Large Amounts Of Virus Research Articles

Patient visit behaviour shapes the virus infection dynamics in hosts

Chronic HBV infection is a dynamic process of rapid viral replication and clearance, with large amounts of virus being produced and lost in the body daily. The patient's visit behaviour is closely related to viral load in the body, while the data-driven mathematical model still lacking. Therefore, we first include 28,912 patients to investigate the relationships between the visit behaviour and the HBV-DNA virus load. Then, we propose an HBV virus infection dynamics model that considers the patient's visit behaviour. The system is chaotic once the behaviour of patients during visits depends on the virus load. Our results may help us understand the process of viral transmission, and increasing the visit probability to the clinic can lead to stabilising HBV-DNA viral loads and further help healthcare professionals develop targeted clinical intervention strategies.

A Bistable Switch in HIV Disease Outcome for Antibody Treatment Following the Onset of Recurrent Aphthous Oral Ulcers

When challenged with foreign macromolecules, the humoral immune system produces an efficient response of antibody production (Skerra, 2003). However, the human immunodeficiency virus (HIV) evades CD4 T helper cells, the central component of generating neutralizing antibodies that orchestrate specific responses to a wide range of viruses (Wodarz & Nowak, 2002). When understanding the dynamic between HIV pathogenesis and immune system response, verbal reasoning proves insufficient because of the inherent complexity of the interactions involved. In particular, verbal reasoning may overlook subtle nuances, intricate feedback loops, and nonlinear relationships that are fundamental to comprehending the progression of HIV infection and the host immune response. Thus, mathematical models have proven useful in understanding how virus-antibody dynamics alter the course of HIV infection by capturing a set of assumptions and deducing logical conclusions through altering key parameters. Many studies have utilized chimeric simian-human immunodeficiency virus (SHIV) as a comparable animal model for HIV pathogenesis (Ciupe et al., 2018). It has been found that broadly neutralizing monoclonal antibodies (bnMAbs) have exceptional in vitro potency against a high-dosage mucosal HIV challenge, but the strength of protection in both high-dose and low-dose challenges is dependent upon the ratio between concentration of bnMAbs and size of the viral challenge (Moldt et al., 2012; Hessell et al., 2009). In simpler terms, the effectiveness of vaccines relies heavily on the balance between the amount and strength of antibodies produced by the immune system and the size of the virus challenge; if there are not enough strong antibodies to fight off a large amount of virus, the vaccine may not be as effective. Therefore, understanding the concentration and avidity of antibodies in relation to the size of viral inoculum proves important in developing vaccines that offer robust protection against HIV.

Performance of 22 Rapid Lateral Flow Tests for SARS-CoV-2 Antigen Detection and Influence of "Variants of Concern": Implications for Clinical Use.

ABSTRACTLarge-scale head-to-head assessment of the performance of lateral-flow tests (LFTs) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen is required in the context of the continuous emergence of new viral variants. The aim of this study was to evaluate the performance of 22 rapid LFTs for the detection of SARS-CoV-2 antigens. The clinical performance of 22 LFTs was evaluated in 1,157 samples collected in the Greater Paris area. The 8 best-performing LFTs were further assessed for their ability to detect 4 variants of concern (VOC), including the alpha, beta, delta, and omicron (BA.1) variants. The specificity of SARS-CoV-2 LFTs was generally high (100% for 15 of them) but was insufficient (<75%) for 3 tests. Sensitivity of the LFTs varied from 30.0% to 79.7% compared to nucleic acid amplification testing (NAAT). Using a cycle threshold (CT) cutoff of ≤25, sensitivity of the assays ranged from 59.7% to 100%. The 8 best-performing assays had a sensitivity of ≥80% for the detection of the 4 VOC when the CT was ≤25. Falsely negative SARS-CoV-2 antigen LFT results were observed with omicron, due to the occurrence of low viral loads (CT > 30 in 32% of samples) during the two first days following symptom onset. Several LFTs exhibited satisfactory sensitivity and specificity, whereas a few others yielded an unacceptable proportion of false-positive results and/or lacked sensitivity. The sensitivity of the best-performing assays was not influenced by VOC, including alpha, beta, delta, and omicron variants. The ability of LFTs to detect the omicron variant could be reduced during the first days following symptom onset due to lower viral loads than with other variants.IMPORTANCE The use of lateral-flow tests (LFTs) to detect SARS-CoV-2 has expanded worldwide. LFTs detect SARS-CoV-2 viral antigen and are less sensitive than nucleic acid amplification testing (NAAT). Their performance must be evaluated independently of the manufacturers. Our study assessed the performance of 22 SARS-CoV-2 antigen LFTs in large panels of well-characterized samples. The majority of LFTs tested exhibited satisfactory sensitivity and specificity, while some assays yielded unacceptable proportions of false-positive results, and others lacked sensitivity for samples containing large amounts of virus. The sensitivity of the best-performing assays did not vary according to the VOC, including the alpha, beta, delta, and omicron variants.

Particle-based analysis elucidates the real retention capacities of virus filters and enables optimal virus clearance study design with evaluation systems of diverse virological characteristics.

In virus clearance study (VCS) design, the amount of virus loaded onto the virus filters (VF) must be carefully controlled. A large amount of virus is required to demonstrate sufficient virus removal capability; however, too high a viral load causes virus breakthrough and reduces log reduction values. We have seen marked variation in the virus removal performance for VFs even with identical VCS design. Understanding how identical virus infectivity, materials and operating conditions can yield such different results is key to optimizing VCS design. The present study developed a particle number‐based method for VCS and investigated the effects on VF performance of discrepancies between apparent virus amount and total particle number of minute virus of mice. Co‐spiking of empty and genome‐containing particles resulted in a decrease in the virus removal performance proportional to the co‐spike ratio. This suggests that empty particles are captured in the same way as genome‐containing particles, competing for retention capacity. In addition, between virus titration methods with about 2.0 Log10 difference in particle‐to‐infectivity ratios, there was a 20‐fold decrease in virus retention capacity limiting the throughput that maintains the required LRV (e.g., 4.0), calculated using infectivity titers. These findings suggest that ignoring virus particle number in VCS design can cause virus overloading and accelerate filter breakthrough. This article asserts the importance of focusing on virus particle number and discusses optimization of VCS design that is unaffected by virological characteristics of evaluation systems and adequately reflect the VF retention capacity.

Characterization of antibody response in patients with acute and chronic chikungunya virus disease

BackgroundChikungunya virus (CHIKV) is a re-emerging arbovirus capable of causing chronic arthralgia, which can last for months to years. Although neutralizing antibodies have been shown to be important for viral clearance, is it not clear whether the quantitative and qualitative nature of antibodies play a role in progression to chronic disease. ObjectivesTo characterize and compare the antibody responses in acute and chronic patients in a prospective observational CHIKV study in Curaçao during the 2014-2015 outbreak. Study designWe performed virus neutralization tests and ELISA on plasma samples collected from a prospective observational chikungunya study in Curaçao to compare the complement-dependent and –independent neutralization capacity, as well as the antibody avidity index of acute and chronic patients. ResultsWe found that there was no significant difference in the virus neutralization titers between patients with acute and chronic chikungunya infection. Furthermore, we found that complement increased the neutralization capacity when large amounts of virus was used. Moreover, we found that patients with acute chikungunya disease had a significantly higher antibody avidity index compared to those with chronic disease. ConclusionsThis study suggests that virus neutralization titers in late convalescent sera do not play a role in chronic chikungunya. However, the median antibody avidity was lower in these patients and may therefore suggest a role for antibody avidity in the development of chronic disease.

Evaluation of combined inactivated vaccines against avian influenza subtypes [H5N1, H9N2] and avian infectious Bronchitis in chicken using montanide and paraffin oil adjuvants

The goal of the presented work was to prepare and evaluate physical characters andimmunogenicity of a combined inactivated Avian Influenza Virus (AIV) H5N1, H9N2 subtypes andInfectious Bronchitis Virus (IBV), strain D-88 oil emulsion vaccines. The prepared vaccines weresterile and safe. Also, they were ensured to be water in oil (W/O) emulsions using drop test,conductivity (zero mS/cm). Particle size were 950 nm and 1050 nm and dynamic viscosities were19.52 Mpa.s and 39.65 Mpa.s for the vaccine with Montanide™ ISA 71 RVG adjuvant and thevaccine with paraffin oil adjuvant, respectively. They showed stability for 24 months at 4 °C withno separation. Combined inactivated oil emulsion vaccines induced cellular and humoral immuneresponses in vaccinated chicks. The vaccine with Montanide™ ISA 71-RVG adjuvant provided100% protection percent for AIV H5N1 without shedding of AIV H9N2 and IBV in comparison tothe combined vaccine with paraffin oil adjuvant that gave 84% protection percent for AIV H5N1and shedding of AIV H9N2 and IBV occurred 6th day post challenge. Montanide™ 71-RVGadjuvant has the flexible ratio of oil and antigenic media in the vaccine (60:40) allowed using largeamount of virus that showed good impact on its immunogenicity, over the paraffin oil adjuvantwhich has restricted ratio of oil and antigenic media of the vaccine (73:27).

Hepatitis E virus seroprevalence among the general population in a livestock-dense area in the Netherlands: a cross-sectional population-based serological survey

BackgroundRecent serological studies indicate that hepatitis E virus (HEV) is endemic in industrialised countries. The increasing trend in the number of autochthonous cases of HEV genotype 3 in Western European countries, stresses the importance to get insight in the exact routes of exposure. Pigs are the main animal reservoir, and zoonotic food-borne transmission of HEV is proven. However, infected pigs can excrete large amounts of virus via their faeces enabling environmental transmission of HEV to humans. This might pose a risk for of neighbouring residents of livestock farming.MethodsWithin a large study on the health of people living in the vicinity of livestock farming we performed a cross-sectional population-based serological survey among 2,494 non-farming adults from the general population in a livestock-dense area in the south of the Netherlands. Participants completed risk factor questionnaires and blood samples of 2,422 subjects (median age 58 years, range 20–72) were tested for anti-HEV IgG using an enzyme immune assay (Wantai). The aim of this study was to determine the HEV seroprevalence and to assess whether seropositivity in adults was associated with living in the vicinity of pig farms.ResultsThe average seroprevalence of HEV was 28.7% (95% CI: 26.9–30.5). Determinants associated with an increased risk for HEV seropositivity were male gender and low level of education. There was a clear trend of increasing prevalence with increasing age (Chi-square test for linear trend, X2 = 83.1; p < 0.001). A high number of pigs within 1,000 m of the residential address was not a risk factor for seropositivity.ConclusionsThis study confirmed the high HEV seroprevalence (29%) in the general population of the Netherlands, but presence of antibodies was not associated with residential proximity to pig farms. The prevalence increased with age from 10% in adolescents to 33% among those aged 50 and above, supporting the assumption of a cumulative lifetime exposure to HEV in the Netherlands as well as a higher infection pressure in the past. Our findings cannot refute the assumption that transmission is primarily food-borne.

Efficient replication and shedding of MERS CoV from the upper respiratory tract of experimentally infected dromedary camels

The Middle East respiratory syndrome coronavirus (MERS CoV) is a novel coronavirus first recognized in 2012 and is associated with severe respiratory disease in humans. Virus has been isolated from dromedary camels in endemic areas, and many camels also have neutralizing antibodies against the virus, suggesting that they are likely a reservoir host. In order to better understand the role of camels in virus transmission we experimentally infected 3 adult, male dromedary camels with a human isolate of MERS CoV. All animals developed a transient, upper respiratory tract infection associated with very minor clinical disease. Large quantities of infectious virus were isolated from nasal secretions from each animal through 7 days post-inoculation, and viral RNA was detected much longer. Although our study design was limited to 3 animals, these data indicate that MERS CoV readily infects camels, which shed large amounts of virus and likely can efficiently transmit virus to other camels and humans.

The Bicolored White-Toothed Shrew Crocidura leucodon (HERMANN 1780) Is an Indigenous Host of Mammalian Borna Disease Virus

Borna disease (BD) is a sporadic neurologic disease of horses and sheep caused by mammalian Borna disease virus (BDV). Its unique epidemiological features include: limited occurrence in certain endemic regions of central Europe, yearly varying disease peaks, and a seasonal pattern with higher disease frequencies in spring and a disease nadir in autumn. It is most probably not directly transmitted between horses and sheep. All these features led to the assumption that an indigenous virus reservoir of BDV other than horses and sheep may exist. The search for such a reservoir had been unsuccessful until a few years ago five BDV-infected shrews were found in a BD-endemic area in Switzerland. So far, these data lacked further confirmation. We therefore initiated a study in shrews in endemic areas of Germany. Within five years 107 shrews of five different species were collected. BDV infections were identified in 14 individuals of the species bicolored white-toothed shrew (Crocidura leucodon, HERMANN 1780), all originating from BD-endemic territories. Immunohistological analysis showed widespread distribution of BDV antigen both in the nervous system and in epithelial and mesenchymal tissues without pathological alterations. Large amounts of virus, demonstrated by presence of viral antigen in epithelial cells of the oral cavity and in keratinocytes of the skin, may be a source of infection for natural and spill-over hosts. Genetic analyses reflected a close relationship of the BDV sequences obtained from the shrews with the regional BDV cluster. At one location a high percentage of BDV-positive shrews was identified in four consecutive years, which points towards a self-sustaining infection cycle in bicolored white-toothed shrews. Analyses of behavioral and population features of this shrew species revealed that the bicolored white-toothed shrew may indeed play an important role as an indigenous host of BDV.

Stochastic Model for Langerhans Cells and HIV Dynamics In Vivo

Many aspects of the complex interaction between HIV and the human immune system remain elusive. Our objective is to study these interactions, focusing on the specific roles of Langerhans cells (LCs) in HIV infection. In patients infected with HIV, a large amount of virus is associated with LCs in lymphoid tissue. To assess the influence of LCs on HIV viral dynamics during antiretroviral therapy, we present and analyse a stochastic model describing the dynamics of HIV, CD4+ T cells, and LCs interactions under therapeutic intervention in vivo and show that LCs play an important role in enhancing and spreading initial HIV infection. We perform sensitivity analyses on the model to determine which parameters and/or which interaction mechanisms strongly affect infection dynamics.

Immunity to Bovine Herpesvirus 1: I. Viral lifecycle and innate immunity

Bovine herpesvirus 1 (BHV-1) causes a variety of diseases and is globally distributed. It infects via mucosal epithelium, leading to rapid lytic replication and latent infection, primarily in sensory ganglia. Large amounts of virus can be excreted by the host on primary infection or upon recrudescence of latent infection, resulting in disease spread. The bovine immune response to BHV-1 is rapid, robust, balanced, and long-lasting. The innate immune system is the first to respond to the infection, with type I interferons (IFNs), inflammatory cytokines, killing of infected host cells, and priming of a balanced adaptive immune response. The virus possesses a variety of immune evasion strategies, including inhibition of type I IFN production, chemokine and complement binding, infection of macrophages and neutrophils, and latency. BHV-1 immune suppression contributes to the severity of its disease manifestations and to the bovine respiratory disease complex, the leading cause of cattle death loss in the USA.

Stochastic Model for Langerhans Cells and HIV Dynamics in Vivo

Many aspects of the complex interaction between HIV and the human immune system remain elusive. Our objective is to study these interactions, focusing on the specific roles of langerhans cells (LCs) in HIV infection. In patients infected with HIV, a large amount of virus is associated with LCs in lymphoid tissue. To assess the influence of LCs on HIV viral dynamics during anti-retroviral therapy, we present and analyse a stochastic model describing the dynamics of HIV, CD4 T-cells, and LCs interactions under therapeutic intervention in vivo. We perform sensitivity analyses on the model to determine which parameters and/or which interaction mechanisms strongly affect infection dynamics.

Virological Evidence Supporting the Use of Raltegravir in HIV Post-Exposure Prophylaxis Regimens

The goal of post-exposure prophylaxis (PEP) for HIV is to prevent the establishment of a persistent infection following exposure to the virus. Integrase inhibitors have several potential advantages in PEP regimens, including the capacity to inhibit integration of HIV genomes that have already proceeded through reverse transcription, thereby becoming refractory to reverse transcriptase inhibitors. We sought to determine if integrase inhibitors extend the window of time during which PEP intervention might be successful. Primary costimulated CD4(+) T-cells or macrophages were infected with a luciferase-bearing HIV reporter virus, permitting sensitive detection of viral gene expression under different drug treatment conditions. Relevant antiretroviral agents were added at various pre- or post-infection time points. We showed that raltegravir effectively blocks HIV infection, even when cells are challenged with a large amount of virus. We also demonstrated that during infection of both primary costimulated CD4(+) T-cells and primary macrophages, raltegravir can inhibit infection when added at later post-infection time points than the reverse transcriptase inhibitor efavirenz. This longer post-infection efficacy window, coupled with favourable pharmacokinetic properties and low toxicity, suggest that raltegravir may prove useful in HIV PEP.

Validation of high throughput methods for tissue disruption and nucleic acid extraction for ranaviruses (family Iridoviridae)

Viruses in the family Iridoviridae cause severe disease and economic loss in a wide range of cultured, wild and ornamental fish species in many countries, justifying the development and validation of diagnostic tests. In an effort to improve the efficiency of test protocols, in this study manual and high throughput semi-automated methods for tissue homogenisation and nucleic acid purification were compared for the detection of Epizootic Haematopoeitic Necrosis Virus (EHNV). The effectiveness of these methods at releasing EHNV particles and obtaining DNA was evaluated by virus isolation in bluegill fry (BF-2) cells, enzyme-linked immunosorbent assay (ELISA) and quantitative polymerase chain reaction (qPCR). Samples were prepared using tissue from infected redfin perch (Perca fluviatilis). Antigen and DNA yield were greater after homogenisation by bead-beating than by manual grinding of tissues from experimentally infected fish, which contained low quantities of virus. Bead-beating was compatible with virus isolation. There was no difference between the manual and semi-automated methods using samples from naturally infected fish which contained large amounts of virus. There was no difference in DNA yield between manual and semi-automated nucleic acid extraction for experimentally infected fish, however nucleic acid yields were greater after manual extraction for samples from naturally infected fish. Semi-automated tissue homogenisation and nucleic acid extraction required the least amount of time and were the most cost effective. The results of this study can be used as a guide to the selection of sample preparation procedures for other ranaviruses and probably more widely.

Breda and Breda-like viruses: diagnosis, pathology and epidemiology.

Breda virus serotype 1 (Iowa) was isolated from a severe outbreak of neonatal calf diarrhoea in which 15% of the diarrhoeic animals died. Two further isolates, one from Iowa and one from Ohio, are antigenically related to the first isolate but belong to the Breda virus serotype 2 group by haemagglutination inhibition and by immuno-electron microscopy (IEM). The majority (88.5%) of cattle are serologically positive for Breda virus by enzyme-linked immunosorbent assay (ELISA). The diagnostic methods of choice should include a combination of electron microscopy, IEM, haemagglutination inhibition or ELISA, in order to identify all serotypes of Breda virus. Serotypes 1 and 2 infect and replicate in crypt and epithelial cells of the small intestine, from the mid jejunum region posteriorly through to the descending colon. Virus replicates in and is released from cells before the appearance of microscopic lesions and clinical signs. Diarrhoea starts within 24-72 hours of infection and death can occur within 36-48 hours after the onset of diarrhoea. The morphology of Breda virus, determined by negative staining and from ultrastructural studies of infected cells, is unique and probably diagnostic. Little is known about the epidemiology, other than that transmission is faecal-orally and may require close contact. Large quantities of virus are released in the faeces.

The use of monoreassortants and reverse genetics to map reovirus lysis of a ras-transformed cell line

Reovirus has been shown to lyse most transformed cells while establishing a persistent or abortive infection in non-transformed cells. Developing methods to identify the reovirus genes associated with oncolysis is an important step toward understanding the mechanisms involved. This report is the first to develop and apply the use of monoreassortants and reverse genetics to identify an individual reovirus gene associated with reovirus oncolysis. Infection with reovirus serotypes 1/Lang, 2/Jones or 3/Dearing of cells transformed with a normal copy of c-Ha-RAS (N1 cells) or with a normal copy of c-Myc (Myc-3 cells), produces large amounts of progeny virus of all three serotypes and results in lysis of both these cell lines. Infection of cells transformed with a mutant c-Ha-RAS gene (T1 cells) with either serotype 1/Lang and 2/Jones results in the production of large amounts of virus and lysis of the cells. In sharp contrast, serotype 3/Dearing virus infection of these cells produced small amounts of virus and resulted in limited lysis of these cells. Using monoreassortants and reverse genetics we exploited this phenotypic difference between the three serotypes to identify a single reovirus gene linked to the preferential lysis of the T1 cells, the S4 gene.

Expresión de antígenos del virus de la fiebre aftosa en plantas transgénicas

Owing to its geographical distribution and its highly contagious character, the foot and mouth disease (FMD) virus is responsible for one of the most dreaded of all livestock diseases. The currently-used vaccine is polyvalent and is based on an inactivated virus. Current research on FMD vaccines focuses on the creation of vaccines that are easier and cheaper to produce, and that avoid manipulation of large quantities of virus. The use of transgenic plants to express relevant antigens has been evaluated for the purpose of vaccine production. The authors' working group has taken the FMD virus as a model to evaluate the feasibility of using transgenic plants to express viral antigens and to develop experimental vaccines. The purpose of this paper is to set forth the working group's results in the expression of FMD antigens in transgenic plants.

Interactions between Natural Killer Cells and Antibody Fc Result in Enhanced Antibody Neutralization of Human Immunodeficiency Virus Type 1

Antibodies can prevent lentivirus infections in animals and may play a role in controlling viral burden in established infection. In preventing and particularly in controlling infection, antibodies likely function in the presence of large quantities of virus. In this study, we explored the mechanisms by which antibodies neutralize large inocula of human immunodeficiency virus type 1 (HIV-1) on different target cells. Immunoglobulin G (IgG) from HIV-infected patients was tested for neutralizing activity against primary R5 strains of HIV-1 at inocula ranging from 100 to 20,000 50% tissue culture infective doses. At all virus inocula, inhibition by antibody was enhanced when target cells for virus growth were monocyte-depleted, peripheral blood mononuclear cells (PBMCs) rather than CD4(+) lymphocytes. However, enhanced inhibition on PBMCs was greatest with larger amounts of virus. Depleting PBMCs of natural killer (NK) cells, which express Fc receptors for IgG (FcgammaRs), abrogated the enhanced antibody inhibition, whereas adding NK cells to CD4(+) lymphocytes restored inhibition. There was no enhanced inhibition on PBMCs when F(ab')(2) was used. Further experiments demonstrated that the release of beta-chemokines, most likely through FcgammaR triggering of NK cells, contributed modestly to the antiviral activity of antibody on PBMCs and that antibody-coated virus adsorbed to uninfected cells provided a target for NK cell-mediated inhibition of HIV-1. These results indicate that Fc-FcgammaR interactions enhance the ability of antibody to neutralize HIV-1. Since FcgammaR-bearing cells are always present in vivo, FcgammaR-mediated antibody function may play a role in the ability of antibody to control lentivirus infection.

Pediatric Cough and Cold Preparations

Pediatric Cough and Cold Preparations

Pathology and ultrastructure of Hz-2V infection in the agonadal female corn earworm, Helicoverpa zea.

The pathology and ultrastructure of the reproductive tract of Hz-2V-infected female corn earworm moths, Helicoverpa zea, were studied. The identity of malformed reproductive tissues found in virus-infected moths was determined by examining these tissues in moths that were infected with the virus at different life stages. Malformation of reproductive tissues in the progeny of virus-infected female moths was first observed by 3 days post-pupation (dpp), indicating that virus replication had altered the differentiation of these tissues very early on in their development. The ultrastructure of the grossly malformed agonadal reproductive tissues from insects aged 3-10dpp revealed the absence of the cuticular lining found in the oviducts of normal moths, and the proliferation of epithelial cells in these infected oviduct tissues. In addition, large quantities of virus were found aggregated into a large mass in the lumen of the malformed cervix bursa of 10dpp agonadal female pharate adult moths. Prior to eclosion, the virus in the cervix bursa was observed separated into spherical masses, which are thought to exude through the ductus bursa and collect over the vulva, forming a viral "waxy plug" that is likely to play an important role in virus transmission.