Displaying publications 61 - 80 of 137 in total

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  1. Yee PTI, Tan SH, Ong KC, Tan KO, Wong KT, Hassan SS, et al.
    Sci Rep, 2019 03 18;9(1):4805.
    PMID: 30886246 DOI: 10.1038/s41598-019-41285-z
    Besides causing mild hand, foot and mouth infections, Enterovirus A71 (EV-A71) is associated with neurological complications and fatality. With concerns about rising EV-A71 virulence, there is an urgency for more effective vaccines. The live attenuated vaccine (LAV) is a more valuable vaccine as it can elicit both humoral and cellular immune responses. A miRNA-based vaccine strain (pIY) carrying let-7a and miR-124a target genes in the EV-A71 genome which has a partial deletion in the 5'NTR (∆11 bp) and G64R mutation (3Dp°l) was designed. The viral RNA copy number and viral titers of the pIY strain were significantly lower in SHSY-5Y cells that expressed both let-7a and miR-124a. Inhibition of the cognate miRNAs expressed in RD and SHSY-5Y cells demonstrated de-repression of viral mRNA translation. A previously constructed multiply mutated strain, MMS and the pIY vaccine strain were assessed in their ability to protect 4-week old mice from hind limb paralysis. The MMS showed higher amounts of IFN-γ ex vivo than the pIY vaccine strain. There was absence of EV-A71 antigen in the skeletal muscles and spinal cord micrographs of mice vaccinated with the MMS and pIY strains. The MMS and pIY strains are promising LAV candidates developed against severe EV-A71 infections.
    Matched MeSH terms: Viral Load
  2. Kim JH, Chong CK, Sinniah M, Sinnadurai J, Song HO, Park H
    J Clin Virol, 2015 Apr;65:11-9.
    PMID: 25766980 DOI: 10.1016/j.jcv.2015.01.018
    BACKGROUND: Dengue is a mosquito-borne disease that causes a public health problem in tropical and subtropical countries. Current immunological diagnostics based on IgM and/or nonstructural protein 1 (NS1) antigen are limited for acute dengue infection due to low sensitivity and accuracy.
    OBJECTIVES: This study aimed to develop a one-step multiplex real-time RT-PCR assay showing higher sensitivity and accuracy than previous approaches.
    STUDY DESIGN: Serotype-specific primers and probes were designed through the multiple alignment of NS1 gene. The linearity and limit of detection (LOD) of the assay were determined. The assay was clinically validated with an evaluation panel that was immunologically tested by WHO and Malaysian specimens.
    RESULTS: The LOD of the assay was 3.0 log10 RNA copies for DENV-1, 2.0 for DENV-3, and 1.0 for DENV-2 and DENV-4. The assay showed 95.2% sensitivity (20/21) in an evaluation panel, whereas NS1 antigen- and anti-dengue IgM-based immunological assays exhibited 0% and 23.8-47.6% sensitivities, respectively. The assay showed 100% sensitivity both in NS1 antigen- and anti-dengue IgM-positive Malaysian specimens (26/26). The assay provided the information of viral loads and serotype with discrimination of heterotypic mixed infection.
    CONCLUSIONS: The assay could be clinically applied to early dengue diagnosis, especially during the first 5 days of illness and approximately 14 days after infection showing an anti-dengue IgM-positive response.
    Matched MeSH terms: Viral Load
  3. Rasoli M, Yeap SK, Tan SW, Roohani K, Kristeen-Teo YW, Alitheen NB, et al.
    BMC Vet Res, 2015;11:75.
    PMID: 25884204 DOI: 10.1186/s12917-015-0377-x
    Very virulent infectious bursal disease virus (vvIBDV) induces immunosuppression and inflammation in young birds, which subsequently leads to high mortality. In addition, infectious bursal disease (IBD) is one of the leading causes of vaccine failure on farms. Therefore, understanding the immunopathogenesis of IBDV in both the spleen and the bursae could help effective vaccine development. However, previous studies only profiled the differential expression of a limited number of cytokines, in either the spleen or the bursae of Fabricius of IBDV-infected chickens. Thus, this study aims to evaluate the in vitro and in vivo immunoregulatory effects of vvIBDV infection on macrophage-like cells, spleen and bursae of Fabricius.
    Matched MeSH terms: Viral Load
  4. Rasoli M, Yeap SK, Tan SW, Moeini H, Ideris A, Bejo MH, et al.
    Comp Immunol Microbiol Infect Dis, 2014 Jan;37(1):11-21.
    PMID: 24225159 DOI: 10.1016/j.cimid.2013.10.003
    Newcastle disease (ND) is a highly contagious avian disease and one of the major causes of economic losses in the poultry industry. The emergence of virulent NDV genotypes and repeated outbreaks of NDV in vaccinated chickens have raised the need for fundamental studies on the virus-host interactions. In this study, the profiles of B and T lymphocytes and macrophages and differential expression of 26 immune-related genes in the spleen of specific-pathogen-free (SPF) chickens, infected with either the velogenic genotype VII NDV strain IBS002 or the genotype VIII NDV strain AF2240, were evaluated. A significant reduction in T lymphocyte population and an increase in the infiltration of IgM+ B cells and KUL01+ macrophages were detected in the infected spleens at 1, 3 and 4 days post-infection (dpi) (P<0.05). The gene expression profiles showed an up-regulation of CCLi3, CXCLi1, CXCLi2 (IL-8), IFN-γ, IL-12α, IL-18, IL-1β, IL-6, iNOS, TLR7, MHCI, IL-17F and TNFSF13B (P<0.05). However, these two genotypes showed different cytokine expression patterns and viral load. IBS002 showed higher viral load than AF2240 in spleen at 3 and 4dpi and caused a more rapid up-regulation of CXCLi2, IFN-γ, IL-12α, IL-18, IL-1β, iNOS and IL-10 at 3dpi. Meanwhile, the expression levels of CCLI3, CXCLi1, IFN-γ, IL-12α, IL-1β and iNOS genes were significantly higher in AF2240 at 4dpi. In addition, the expression levels of IL-10 were significantly higher in the IBS002-infected chickens at 3 and 4dpi. Hence, infection with velogenic genotype VII and VIII NDV induced different viral load and production of cytokines and chemokines associated with inflammatory reactions.
    Matched MeSH terms: Viral Load/genetics; Viral Load/immunology; Viral Load/veterinary
  5. Farhanah MI, Yasmin AR, Mat Isa N, Hair-Bejo M, Ideris A, Powers C, et al.
    J Gen Virol, 2018 Jan;99(1):21-35.
    PMID: 29058656 DOI: 10.1099/jgv.0.000956
    Infectious bursal disease is a highly contagious disease in the poultry industry and causes immunosuppression in chickens. Genome-wide regulations of immune response genes of inbred chickens with different genetic backgrounds, following very virulent infectious bursal disease virus (vvIBDV) infection are poorly characterized. Therefore, this study aims to analyse the bursal tissue transcriptome of six inbred chicken lines 6, 7, 15, N, O and P following infection with vvIBDV strain UK661 using strand-specific next-generation sequencing, by highlighting important genes and pathways involved in the infected chicken during peak infection at 3 days post-infection. All infected chickens succumbed to the infection without major variations among the different lines. However, based on the viral loads and bursal lesion scoring, lines P and 6 can be considered as the most susceptible lines, while lines 15 and N were regarded as the least affected lines. Transcriptome profiling of the bursa identified 4588 genes to be differentially expressed, with 2985 upregulated and 1642 downregulated genes, in which these genes were commonly or uniquely detected in all or several infected lines. Genes that were upregulated are primarily pro-inflammatory cytokines, chemokines and IFN-related. Various genes that are associated with B-cell functions and genes related to apoptosis were downregulated, together with the genes involved in p53 signalling. In conclusion, bursal transcriptome profiles of different inbred lines showed differential expressions of pro-inflammatory cytokines and chemokines, Th1 cytokines, JAK-STAT signalling genes, MAPK signalling genes, and their related pathways following vvIBDV infection.
    Matched MeSH terms: Viral Load
  6. Mohd Isa F, Ahmed Al-Haj N, Mat Isa N, Ideris A, Powers C, Oladapo O, et al.
    PMID: 31837598 DOI: 10.1016/j.cimid.2019.101399
    Among different inbred chickens' lines, we previously showed that lines P and N of Institute for Animal Health, Compton, UK are the most susceptible and the least affected lines, respectively, following infection with very virulent infectious bursal disease virus (vvIBDV). In this study, the differential expressions of 29 different immune-related genes were characterized. Although, birds from both lines succumbed to infection, line P showed greater bursal lesion scores and higher viral copy numbers compared to line N. Interestingly, line N showed greater down-regulation of B cell related genes (BLNK, TNFSF13B and CD72) compared to line P. While up-regulation of T-cell related genes (CD86 and CTLA4) and Th1 associated cytokines (IFNG, IL2, IL12A and IL15) were documented in both lines, the expression levels of these genes were different in the two lines. Meanwhile, the expression of IFN-related genes IFNB, STAT1, and IRF10, but not IRF5, were up-regulated in both lines. The expression of pro-inflammatory cytokines (IL1B, IL6, IL18, and IL17) and chemokines (CXCLi2, CCL4, CCL5 and CCR5) were up-regulated in both lines with greater increase documented in line P compared to line N. Strikingly, the expression of IL12B was detected only in line P whilst the expression of IL15RA was detected only in line N. In conclusion, the bursal immunopathology of IBDV correlates more with expression of proinflammatory response related genes and does not related to expression of B-cell related genes.
    Matched MeSH terms: Viral Load
  7. Abba Y, Hassim H, Hamzah H, Ibrahim OE, Mohd Lila MA, Noordin MM
    Microb Pathog, 2017 Mar;104:17-27.
    PMID: 28062291 DOI: 10.1016/j.micpath.2017.01.003
    Boid inclusion body disease (BIBD) is a viral disease of boid snakes believed to be caused by reptarenavirus belonging to the family Arenaviridae. Unlike most mammalian arenaviruses, the reservoir host for reptarenavirus is still unknown. In this study, the pathological responses were evaluated in a mouse model for a period of 28 days. Blood and tissue samples (lung, liver, spleen, heart, kidney and brain) were collected for evaluation of hematology, biochemistry, histopathology and oxidative enzyme levels at six time points (1, 3, 7, 14, 21 and 28 days), after viral infection (2.0 × 10(6) pfu/mL) in the infected and normal saline in the control groups. An initial increase (p Viral counts were low on days 7 and 14 but surged in both the liver and spleen on day 21 and 28. This study has shown that reptarenavirus replicates in mammalian host and induces oxidative stress. Furthermore, the resultant hematobiochemical and histopathological changes observed in infected mice were similar to what has been reported in mammarenavirus infections. This suggests that rodents may serve as potential reservoir hosts for reptarenavirus.
    Matched MeSH terms: Viral Load
  8. Simarmata D, Ng DC, Kam YW, Lee B, Sum MS, Her Z, et al.
    Sci Rep, 2016 05 16;6:26097.
    PMID: 27180811 DOI: 10.1038/srep26097
    Chikungunya fever (CHIKF) is a global infectious disease which can affect a wide range of age groups. The pathological and immunological response upon Chikungunya virus (CHIKV) infection have been reported over the last few years. However, the clinical profile and immune response upon CHIKV infection in children remain largely unknown. In this study, we analyzed the clinical and immunological response, focusing on the cytokine/chemokine profile in a CHIKV-infected pediatric cohort from Sarawak, Malaysia. Unique immune mediators triggered upon CHIKV infection were identified through meta-analysis of the immune signatures between this pediatric group and cohorts from previous outbreaks. The data generated from this study revealed that a broad spectrum of cytokines/chemokines is up-regulated in a sub-group of virus-infected children stratified according to their viremic status during hospitalization. Furthermore, different immune mediator profiles (the levels of pro-inflammatory cytokines, chemokines and growth and other factors) were observed between children and adults. This study gives an important insight to understand the immune response of CHIKV infection in children and would aid in the development of better prognostics and clinical management for children.
    Matched MeSH terms: Viral Load*
  9. Nandagopal P, Bhattacharya J, Srikrishnan AK, Goyal R, Ravichandran Swathirajan C, Patil S, et al.
    J Gen Virol, 2018 Mar;99(3):379-392.
    PMID: 29458681 DOI: 10.1099/jgv.0.001016
    Broadly neutralizing antibodies (bnAbs) have been considered to be potent therapeutic tools and potential vaccine candidates to enable protection against various clades of human immunodeficiency virus (HIV). The generation of bnAbs has been associated with enhanced exposure to antigen, high viral load and low CD4+ T cell counts, among other factors. However, only limited data are available on the generation of bnAbs in viraemic non-progressors that demonstrate moderate to high viraemia. Further, since HIV-1 subtype C viruses account for more than 50 % of global HIV infections, the identification of bnAbs with novel specificities is crucial to enable the development of potent tools to aid in HIV therapy and prevention. In the present study, we analysed and compared the neutralization potential of responses in 70 plasma samples isolated from ART-naïve HIV-1 subtype C-infected individuals with various disease progression profiles against a panel of 30 pseudoviruses. Among the seven samples that exhibited a neutralization breadth of ≥70 %, four were identified as 'elite neutralizers', and three of these were from viraemic non-progressors while the fourth was from a typical progressor. Analysis of the neutralization specificities revealed that none of the four elite neutralizers were reactive to epitopes in the membrane proximal external region (MPER), CD4-binding site and V1V2 or V3 glycan. However, two of the four elite neutralizers exhibited enhanced sensitivity towards viruses lacking N332 glycan, indicating high neutralization potency. Overall, our findings indicate that the identification of potent neutralization responses with distinct epitope specificities is possible from the as yet unexplored Indian population, which has a high prevalence of HIV-1 subtype C infection.
    Matched MeSH terms: Viral Load
  10. Vignesh R, Swathirajan CR, Solomon SS, Shankar EM, Murugavel KG
    Indian J Med Microbiol, 2017 Apr-Jun;35(2):279-281.
    PMID: 28681821 DOI: 10.4103/ijmm.IJMM_16_163
    Immune reconstitution inflammatory syndrome (IRIS) continues to be a complication in HIV/tuberculosis (TB) co-infected patients initiating highly active antiretroviral therapy (HAART). The aim of this study was to evaluate the risk factors associated with developing IRIS to identify a possible biomarker to predict or diagnose IRIS in patients initiating HAART. A total of 175 HIV/TB co-infected patients initiating HAART were followed up longitudinally during September 2010 to May 2013 attending a HIV care clinic in Chennai. Patients were followed up longitudinally after HAART initiation and baseline demographic, laboratory parameters and treatment characteristics between patients with IRIS events and those without IRIS events were compared. Chi-square or Fisher's exact test for categorical variables and a Wilcoxon rank-sum test for continuous variables were performed using SPSS, version 12.0 software. Patients with IRIS had a significantly lower median baseline CD4+ T-cell count (P = 0.0039). There were no differences in terms of sex, CD4 T-cell %, plasma viral load, time interval between initiating ATT and HAART between the IRIS and non-IRIS patients. Low CD4+ T-cell count (<100 cells/μL) could be used as a marker to screen and monitor patients initiating HAART.
    Matched MeSH terms: Viral Load
  11. Al-Alimi AA, Ali SA, Al-Hassan FM, Idris FM, Teow SY, Mohd Yusoff N
    PLoS Negl Trop Dis, 2014 Mar;8(3):e2711.
    PMID: 24625456 DOI: 10.1371/journal.pntd.0002711
    Dengue virus is endemic in peninsular Malaysia. The clinical manifestations vary depending on the incubation period of the virus as well as the immunity of the patients. Glucose-6-phosphate dehydrogenase (G6PD) deficiency is prevalent in Malaysia where the incidence is 3.2%. It has been noted that some G6PD-deficient individuals suffer from more severe clinical presentation of dengue infection. In this study, we aim to investigate the oxidative responses of DENV2-infected monocytes from G6PD-deficient individuals.
    Matched MeSH terms: Viral Load
  12. Mok L, Wynne JW, Grimley S, Shiell B, Green D, Monaghan P, et al.
    J Gen Virol, 2015 Jul;96(Pt 7):1787-94.
    PMID: 25748429 DOI: 10.1099/vir.0.000112
    In recent years, bats have been identified as a natural reservoir for a diverse range of viruses. Nelson Bay orthoreovirus (NBV) was first isolated from the heart blood of a fruit bat (Pteropus poliocephalus) in 1968. While the pathogenesis of NBV remains unknown, other related members of this group have caused acute respiratory disease in humans. Thus the potential for NBV to impact human health appears plausible. Here, to increase our knowledge of NBV, we examined the replication and infectivity of NBV using different mammalian cell lines derived from bat, human, mouse and monkey. All cell lines supported the replication of NBV; however, L929 cells showed a greater than 2 log reduction in virus titre compared with the other cell lines. Furthermore, NBV did not induce major cytopathic effects in the L929 cells, as was observed in other cell lines. Interestingly, the related Pteropine orthoreoviruses, Pulau virus (PulV) and Melaka virus (MelV) were able to replicate to high titres in L929 cells but infection resulted in reduced cytopathic effect. Our study demonstrates a unique virus-host interaction between NBV and L929 cells, where cells effectively control viral infection/replication and limit the formation of syncytia. By elucidating the molecular mechanisms that control this unique relationship, important insights will be made into the biology of this fusogenic virus.
    Matched MeSH terms: Viral Load
  13. Loeliger KB, Altice FL, Desai MM, Ciarleglio MM, Gallagher C, Meyer JP
    Lancet HIV, 2018 02;5(2):e96-e106.
    PMID: 29191440 DOI: 10.1016/S2352-3018(17)30209-6
    BACKGROUND: Incarceration provides an opportunity for engagement in HIV care but is associated with poor HIV treatment outcomes after release. We aimed to assess post-release linkage to HIV care (LTC) and the effect of transitional case management services.

    METHODS: To create a retrospective cohort of all adults with HIV released from jails and prisons in Connecticut, USA (2007-14), we linked administrative custody and pharmacy databases with mandatory HIV/AIDS surveillance monitoring and case management data. We examined time to LTC (defined as first viral load measurement after release) and viral suppression at LTC. We used generalised estimating equations to show predictors of LTC within 14 days and 30 days of release.

    FINDINGS: Among 3302 incarceration periods for 1350 individuals between 2007 and 2014, 672 (21%) of 3181 periods had LTC within 14 days of release, 1042 (34%) of 3064 had LTC within 30 days of release, and 301 (29%) of 1042 had detectable viral loads at LTC. Factors positively associated with LTC within 14 days of release are intermediate (31-364 days) incarceration duration (adjusted odds ratio 1·52; 95% CI 1·19-1·95), and transitional case management (1·65; 1·36-1·99), receipt of antiretroviral therapy during incarceration (1·39; 1·11-1·74), and two or more medical comorbidities (1·86; 1·48-2·36). Reincarceration (0·70; 0·56-0·88) and conditional release (0·62; 0·50-0·78) were negatively associated with LTC within 14 days. Hispanic ethnicity, bonded release, and psychiatric comorbidity were also associated with LTC within 30 days but reincarceration was not.

    INTERPRETATION: LTC after release is suboptimal but improves when inmates' medical, psychiatric, and case management needs are identified and addressed before release. People who are rapidly cycling through jail facilities are particularly vulnerable to missed linkage opportunities. The use of integrated programmes to align justice and health-care goals has great potential to improve long-term HIV treatment outcomes.

    FUNDING: US National Institutes of Health.

    Matched MeSH terms: Viral Load
  14. Tan SS, Abu Hassan MR, Abdullah A, Ooi BP, Korompis T, Merican MI
    J Viral Hepat, 2010 Jun;17(6):410-8.
    PMID: 19758272 DOI: 10.1111/j.1365-2893.2009.01191.x
    Chronic hepatitis C is associated with increased morbidity and mortality in persons undergoing haemodialysis. This single-arm, open-label clinical trial investigated the safety and efficacy of an escalating dosage regimen of pegylated interferon (PEG-IFN) alpha-2b in this patient population. Patients with chronic hepatitis C who were undergoing haemodialysis began treatment with PEG-IFN alpha-2b at a dose of 0.5 microg/kg/week, which was increased every 4 weeks to a maximum of 1 microg/kg/week. Treatment duration was 24 weeks for patients with genotype (G) 2 or 3 infection and 48 weeks for patients with G1 infection. The primary end point was sustained virological response (SVR). Of 46 patients screened, 34 (G1: 70.6%; G3: 29.4%) were treated and 23 (67.6%) completed treatment. Overall, 85.3% of patients experienced early virological response, 52.9% experienced end-of-treatment response, and 50% attained SVR, with a trend toward higher SVR rates in G3 compared with G1 patients (80%vs 37.5%; P = 0.06). Anaemia was the main reason for discontinuation of treatment. Patients with chronic hepatitis C who are undergoing haemodialysis can be successfully treated with an escalating dosage regimen of PEG-IFN alpha-2b monotherapy. G3-infected patients can attain high rates of SVR with only 24 weeks of therapy.
    Matched MeSH terms: Viral Load
  15. Durier N, Yunihastuti E, Ruxrungtham K, Kinh NV, Kamarulzaman A, Boettiger D, et al.
    J Viral Hepat, 2017 03;24(3):187-196.
    PMID: 27917597 DOI: 10.1111/jvh.12630
    Data on markers of hepatitis C virus (HCV) disease in HIV-HCV-coinfected patients in resource-limited settings are scarce. We assessed HCV RNA, HCV genotype (GT), IL28B GT and liver fibrosis (FibroScan® ) in 480 HIV-infected patients with positive HCV antibody in four HIV treatment centres in South-East Asia. We enrolled 165 (34.4%) patients in Jakarta, 158 (32.9%) in Bangkok, 110 (22.9%) in Hanoi and 47 (9.8%) in Kuala Lumpur. Overall, 426 (88.8%) were male, the median (IQR) age was 38.1 (34.7-42.5) years, 365 (76.0%) reported HCV exposure through injecting drug use, and 453 (94.4%) were on combination antiretroviral therapy. The median (IQR) CD4 count was 446 (325-614) cells/mm3 and 208 (94.1%) of 221 patients tested had HIV-1 RNA <400 copies/mL. A total of 412 (85.8%) had detectable HCV RNA, at a median (IQR) of 6.2 (5.4-6.6) log10 IU/mL. Among 380 patients with HCV GT, 223 (58.7%) had GT1, 97 (25.5%) had GT3, 43 (11.3%) had GT6, eight (2.1%) had GT4, two (0.5%) had GT2, and seven (1.8%) had indeterminate GT. Of 222 patients with IL28B testing, 189 (85.1%) had rs12979860 CC genotype, and 199 (89.6%) had rs8099917 TT genotype. Of 380 patients with FibroScan® , 143 (37.6%) had no/mild liver fibrosis (F0-F1), 83 (21.8%) had moderate fibrosis (F2), 74 (19.5%) had severe fibrosis (F3), and 79 (20.8%) had cirrhosis (F4). One patient (0.3%) had FibroScan® failure. In conclusion, a high proportion of HIV-HCV-coinfected patients had chronic HCV infection. HCV GT1 was predominant, and 62% of patients had liver disease warranting prompt treatment (≥F2).
    Matched MeSH terms: Viral Load
  16. Mohamed Sohaimi N, Bejo MH, Omar AR, Ideris A, Mat Isa N
    PLoS One, 2019;14(12):e0225863.
    PMID: 31891571 DOI: 10.1371/journal.pone.0225863
    Fowl adenovirus (FAdV) is the causative agent of inclusion body hepatitis (IBH) in chickens with significant economic losses due to high mortality and poor production. It was objectives of the study to attenuate and determine the molecular characteristic of FAdV isolate (UPM1137) of Malaysia passages in primary chicken embryo liver (CEL) cells. The cytopathic effect (CPE) was recorded and the present of the virus was detected by polymerase chain reaction (PCR). Nucleotide and amino acid changes were determined and a phylogenetic tree was constructed. The pathogenicity and immunogenicity of the virus at passage 35 (CEL35) with virus titre of 106.7TCID50/mL was determined in day old specific pathogen free (SPF) chicks via oral or subcutaneous route of inoculation. The study demonstrated that the FAdV isolate was successfully propagated and attenuated in CEL cells up to 35th consecutive passages (CEL35) with delayed of CPE formation within 48 to 72 post inoculation (pi) from CEL20 onwards. The virus caused typical CPE with basophilic intranuclear inclusion bodies, refractile and clumping of cells. The virus is belong to serotype 8b with substitution of amino acid at position 44, 133 and 185 in L1 loop of hexon gene and in knob of fiber gene at position 348 and 360 at CEL35. It is non-pathogenic, but immunogenic in SPF chickens. It was concluded that the FAdV isolate was successfully attenuated in CEL cells with molecular changes in major capsid proteins which affect its infectivity in cell culture and SPF chickens.
    Matched MeSH terms: Viral Load
  17. Clayton BA, Middleton D, Arkinstall R, Frazer L, Wang LF, Marsh GA
    PLoS Negl Trop Dis, 2016 06;10(6):e0004775.
    PMID: 27341030 DOI: 10.1371/journal.pntd.0004775
    Person-to-person transmission is a key feature of human Nipah virus outbreaks in Bangladesh. In contrast, in an outbreak of Nipah virus in Malaysia, people acquired infections from pigs. It is not known whether this important epidemiological difference is driven primarily by differences between NiV Bangladesh (NiV-BD) and Malaysia (NiV-MY) at a virus level, or by environmental or host factors. In a time course study, ferrets were oronasally exposed to equivalent doses of NiV-BD or NiV-MY. More rapid onset of productive infection and higher levels of virus replication in respiratory tract tissues were seen for NiV-BD compared to NiV-MY, corroborating our previous report of increased oral shedding of NiV-BD in ferrets and suggesting a contributory mechanism for increased NiV-BD transmission between people compared to NiV-MY. However, we recognize that transmission occurs within a social and environmental framework that may have an important and differentiating role in NiV transmission rates. With this in mind, ferret-to-ferret transmission of NiV-BD and NiV-MY was assessed under differing viral exposure conditions. Transmission was not identified for either virus when naïve ferrets were cohoused with experimentally-infected animals. In contrast, all naïve ferrets developed acute infection following assisted and direct exposure to oronasal fluid from animals that were shedding either NiV-BD or NiV-MY. Our findings for ferrets indicate that, although NiV-BD may be shed at higher levels than NiV-MY, transmission risk may be equivalently low under exposure conditions provided by cohabitation alone. In contrast, active transfer of infected bodily fluids consistently results in transmission, regardless of the virus strain. These observations suggest that the risk of NiV transmission is underpinned by social and environmental factors, and will have practical implications for managing transmission risk during outbreaks of human disease.
    Matched MeSH terms: Viral Load
  18. Clayton BA, Middleton D, Bergfeld J, Haining J, Arkinstall R, Wang L, et al.
    Emerg Infect Dis, 2012 Dec;18(12):1983-93.
    PMID: 23171621 DOI: 10.3201/eid1812.120875
    Human infections with Nipah virus in Malaysia and Bangladesh are associated with markedly different patterns of transmission and pathogenicity. To compare the 2 strains, we conducted an in vivo study in which 2 groups of ferrets were oronasally exposed to either the Malaysia or Bangladesh strain of Nipah virus. Viral shedding and tissue tropism were compared between the 2 groups. Over the course of infection, significantly higher levels of viral RNA were recovered from oral secretions of ferrets infected with the Bangladesh strain. Higher levels of oral shedding of the Bangladesh strain of Nipah virus might be a key factor in onward transmission in outbreaks among humans.
    Matched MeSH terms: Viral Load
  19. Mawaddah A, Gendeh HS, Lum SG, Marina MB
    Malays J Pathol, 2020 Apr;42(1):23-35.
    PMID: 32342928
    INTRODUCTION: To review the present literature on upper respiratory tract sampling in COVID-19 and provide recommendations to improve healthcare practices and directions in future studies.

    METHODS: Twelve relevant manuscripts were sourced from a total of 7288 search results obtained using PubMed, Medline and Google Scholar. The search keywords used were COVID-19, nasopharyngeal, oropharyngeal, swabs, SARS and CoV2. Original manuscripts were obtained and analysed by all authors. The review included manuscripts which have not undergone rigorous peer-review process in view of the magnitude of the topic discussed.

    RESULTS: The viral load of SARS-CoV-2 RNA in the upper respiratory tract was significantly higher during the first week and peaked at 4-6 days after onset of symptoms, during which it can be potentially sampled. Nasopharyngeal swab has demonstrated higher viral load than oropharyngeal swab, where the difference in paired samples is best seen at 0-9 days after the onset of illness. Sensitivity of nasopharyngeal swab was higher than oropharyngeal swabs in COVID-19 patients. Patient self-collected throat washing has been shown to contain higher viral load than nasopharyngeal or oropharyngeal swab, with significantly higher sensitivity when compared with paired nasopharyngeal swab.

    RECOMMENDATIONS: Routine nasopharyngeal swab of suspected COVID-19 infection should take anatomy of the nasal cavity into consideration to increase patient comfort and diagnostic yield. Routine oropharyngeal swab should be replaced by throat washing which has demonstrated better diagnostic accuracy, and it is safe towards others.

    Matched MeSH terms: Viral Load
  20. Dietzel E, Kolesnikova L, Sawatsky B, Heiner A, Weis M, Kobinger GP, et al.
    J Virol, 2016 Mar;90(5):2514-22.
    PMID: 26676785 DOI: 10.1128/JVI.02920-15
    Nipah virus (NiV) causes fatal encephalitic infections in humans. To characterize the role of the matrix (M) protein in the viral life cycle, we generated a reverse genetics system based on NiV strain Malaysia. Using an enhanced green fluorescent protein (eGFP)-expressing M protein-deleted NiV, we observed a slightly increased cell-cell fusion, slow replication kinetics, and significantly reduced peak titers compared to the parental virus. While increased amounts of viral proteins were found in the supernatant of cells infected with M-deleted NiV, the infectivity-to-particle ratio was more than 100-fold reduced, and the particles were less thermostable and of more irregular morphology. Taken together, our data demonstrate that the M protein is not absolutely required for the production of cell-free NiV but is necessary for proper assembly and release of stable infectious NiV particles.
    Matched MeSH terms: Viral Load
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