Experimental infection of tick cells with Nipah virus

@#Nipah virus (NiV), a highly pathogenic henipavirus of the family Paramyxoviridae, which causes fatal encephalitis in 40-70% of affected patients, was first reported in Malaysia over 20 years ago. Pteropid bats are the natural hosts of henipaviruses, and ticks have been proposed as a possible link between bats and mammalian hosts. To investigate this hypothesis, infection of the tick cell line IDE8 with NiV was examined. Presence of viral RNA and antigen in the NiV-infected tick cells was confirmed. Infectious virions were recovered from NiV-infected tick cells and ultrastructural features of NiV were observed by electron microscopy. These results suggest that ticks could support NiV infection, potentially playing a role in transmission.

Visual Detection of Plant Viral RNA Based on Gold Nanoparticles and Hybrid Chain Reaction / 中国生物化学与分子生物学报

The harm of plant virus disease is serious, which significantly restricts the sustainable development of agriculture and can cause huge economic losses. Monitoring plant health and early detection of viral pathogens are essential to reduce the spread of disease. Therefore, in order to realize the early detection of plant viral diseases in the field, a sensitive, specific and efficient colorimetric visual technique for plant viral RNA was designed by combining the colorimetric method based on gold nanoparticles (AuNPs) and hybrid chain reaction (HCR). In this study, tobacco mosaic virus (TMV) was used as a model to design two hairpin structures H1/ H2 with single-stranded tails based on TMV-specific conserved fragments. TMV could open the hairpin structure to alternately form long double-straight DNA. The binding difference between AuNPs and two nucleic acid states before and after HCR reaction resulted in colorimetric signal generation, thus realizing visual detection of TMV. After optimizing the concentration of Tris-HAc, the concentration of hairpin structure and the reaction time of HCR, the best detection conditions were obtained. The sensitivity and specificity of the technique were analyzed and real samples were tested under optimal conditions. The results showed that the absorbance ratio of AuNPs (A

Coronavirus persistence in human respiratory tract and cell culture: An overview

ABSTRACT Emerging human coronaviruses, including the recently identified SARS-CoV-2, are relevant respiratory pathogens due to their potential to cause epidemics with high case fatality rates, although endemic coronaviruses are also important for immunocompromised patients. Long-term coronavirus infections had been described mainly in experimental models, but it is currently evident that SARS-CoV-2 genomic-RNA can persist for many weeks in the respiratory tract of some individuals clinically recovered from coronavirus infectious disease-19 (COVID-19), despite a lack of isolation of infectious virus. It is still not clear whether persistence of such viral RNA may be pathogenic for the host and related to long-term sequelae. In this review, we summarize evidence of SARS-CoV-2 RNA persistence in respiratory samples besides results obtained from cell culture and histopathology describing long-term coronavirus infection. We also comment on potential mechanisms of coronavirus persistence and relevance for pathogenesis.

SARS-CoV-2 nucleic acid shedding is variable for every person

Abstract INTRODUCTION: Considering the persistent positivity on RT-qPCR tests, the results of SARS-CoV-2 were monitored to evaluate the viral RNA shedding period. METHODS: Between March and June 2020, the sequential results of 29 healthcare workers' were monitored using RT-qPCR. RESULTS: More than 50% of the individuals remained RT-qPCR positive after 14 days. Furthermore, this is the first study to describe positive RT-qPCR for SARS-CoV-2 in a healthcare worker with mild symptoms 95 days after the first positive test. CONCLUSIONS: Sequential RT-qPCR results were heterogeneous, and the viral RNA shedding period is unique for each person.

Mutations in SARS-CoV-2 viral RNA identified in Eastern India: Possible implications for the ongoing outbreak in India and impact on viral structure and host susceptibility

Direct massively parallel sequencing of SARS-CoV-2 genome was undertaken from nasopharyngeal andoropharyngeal swab samples of infected individuals in Eastern India. Seven of the isolates belonged to the A2aclade, while one belonged to the B4 clade. Specific mutations, characteristic of the A2a clade, were alsodetected, which included the P323L in RNA-dependent RNA polymerase and D614G in the Spike glycoprotein. Further, our data revealed emergence of novel subclones harbouring nonsynonymous mutations, viz.G1124V in Spike (S) protein, R203K, and G204R in the nucleocapsid (N) protein. The N protein mutationsreside in the SR-rich region involved in viral capsid formation and the S protein mutation is in the S2 domain,which is involved in triggering viral fusion with the host cell membrane. Interesting correlation was observedbetween these mutations and travel or contact history of COVID-19 positive cases. Consequent alterations ofmiRNA binding and structure were also predicted for these mutations. More importantly, the possibleimplications of mutation D614G (in SD domain) and G1124V (in S2 subunit) on the structural stability of Sprotein have also been discussed. Results report for the first time a bird’s eye view on the accumulation ofmutations in SARS-CoV-2 genome in Eastern India.

Vacunas para SARS-CoV-2: diferentes estrategias de los desarrollos en curso / Vaccines for SARS-CoV-2: different strategies of ongoing developments

El objetivo de este artículo es proporcionar una guía que sirva para la interpretación y seguimiento de los esfuerzos que se están desarrollando en todo el mundo con el objetivo de obtener una vacuna que pueda generar inmunidad contra el nuevo coronavirus SARS-CoV-2 de 2019, el agente causante de la enfermedad por coronavirus denominada COVID-19. Cinco meses después de haber sido detectada la enfermedad, ya hay 102 vacunas en distintos estadios de desarrollo, registradas por la Organización Mundial de la Salud (OMS), correspondientes a 8 plataformas vacunales con diferentes estrategias, y todos los días aparecen nuevas. Esto representará un enorme desafío de organismos internacionales, para la evaluación, comparación y selección de aquellas que cumplan con los criterios regulatorios indispensables de seguridad y eficacia y que, por otro lado, puedan ser producidas en cantidades suficientes para abastecer la demanda mundial. (AU)

The objective of this article is to provide a guide to help the interpretation and monitoring the efforts that are being carried out worldwide to obtain a vaccine that will be able to generate immunity against the new 2019 SARS-CoV-2 coronavirus, the viral agent causes the disease named COVID-19. Five months after the disease was detected, there are already 102 vaccines at different stages of development, registered by World Health Organization (WHO), corresponding to 8 vaccination platforms base on different strategies, and every day new ones appear. This will represent a huge challenge for international organizations, to evaluate, compare and selects those that will meet the essential regulatory criteria of safety and efficacy and that, would be able to be produced in enough quantities to supply the worldwide demand. Key words: SARS-Cov-2 vaccine, vaccine platform, COVID-19 strategy, attenuated virus, viral vector, viral proteins, viral DNA, viral RNA, nucleic acids, viral like particles, WHO. (AU)

Kinetics of viral RNA, immunoglobulin-M & G antibodies in Kyasanur forest disease

Background & objectives: Kyasanur forest disease (KFD) is an infectious disease discovered in Karnataka State of India in 1957; since then, the State has been known to be enzootic for KFD. In the last few years, its presence was observed in the adjoining five States of the Western Ghats of India. The present study was conducted to understand the kinetics of viral RNA, immunoglobulin M (IgM) and IgG antibody in KFD-infected humans for developing a diagnostic algorithm for KFD. Methods: A prospective follow up study was performed among KFD patients in Sindhudurg district of Maharashtra State, India. A total of 1046 suspected patients were tested, and 72 KFD patients were enrolled and followed for 17 months (January 2016 to May 2017). Serum samples of KFD patients were screened for viral RNA, and IgM and IgG antibodies. Results: KFD viral positivity was observed from 1st to 18th post-onset day (POD). Positivity of anti-KFD virus (KFDV) IgM antibodies was detected from 4th till 122nd POD and anti-KFDV IgG antibodies detected from 5th till 474th POD. A prediction probability was determined from statistical analysis using the generalized additive model in R-software to support the laboratory findings regarding viral kinetics. Interpretation & conclusions: This study demonstrated the presence of KFD viral RNA till 18th POD, IgM antibodies till 122nd POD and IgG till the last sample collected. Based on our study an algorithm was recommended for accurate laboratory diagnosis of KFDV infection. A sample collected between 1 and 3 POD can be tested using KFDV real-time reverse transcriptase polymerase chain reaction (RT-PCR); between 4 and 24 POD, the combination of real-time RT-PCR and anti-KFDV IgM enzyme-linked immunosorbent assay (ELISA) tests can be used; between POD 25 and 132, anti-KFDV IgM and IgG ELISA are recommended.

RIG-I: a multifunctional protein beyond a pattern recognition receptor

It was widely known that retinoic acid inducible gene I (RIG-I) functions as a cytosolic pattern recognition receptor that initiates innate antiviral immunity by detecting exogenous viral RNAs. However, recent studies showed that RIG-I participates in other various cellular activities by sensing endogenous RNAs under different circumstances. For example, RIG-I facilitates the therapy resistance and expansion of breast cancer cells and promotes T cell-independent B cell activation through interferon signaling activation by recognizing non-coding RNAs and endogenous retroviruses in certain situations. While in hepatocellular carcinoma and acute myeloid leukemia, RIG-I acts as a tumor suppressor through either augmenting STAT1 activation by competitively binding STAT1 against its negative regulator SHP1 or inhibiting AKT-mTOR signaling pathway by directly interacting with Src respectively. These new findings suggest that RIG-I plays more diverse roles in various cellular life activities, such as cell proliferation and differentiation, than previously known. Taken together, the function of RIG-I exceeds far beyond that of a pattern recognition receptor.

Distinctive Drug-resistant Mutation Profiles and Interpretations of HIV-1 Proviral DNA Revealed by Deep Sequencing in Reverse Transcriptase / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate distinctive features in drug-resistant mutations (DRMs) and interpretations for reverse transcriptase inhibitors (RTIs) between proviral DNA and paired viral RNA in HIV-1-infected patients.</p><p><b>METHODS</b>Forty-three HIV-1-infected individuals receiving first-line antiretroviral therapy were recruited to participate in a multicenter AIDS Cohort Study in Anhui and Henan Provinces in China in 2004. Drug resistance genotyping was performed by bulk sequencing and deep sequencing on the plasma and whole blood of 77 samples, respectively. Drug-resistance interpretation was compared between viral RNA and paired proviral DNA.</p><p><b>RESULTS</b>Compared with bulk sequencing, deep sequencing could detect more DRMs and samples with DRMs in both viral RNA and proviral DNA. The mutations M184I and M230I were more prevalent in proviral DNA than in viral RNA (Fisher's exact test, P<0.05). Considering 'majority resistant variants', 15 samples (19.48%) showed differences in drug resistance interpretation between viral RNA and proviral DNA, and 5 of these samples with different DRMs between proviral DNA and paired viral RNA showed a higher level of drug resistance to the first-line drugs. Considering 'minority resistant variants', 22 samples (28.57%) were associated with a higher level of drug resistance to the tested RTIs for proviral DNA when compared with paired viral RNA.</p><p><b>CONCLUSION</b>Compared with viral RNA, the distinctive information of DRMs and drug resistance interpretations for proviral DNA could be obtained by deep sequencing, which could provide more detailed and precise information for drug resistance monitoring and the rational design of optimal antiretroviral therapy regimens.</p>

Hepatitis C aguda: Acute hepatitis C

La hepatitis C aguda es una enfermedad generalmente subclínica, de ahí que no se incluya en el diagnóstico diferencial de los pacientes con un cuadro agudo. Además diagnosticarla presenta dificultades ya que los anticuerpos contra el virus tardan en aparecer, pudiendo ser negativos cuando el paciente manifiesta los síntomas; en este punto la enfermedad podría diagnosticarse con el RNA viral, pero éste no es fácil que sea solicitado inicialmente. Se presenta un paciente que ingresó por una hepatitis aguda en el que se descartaron causas virales como hepatitis A-B, Ebstein Barr, Citomegalovirus (CMV) hepatitis autoinmune, hepatotoxicidad y enfermedad hipoxicoisquémica, que explicaran la sintomatología y los hallazgos bioquímicos del paciente, en quien se demostró seroconversión contra el virus de la hepatitis C asociado a una carga viral elevada. Todo lo anterior es consistente con un diagnóstico de hepatitis C aguda. Se describe el manejo del paciente y las características de la enfermedad.

Acute hepatitis C is usually a sub-clinical disease, thus it is not included in the differential diagnosis of patients with acute disease. Making the diagnosis is also difficult because the virus antibodies appear at later stages and many even be negative even if the patient has symptoms; at this point the diagnosis of the disease could be made with the viral RNA, but it is not easy to ask for it initially. A patient is admitted because of acute hepatitis where viral causes such as hepatitis A-B, Epstein Barr, Cytomegalovirus (CMV), auto-immune hepatitis, hepatoxitiy and hypoxic-isquemic disease, that would explain the symptoms and bio-chemical findings were discarded. The patient’s seroconversion against Hepatitis C virus associated to a high viral load was demonstrated. All this is consistent with an acute Hepatitis C diagnosis. Patient’s management and disease characteristics are described. (Acta Med Colomb 2008; 33: 28-32).

Expression of Plus- and Minus-strand Viral RNA in Coxsackievirus B3-Infected A/J Mice

In order to investigate the implication of viral replication in acute, subacute, and chronic infections of coxsackievirus B3 (CVB3), we examined the histopathological changes and plus- and minus-strand viral RNA dynamics in heart, pancreas, brain, and liver of CVB3-infected A/J mice. Mice were inoculated intraperitoneally with CVB3 and sacrificed on 1, 2, 3, 4, 7, 10, 14, 21, 30, 60, and 90 days post infection (p.i.). Plus- and minus-strand viral RNAs in the organs were quantitated and the organs were additionally evaluated histopathologically for inflammation. No inflammatory infiltrates were observed in the liver, brain, and heart. In contrast, massive lymphocyte infiltration and fat replacement were shown in the pancreas with loss of acinar cells. Both plus- and minus-strand viral RNA levels were detected by 21 days p.i. in heart, 90 days p.i. in pancreas, 4 days p.i. in liver, and 10 days p.i. in brain. The plus-strand RNA was found at least fifty fold higher than the minus-strand RNA by 4 days p.i. in heart and pancreas and by 3 days p.i. in liver. The plus- to minus-strand RNA ratio in brain was found less than 1:20. Our data indicate that viral replication was actively occurred in heart, pancreas, and liver during acute CVB3 infection, whereas viral replication was limited in brain. Furthermore, chronic persistent viral RNA was observed in pancreas. In conclusion, CVB3 at low dose of virus induces severe pancreatitis but marginal or no inflammatory changes in the heart, liver, and brain.

Characterisation of rinderpest virus RNA and the action of actinomycin D on its replication.

RNA extracted from purified rinderpest virus was characterised by sucrose gradient sedimentation and polyacrylamide gel electrophoresis. The predominant virion RNA species had a sedimentation constant of 46S and its estimated molecular weight was 4·8 × 106 daltons. Consistently high amounts of UMP and AMP were detected. The melting-temperature profile of the virion RNA suggested absence of secondary structure. The effect of actionomycin D on the replication of rinderpest virus in Vero cells was studied by following the viral RNA synthesis using labelled uridine as well as by infectivity titration. The viral RNA synthesis was not affected until 12 h following infection and was inhibited thereafter between 18 and 48 h to an extent of 25% at 5 and 10 μg levels of the drug. A 100 to 1000-fold reduction in the infectivity titres was observed in the presence of the drug. These results suggest that actinomycin D inhibits rinderpest viral RNA replication. Sedimentation analysis of viral RNA extracted from drug-treated cultures showed inhibition of the genome RNA of rinderpest virus.