Virus Inoculum Research Articles

Analysis of Virus Population Profiles within Pigs Infected with Virulent Classical Swine Fever Viruses: Evidence for Bottlenecks in Transmission but Absence of Tissue-Specific Virus Variants.

Classical swine fever virus (CSFV) contains a specific motif within the E2 glycoprotein that differs between strains of different virulence. In the highly virulent CSFV strain Koslov, this motif comprises residues S763/L764 in the polyprotein. However, L763/P764 represent the predominant alleles in published CSFV genomes. In this study, changes were introduced into the CSFV strain Koslov (here called vKos_SL) to generate modified CSFVs with substitutions at residues 763 and/or 764 (vKos_LL, vKos_SP, and vKos_LP). The properties of these mutant viruses, in comparison to those of vKos_SL, were determined in pigs. Each of the viruses was virulent and induced typical clinical signs of CSF, but the vKos_LP strain produced them significantly earlier. Full-length CSFV cDNA amplicons (12.3 kb) derived from sera of infected pigs were deep sequenced and cloned to reveal the individual haplotypes that contributed to the single-nucleotide polymorphism (SNP) profiles observed in the virus population. The SNP profiles for vKos_SL and vKos_LL displayed low-level heterogeneity across the entire genome, whereas vKos_SP and vKos_LP displayed limited diversity with a few high-frequency SNPs. This indicated that vKos_SL and vKos_LL exhibited a higher level of fitness in the host and more stability at the consensus level, whereas several consensus changes were observed in the vKos_SP and vKos_LP sequences, pointing to adaptation. For each virus, only a subset of the variants present within the virus inoculums were maintained in the infected pigs. No clear tissue-dependent quasispecies differentiation occurred within inoculated pigs; however, clear evidence for transmission bottlenecks to contact animals was observed, with subsequent loss of sequence diversity.IMPORTANCE The surface-exposed E2 protein of classical swine fever virus is required for its interaction with host cells. A short motif within this protein varies between strains of different virulence. The importance of two particular amino acid residues in determining the properties of a highly virulent strain of the virus has been analyzed. Each of the different viruses tested proved highly virulent, but one of them produced earlier, but not more severe, disease. By analyzing the virus genomes present within infected pigs, it was found that the viruses which replicated within inoculated animals were only a subset of those within the virus inoculum. Furthermore, following contact transmission, it was shown that a very restricted set of viruses had transferred between animals. There were no significant differences in the virus populations present in various tissues of the infected animals. These results indicate mechanisms of virus population change during transmission between animals.

Magnesium Functions as Superior Co-factor for Measuring Reverse Transcriptase Activity of HIV-1, HIV-2, and SIV

This study compared different detection methods of human/simian immunodeficiency virus (HIV/SIV) infections in the cell line systems; notably, i) Indirect immunofluorescence assay (IFA), ii) integrated proviral DNA detection, iii) detection of syncytia, iv) measurement of reverse transcriptase (RT) activity. RTs of various retroviruses require cations, including Mg2+, Mn2+, Ni2+, and Cu2+, for their enzyme-activities. The study further compared the roles of Mg2+ and Mn2+ as cofactors for RT activities of freshly harvested HIV-1, HIV-2, and SIV. The NP-2/CD4/coreceptor cells were seeded for overnight and infected with viral inoculums at a multiplicity of infection (MOI) 1.0. The cells were passaged regularly in a 2-3 days interval and maintained up to 2 weeks. Infected cells were detected by indirect immunofluorescence assay (IFA). Multinucleated giant cells (MGC) in syncytia were quantified by Giemsa-staining. Proviral DNA was detected by PCR, and reverse transcriptase (RT) activity was measured. Two different cations, Mg2+ and Mn2+ were used as cofactors for RT assay. We found all the strains of HIV-1, HV-2 and SIV to infection in the cell line conveniently. IFA had identified all the viral infections in the infected cells. Proviral DNA detection, syncytia formation was observed in the infected cells. We found a better performance of Mg2+ as cofactor over Mn2+ in RT assay for HIV-1, HIV-2, SIV. Different four detection techniques of HIV/SIV infections show high level of agreement in the NP-2-based cell line system. Mg2+ remains a better cofactor for RT.

Masks Do More Than Protect Others During COVID-19: Reducing the Inoculum of SARS-CoV-2 to Protect the Wearer.

Although the benefit of population-level public facial masking to protect others during the COVID-19 pandemic has received a great deal of attention, we discuss for one of the first times the hypothesis that universal masking reduces the “inoculum” or dose of the virus for the mask-wearer, leading to more mild and asymptomatic infection manifestations. Masks, depending on type, filter out the majority of viral particles, but not all. We first discuss the near-century-old literature around the viral inoculum and severity of disease (conceptualized as the LD50 or lethal dose of the virus). We include examples of rising rates of asymptomatic infection with population-level masking, including in closed settings (e.g., cruise ships) with and without universal masking. Asymptomatic infections may be harmful for spread but could actually be beneficial if they lead to higher rates of exposure. Exposing society to SARS-CoV-2 without the unacceptable consequences of severe illness with public masking could lead to greater community-level immunity and slower spread as we await a vaccine. This theory of viral inoculum and mild or asymptomatic disease with SARS-CoV-2 in light of population-level masking has received little attention so this is one of the first perspectives to discuss the evidence supporting this theory.

Developing an Ephestia kuehniella Hemocyte Cell Line to Assess the Bio-Insecticidal Potential of Microencapsulated Helicoverpa armigera Nucleopolyhedrovirus Against Cotton Bollworm (Lepidoptera: Noctuidae) Larva.

Helicoverpa armigera Nucleopolyhedrovirus (HearNPV) (genus: Alphabaculovirus, incertae sedis: Baculoviridae) has been used to control Helicoverpa armigera (Hübner). A reproducible and susceptible cell line was prepared from the hemocytes of Ephestia kuehniella in Grace and Ex-Cell 420 media. The population doubling time of these cloned cell cultures during the logarithmic phase were about 2.3 and 3.7 d for Ex-Cell 420 and Grace's media, respectively. When 60% confluence occurred, cells were infected by viral inoculums. All biochemical compounds were significantly changed relevant to cellular metabolism due to HearNPV infection. In order to improve its stability, two polymer formulations were used, i.e., formulation A (sodium alginate, gelatin, starch, and molasses) and formulation B (cottonseed kernel extract, Bran, glycerol, boric acid, egg white, and sugar). Formulant A provided high photostability by exhibiting 83.2 ± 3% efficacy and 88.66 ± 2.1% original activities remaining after 72 h UV exposure. Percentage original activity remaining of unformulated HearNPV and formulated mixture of B was 38.66 ± 2.6% and 9.33 ± 1.3%, respectively, after 72 h UV-irradiation. The virulence of the HearNPV proliferated from the Ex-Cell medium was similar to the virulence of wild-type HearNPV with LC50 of 7.7×105 OBs/ml. Formulant A, revealed only 20.0 ± 1% reduction in efficacy while the unformulated virus and formulant B faced a reduction of 90.0 ± 3% and 64.0 ± 2% after 72 h of UVA irradiation. Formulant A thus showed a high potential to protect HearNPVs microparticles against UV-inactivation suggesting a new platform for more efficient biological-management of cotton bollworm (specific name Helicoverpa armigera, genus: Helicoverpa, Lepidoptera: Noctuidae) in vivo.

COVID-19: Does the Infectious Inoculum Dose-Response Relationship Contribute to Understanding Heterogeneity in Disease Severity and Transmission Dynamics?

The variation in the speed and intensity of SARS-CoV-2 transmission and severity of the resulting COVID-19 disease are still imperfectly understood. We postulate a dose-response relationship in COVID-19, and that “the dose of virus in the initial inoculum” is an important missing link in understanding several incompletely explained observations in COVID-19 as a factor in transmission dynamics and severity of disease. We hypothesize that: (1) Viral dose in inoculum is related to severity of disease, (2) Severity of disease is related to transmission potential, and (3) In certain contexts, chains of severe cases can build up to severe local outbreaks, and large-scale intensive epidemics. Considerable evidence from other infectious diseases substantiates this hypothesis and recent evidence from COVID-19 points in the same direction. If proven, our hypothesis could explain several of these lacunae in understanding the ongoing COVID-19 pandemic and strengthen the scientific basis for deciding priority containment measures in various contexts.

Social Distancing Alters the Clinical Course of COVID-19 in Young Adults: A Comparative Cohort Study.

BackgroundSocial distancing and stringent hygiene seem effective in reducing the number of transmitted virus particles, and therefore the infectivity, of coronavirus disease 2019 (COVID-19) and could alter the mode of transmission of the disease. However, it is not known if such practices can change the clinical course in infected individuals.MethodsWe prospectively studied an outbreak of COVID-19 in Switzerland among a population of 508 predominantly male soldiers with a median age of 21 years. We followed the number of infections in two spatially separated cohorts with almost identical baseline characteristics with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) before and after implementation of stringent social distancing.ResultsOf the 354 soldiers infected prior to the implementation of social distancing, 30% fell ill from COVID-19. While no soldier in a group of 154, in which infections appeared after implementation of social distancing, developed COVID-19 despite the detection of viral RNA in the nose and virus-specific antibodies within this group.ConclusionsSocial distancing not only can slow the spread of SARS-CoV-2 in a cohort of young, healthy adults but can also prevent the outbreak of COVID-19 while still inducing an immune response and colonizing nasal passages. Viral inoculum during infection or mode of transmission may be key factors determining the clinical course of COVID-19.

Pre-existing immunity to influenza virus hemagglutinin stalk might drive selection for antibody-escape mutant viruses in a human challenge model.

The conserved region of influenza hemagglutinin (HA) stalk (or stem) has gained attention as a potent target for universal influenza vaccines1-5. Although the HA stalk region is relatively well conserved, the evolutionarily dynamic nature of influenza viruses6 raises concerns about the possible emergence of viruses carrying stalk escape mutation(s) under sufficient immune pressure. Here we show that immune pressure on the HA stalk can lead to expansion of escape mutant viruses in study participants challenged with a 2009 H1N1 pandemic influenza virus inoculum containing an A388V polymorphism in the HA stalk (45% wild type and 55% mutant). High level of stalk antibody titers was associated with the selection of the mutant virus both in humans and in vitro. Although the mutant virus showed slightly decreased replication in mice, it was not observed in cell culture, ferrets or human challenge participants. The A388V mutation conferred resistance to some of the potent HA stalk broadly neutralizing monoclonal antibodies (bNAbs). Co-culture of wild-type and mutant viruses in the presence of either a bNAb or human serum resulted in rapid expansion of the mutant. These data shed light on a potential obstacle for the success of HA-stalk-targeting universal influenza vaccines-viral escape from vaccine-induced stalk immunity.

Association of a begomovirus-satellite complex with yellow vein and leaf curl disease of hollyhock (Alcea rosea) in India.

Geminiviruses cause considerable yield loss in several crop plants worldwide. In 2016, several hollyhock plants displaying yellow mosaic and leaf curling symptoms were noticed in a nursery of Jawaharlal Nehru University, New Delhi, India. Analysis of the collected samples indicated an association of monopartite and bipartite begomoviruses with satellites. Three begomoviruses (including a member of a new begomovirus species), two alphasatellites, and a betasatellite were isolated from yellow-mosaic-disease-affected plants. Similarly, a begomovirus, two alphasatellites, and a betasatellite were found to be associated with leaf curl disease of hollyhock. These begomoviruses and satellites were found to be recombinants. By harboring diverse begomoviruses and satellite DNAs, hollyhock may serve as a potential source of virus inoculum.

Inoculum at the time of SARS-CoV-2 exposure and risk of disease severity

A relationship between the infecting dose and the risk of disease severity has not been demonstrated for SARS-CoV-2 infection. Here, we report three clusters of individuals that were potentially exposed to distinct inoculum in Madrid. Overall each group developed divergent clinical forms of COVID-19. Our data support that a greater viral inoculum at the time of SARS-CoV-2 exposure might determine a higher risk of severe COVID-19.

Changes Introduced in the Open Reading Frame of Bovine Viral Diarrhea Virus During Serial Infection of Pregnant Swine

Bovine viral diarrhea virus (BVDV) is one of the most economically important viruses of cattle, but this pathogen is also able to infect pigs, camelids, and a wide range of domestic and wild ruminants. BVDV isolates circulating in animal populations are genetically and antigenically highly diverse. Acute BVDV infections in cattle cause the introduction of many substitutions in the viral genome. Serial infection of pregnant sheep with a BVDV-1b isolate of bovine origin was also associated with great numbers of substitutions. To our knowledge, genomic changes arising during BVDV infections in swine have not been investigated. The purpose of this study was to investigate the changes occurring in the open reading frame (ORF) of BVDV during serial infection of pregnant swine with a BVDV isolate of bovine origin. The BVDV-1b isolate AU526 was serially passaged in six pregnant gilts, two of which gave birth to live piglets congenitally infected with BVDV. The complete ORF sequences of 14 BVDV isolates obtained from pregnant gilts and their piglets were determined. Their analysis revealed that serial transmission of AU526 in pregnant swine resulted in many genomic changes. All isolates of porcine origin shared 32 nucleotide and 12 amino acid differences with the virus inoculum AU526. These changes were detected after a single passage in pregnant swine and were conserved during the subsequent five passages. Amino acid changes occurred primarily in genomic regions encoding the BVDV structural proteins E2 and Erns. These results suggest that BVDV infections in pregnant swine may contribute significantly to the genetic variability of BVDV and lead to the appearance of adaptive changes.

A modelling framework to assess the likely effectiveness of facemasks in combination with 'lock-down' in managing the COVID-19 pandemic.

COVID-19 is characterized by an infectious pre-symptomatic period, when newly infected individuals can unwittingly infect others. We are interested in what benefits facemasks could offer as a non-pharmaceutical intervention, especially in the settings where high-technology interventions, such as contact tracing using mobile apps or rapid case detection via molecular tests, are not sustainable. Here, we report the results of two mathematical models and show that facemask use by the public could make a major contribution to reducing the impact of the COVID-19 pandemic. Our intention is to provide a simple modelling framework to examine the dynamics of COVID-19 epidemics when facemasks are worn by the public, with or without imposed ‘lock-down’ periods. Our results are illustrated for a number of plausible values for parameter ranges describing epidemiological processes and mechanistic properties of facemasks, in the absence of current measurements for these values. We show that, when facemasks are used by the public all the time (not just from when symptoms first appear), the effective reproduction number, Re, can be decreased below 1, leading to the mitigation of epidemic spread. Under certain conditions, when lock-down periods are implemented in combination with 100% facemask use, there is vastly less disease spread, secondary and tertiary waves are flattened and the epidemic is brought under control. The effect occurs even when it is assumed that facemasks are only 50% effective at capturing exhaled virus inoculum with an equal or lower efficiency on inhalation. Facemask use by the public has been suggested to be ineffective because wearers may touch their faces more often, thus increasing the probability of contracting COVID-19. For completeness, our models show that facemask adoption provides population-level benefits, even in circumstances where wearers are placed at increased risk. At the time of writing, facemask use by the public has not been recommended in many countries, but a recommendation for wearing face-coverings has just been announced for Scotland. Even if facemask use began after the start of the first lock-down period, our results show that benefits could still accrue by reducing the risk of the occurrence of further COVID-19 waves. We examine the effects of different rates of facemask adoption without lock-down periods and show that, even at lower levels of adoption, benefits accrue to the facemask wearers. These analyses may explain why some countries, where adoption of facemask use by the public is around 100%, have experienced significantly lower rates of COVID-19 spread and associated deaths. We conclude that facemask use by the public, when used in combination with physical distancing or periods of lock-down, may provide an acceptable way of managing the COVID-19 pandemic and re-opening economic activity. These results are relevant to the developed as well as the developing world, where large numbers of people are resource poor, but fabrication of home-made, effective facemasks is possible. A key message from our analyses to aid the widespread adoption of facemasks would be: ‘my mask protects you, your mask protects me’.

COVID-19: Studying the Global Pandemic – Foreword

COVID-19: Studying the Global Pandemic – Foreword

A Practical Decontamination Framework for COVID-19 Front-line Workers Returning Home.

A Practical Decontamination Framework for COVID-19 Front-line Workers Returning Home.

Hippocampal damage and seizure severity during acute viral encephalitis are determined by the intensity of the infiltrating inflammatory monocyte response

Abstract The immunological response to CNS viral infection must balance the need for effective viral clearance with the need to preserve irreplaceable neurons. Failure to achieve this balance may result in death or severe cognitive impairment. We have observed hippocampal injury, compromised cognitive function, and seizures in C57BL/6 mice following acute infection with TMEV. We established that an initial innate immune response controlled by inflammatory monocyte infiltration into the brain is responsible for this neural injury. To better understand the pathogenic mechanisms involved in monocyte recruitment to the CNS we asked whether reducing the initial viral inoculum impacted the evolution of neural injury. We found that mice infected with standard (2×105 PFU) or low inoculum (1.25×104 PFU) TMEV exhibited a graded inflammatory response. Notably, a 16-fold reduction in viral inoculum resulted in 80% attenuation of the inflammatory monocyte response, concomitant with a 90% attenuation in acute production of CCL2 and complete abrogation of acute increases in TNFα and IL-6 in the hippocampus. Cognitive performance was preserved in low inoculum mice and seizure burden was highly attenuated. Despite the introduction of 16-times less virus, viral load in the brain was equivalent at 3 dpi between groups, indicating that the amount of replicating virus was not associated with reduced neuropathology. Our findings support a model in which the earliest host response to pathogen in the CNS shapes the size of the inflammatory response and constrains the downstream pathological sequelae.

Early IFN-I limits virus-specific immunity

Abstract Type I interferons (IFN-I) play a major role in the innate immune response. These cytokines are induced within hours of infection, conferring rapid protection before the onset of adaptive immunity. IFN-I are also critical for the priming of adaptive immune responses, but it is not clear if early antiviral restriction by IFN-I can also limit the amount of antigen available to prime the adaptive immune system. Here we demonstrate that reinforcement of IFN-I signaling early after viral immunization limits the priming of adaptive immunity, whereas blocking IFN-I signaling improves adaptive immunity and enhances subsequent host protection following viral re-infection. Paradoxically, short-term blockade of IFN-I improved the efficacy of clinically approved vaccines, such as the yellow fever virus vaccine (YFV-17D) and the smallpox virus vaccine, as well as experimental HIV vaccines in mice. Short-term blockade of IFN-I also improved immune responses following acute viral infections, such as those with Zika virus, lymphocytic choriomeningitis virus (LCMV), and vesicular stomatitis virus (VSV). This unexpected adjuvant effect of blocking early IFN-I responses was associated with a hyperacute increase in antigen availability, which could not be recapitulated by increasing the dose of the virus inoculum. The improvement of virus-specific immunity following acute IFN-I blockade was mechanistically due to an increase in antigen presentation and costimulation. These findings warrant a re-evaluation of the immunoregulatory roles of IFN-I during immune memory differentiation, which may provide a framework for rational vaccine design.

Chimeric Virus Made from crTMV RNA and the Coat Protein of Potato Leafroll Virus is Targeted to the Nucleolus and Can Infect Nicotiana benthamiana Mechanically.

A genetically engineered chimeric virus crTMV-CP-PLRV composed of the crucifer-infecting tobacco mosaic virus (crTMV) RNA and the potato leafroll virus (PLRV) coat protein (CP) was obtained by agroinfiltration of Nicotiana benthamiana with the binary vector pCambia-crTMV-CPPLRV. The significant levels of the chimeric virus enabled direct visualization of crTMV-CP-PLRV in the cell and to investigate the mechanism of the pathogenesis. Localization of the crTMV-CP-PLRV in plant cells was examined by immunoblot techniques, as well as light, and transmission electron microscopy. The chimera can transfer between vascular and nonvascular tissues. The chimeric virus inoculum is capable to infect N. benthamiana mechanically. The distinguishing feature of the chimeric virus, the RNA virus with the positive genome, was found to localize in the nucleolus. We also investigated the role of the N-terminal sequence of the PLRV P3 coat protein in the cellular localization of the virus. We believe that the gene of the PLRV CP can be substituted with genes from other challenging-to-study plant pathogens to produce other useful recombinant viruses.

Into the Deep (Sequence) of the Foot-and-Mouth Disease Virus Gene Pool: Bottlenecks and Adaptation during Infection in Naïve and Vaccinated Cattle.

Foot-and-mouth disease virus (FMDV) infects hosts as a population of closely related viruses referred to as a quasispecies. The behavior of this quasispecies has not been described in detail in natural host species. In this study, virus samples collected from vaccinated and non-vaccinated cattle up to 35 days post-experimental infection with FMDV A24-Cruzeiro were analyzed by deep-sequencing. Vaccination induced significant differences compared to viruses from non-vaccinated cattle in substitution rates, entropy, and evidence for adaptation. Genomic variation detected during early infection reflected the diversity inherited from the source virus (inoculum), whereas by 12 days post infection, dominant viruses were defined by newly acquired mutations. Mutations conferring recognized fitness gain occurred and were associated with selective sweeps. Persistent infections always included multiple FMDV subpopulations, suggesting distinct foci of infection within the nasopharyngeal mucosa. Subclinical infection in vaccinated cattle included very early bottlenecks associated with reduced diversity within virus populations. Viruses from both animal cohorts contained putative antigenic escape mutations. However, these mutations occurred during later stages of infection, at which time transmission is less likely to occur. This study improves upon previously published work by analyzing deep sequences of samples, allowing for detailed characterization of FMDV populations over time within multiple hosts.

Identification of the main virus infecting impatiens (Impatiens balsamina L.)

One of the most important obstacles of growing ornamental plants, such as impatiens is disease infections, including those caused by viruses. Identification of viruses infecting impatiens was carried out in the IOCRI Virology laboratory using serological techniques and RT-PCR. Infected plants showed different symptoms involving mosaic, mottle, malformation, and wrinkles (frizz) on the leaves. The results of serological test using 5 antisera, i.e. Impatiens necrotic spot virus (INSV), Tomato spotted wilt virus (TSWV), Cucumber mosaic virus (CMV), Turnip mosaic virus (TuMV), and Tobacco mosaic virus (TMV) on leaf samples showed negative reaction. Bioassay tests carried out using 5 different symptomatic viral inoculums showed that only 2 inoculums (no.1 and 3), i.e. those with mosaic symptoms was successfully transmitted by mechanical inoculation to Chenopodium quinoa. Virus confirmation from infected C. quinoa was carried out by RT-PCR using specific primer for INSV, TSWV, and CMV. Amplification of viral DNA target was obtained only using specific primer for CMV. Therefore, we concluded that the causal agent of mosaic symptom found on impatiens plants in Cianjur is CMV.

Intrahost cytomegalovirus population genetics following antibody pretreatment in a monkey model of congenital transmission.

Human cytomegalovirus (HCMV) infection is the leading non-genetic cause of congenital birth defects worldwide. While several studies have addressed the genetic composition of viral populations in newborns diagnosed with HCMV, little is known regarding mother-to-child viral transmission dynamics and how therapeutic interventions may impact within-host viral populations. Here, we investigate how preexisting CMV-specific antibodies shape the maternal viral population and intrauterine virus transmission. Specifically, we characterize the genetic composition of CMV populations in a monkey model of congenital CMV infection to examine the effects of passively-infused hyperimmune globulin (HIG) on viral population genetics in both maternal and fetal compartments. In this study, 11 seronegative, pregnant monkeys were challenged with rhesus CMV (RhCMV), including a group pretreated with a standard potency HIG preparation (n = 3), a group pretreated with a high-neutralizing potency HIG preparation (n = 3), and an untreated control group (n = 5). Targeted amplicon deep sequencing of RhCMV glycoprotein B and L genes revealed that one of the three strains present in the viral inoculum (UCD52) dominated maternal and fetal viral populations. We identified minor haplotypes of this strain and characterized their dynamics. Many of the identified haplotypes were consistently detected at multiple timepoints within sampled maternal tissues, as well as across tissue compartments, indicating haplotype persistence over time and transmission between maternal compartments. However, haplotype numbers and diversity levels were not appreciably different between control, standard-potency, and high-potency pretreatment groups. We found that while the presence of maternal antibodies reduced viral load and congenital infection, it had no apparent impact on intrahost viral genetic diversity at the investigated loci. Interestingly, some minor haplotypes present in fetal and maternal-fetal interface tissues were also identified as minor haplotypes in corresponding maternal tissues, providing evidence for a loose RhCMV mother-to-fetus transmission bottleneck even in the presence of preexisting antibodies.

Model Averaging in Viral Dynamic Models.

The paucity of experimental data makes both inference and prediction particularly challenging in viral dynamic models. In the presence of several candidate models, a common strategy is model selection (MS), in which models are fitted to the data but only results obtained with the "best model" are presented. However, this approach ignores model uncertainty, which may lead to inaccurate predictions. When several models provide a good fit to the data, another approach is model averaging (MA) that weights the predictions of each model according to its consistency to the data. Here, we evaluated by simulations in a nonlinear mixed-effect model framework the performances of MS and MA in two realistic cases of acute viral infection, i.e., (1) inference in the presence of poorly identifiable parameters, namely, initial viral inoculum and eclipse phase duration, (2) uncertainty on the mechanisms of action of the immune response. MS was associated in some scenarios with a large rate of false selection. This led to a coverage rate lower than the nominal coverage rate of 0.95 in the majority of cases and below 0.50 in some scenarios. In contrast, MA provided better estimation of parameter uncertainty, with coverage rates ranging from 0.72 to 0.98 and mostly comprised within the nominal coverage rate. Finally, MA provided similar predictions than those obtained with MS. In conclusion, parameter estimates obtained with MS should be taken with caution, especially when several models well describe the data. In this situation, MA has better performances and could be performed to account for model uncertainty.