus and respiratory viruses upon disease rates and outcomes, but their effect on pneumococcal carriage acquisition and bacterial load is scarcely described. Here, we assess this by combining natural viral infection with controlled human pneumococcal infection in 581 healthy adults screened for upper respiratory tract viral infection before intranasal pneumococcal challenge. Across all adults, respiratory syncytial virus (RSV) and rhinovirus asymptomatic infection confer a substantial increase in secondary infection with pneumococcus. RSV also has a major impact on pneumococcal density up to 9days post challenge. We also study rates and kinetics of bacterial shedding through the nose and oral route in a subset. High levels of pneumococcal colonization density and nasal inflammation are strongly correlated with increased odds of nasal shedding as opposed to cough shedding. Protection against respiratory viral infections and control of pneumococcal density may contribute to preventing pneumococcal disease and reducing bacterial spread.

Exploring the Effectiveness of Acyclovir against Ranaviral Thymidine Kinases: Molecular Docking and Experimental Validation in a Fish Cell Line.

The effectiveness of acyclovir, a selective anti-herpesvirus agent, was tested both in silico and in vitro against two ranaviruses, namely the European catfish virus (ECV) and Frog virus 3 (FV3). ECV can cause significant losses in catfish aquaculture, while FV3 poses a risk to vulnerable amphibian populations. The genome of ranaviruses encodes thymidine kinases (TKs) similar to those of herpesviruses. Molecular docking simulations demonstrated that the acyclovir molecule can bind to the active sites of both investigated viral TKs in an orientation conducive to phosphorylation. Subsequently, the antiviral effect of acyclovir was tested in vitro in Epithelioma Papulosum Cyprini (EPC) cells with endpoint titration and qPCR. Acyclovir was used at a concentration of 800 µM, which significantly reduced the viral loads and titers of the ranaviruses. A similar reduction rate was observed with Ictalurid herpesvirus 2, which was used as a positive control virus. These promising results indicate that acyclovir might have a wider range of uses; besides its effectiveness against herpesviruses, it could also be used against ranavirus infections.