COVID-19: An Update on Pathogenesis and Treatment

: In 2019, a new virus –SARS-COV2 emerged in china which infected many people affecting mainly the respiratory system. SARS-COV2 gets transmitted by inhalation of droplets from infected persons. Symptoms start to appear after the incubation period of the virus which ranges from 2 to 14 days. In most people, symptoms are usually mild such as fever, sore throat, cough, chest tightness and fatigue. In other people, the disease might progress into severe pneumonia leading to several fatal consequences. Treatment is usually supportive and the role of antiviral is not established yet. Home isolation for mild cases is important for the prevention of the transmission of infection. Although the rate of transmission of this virus is faster than other viruses from the family such as MERS-CoV, it has a lower fatality rate. The main difference in the genome structure of this family which make it distinguishable from other viruses is its use of (+) ssRNA as its genetic material which is comprised of 5’ cap located at one end and 3' polyadenylation tract at the other end. During infection of an exposed host cell, viral-encoded protease cleaves the polyprotein that results from translation of 5’ open reading frame (ORF) of the genome, culminating in releasing of multiple nonstructural proteins such as helicase (Hel), adenosine triphosphate (ATPase) and RNA-dependent RNA polymerase (Rep). These proteins are responsible for the replication process in addition to the syntheses of the sub genomic mRNA used as transcription templet strand. In this review article we discussed the transmission pathways, genetic sequence and current treatment approach of COVID-19.

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Coronavirus: history, genome structure and pathogenesis

Coronaviruses ◽

10.2174/2666796701999200918160354 ◽

2020 ◽

Vol 01 ◽

Author(s):

Poonam B ◽

Prabhjot Kaur Gill

Keyword(s):

Genome Structure ◽

Public Health Research ◽

Replication Process ◽

Virus Family ◽

Enveloped Virus ◽

Target Organs ◽

Transcription Process ◽

Recent Emergence ◽

The Family ◽

Discontinuous Transcription

Background: The positive sense and inordinate large RNA genome are enclosed by helical nuceocapsids along with an outermost layer belongs to the family Coronaviridae. The phylogenetic tree of this family has been quartered into Class1 as alpha, Class 2 as beta, Class 3 as gamma and Class 4 as delta CoV. The mammalian respiratory and gastrointestinal tracts are the main target organs of this enveloped virus with misperceived mechanisms. The relevance of this virus family has considerably increased by the dint of recent emergence of the Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS), which are caused by viruses belonging to the beta-CoV group. Aim: Aforesaid illustrations of emergence of coronavirus diseases over the past two decades, SARS (2002 and 2003) and MERS (2012 to present) - the ongoing COVID-19 outbreak has pressurized the WHO to take innovative measures for public health, research and medical communities. The aim of the present review is to have proficiency in coronavirus replication and transcription process which is still in its infancy. Conclusion: An outcome of epidemics, it is being recognized as one of the most advancing viruses by the virtue of high genomic nucleotide substitution rates and recombination. The hallmark of coronavirus replication is discontinuous transcription resulting in the production of multiple subgenomic mRNAs having sequences complementary to both ends of the genome. Therefore, complete genome sequence of coronavirus will be used as frame of reference for knowing this classical phenomenon of RNA replication process. Finally, research on the pathogenesis of coronaviruses and the host immunopathological response will aid in designing vaccines and minimizing mortality rate.

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Sperm Cryopreservation in American Flamingo (Phoenicopterus Ruber): Influence of Cryoprotectants and Seminal Plasma Removal

Animals ◽

10.3390/ani11010203 ◽

2021 ◽

Vol 11 (1) ◽

pp. 203

Author(s):

María Gemma Millán de la Blanca ◽

Eva Martínez-Nevado ◽

Cristina Castaño ◽

Juncal García ◽

Berenice Bernal ◽

...

Keyword(s):

Seminal Plasma ◽

Genetic Material ◽

First Year ◽

Sperm Cryopreservation ◽

Straight Line ◽

The Family ◽

Second Year ◽

American Flamingo ◽

Phoenicopterus Ruber

The American flamingo is a useful model for the development of successful semen cryopreservation procedures to be applied to threatened related species from the family Phoenicopteridae, and to permit genetic material banking. Current study sought to develop effective sperm cryopreservation protocols through examining the influences of two permeating cryoprotectants and the seminal plasma removal. During two consecutive years (April), semen samples were collected and frozen from American flamingos. In the first year, the effect of two permeating cryoprotectants, DMA (dimethylacetamide) (6%) or Me2SO (dimethylsulphoxide) (8%), on frozen–thawed sperm variables were compared in 21 males. No differences were seen between DMA and Me2SO for sperm motility, sperm viability, and DNA fragmentation after thawing. In the second year, the role of seminal plasma on sperm cryoresistance was investigated in 31 flamingos. Sperm samples were cryopreserved with and without seminal plasma, using Me2SO (8%) as a cryoprotectant. The results showed that samples with seminal plasma had higher values than samples without seminal plasma for the following sperm variables: Straight line velocity (22.40 µm/s vs. 16.64 µm/s), wobble (75.83% vs. 69.40%), (p < 0.05), linearity (62.73% vs. 52.01%) and straightness (82.38% vs. 73.79%) (p < 0.01); but acrosome integrity was lower (55.56% vs. 66.88%) (p < 0.05). The cryoresistance ratio (CR) was greater in samples frozen with seminal plasma than without seminal plasma for CR-progressive motility (138.72 vs. 54.59), CR-curvilinear velocity (105.98 vs. 89.32), CR-straight line velocity (152.77 vs. 112.58), CR-average path velocity (122.48 vs. 98.12), CR-wobble (111.75 vs. 102.04) (p < 0.05), CR-linearity (139.41 vs. 113.18), and CR-straightness (124.02 vs. 109.97) (p < 0.01). This research demonstrated that there were not differences between Me2SO and DMA to successful freezing sperm of flamingos; seminal plasma removal did not provide a benefit for sperm cryopreservation.

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Complete genome sequence of a novel mitovirus isolated from Paris polyphylla var. yunnanensis

10.21203/rs.3.rs-890311/v1 ◽

2021 ◽

Author(s):

Zeli Chen ◽

Lu Chen ◽

Rex Frimpong Anane ◽

Zhe Wang ◽

Like Gao ◽

...

Keyword(s):

Genome Sequence ◽

Complete Genome Sequence ◽

Complete Genome ◽

Rna Virus ◽

Genome Structure ◽

Complementary Sequence ◽

Reading Frame ◽

A Genome ◽

Paris Polyphylla ◽

The Family

Abstract Paris mitovirus 1 (ParMV1) is a positive-sense RNA virus isolated from diseased Paris polyphylla var. yunnanensis plants in Wenshan, Yunnan. The complete genome sequence of ParMV1 consists of 2,751 nucleotides with a genome structure typical of the mitoviruses. ParMV1 genome has a single open reading frame (ORF: 358-2,637 nt) that encodes RNA-dependent RNA polymerase (RdRp) with a molecular mass of 86.42 kDa. ParMV1 contains six conserved motifs (Ι-VΙ) that are unique to mitoviruses. In addition, the 5′and 3′ terminals of the genome have a stable secondary structure, and the reverse complementary sequence forms a panhandle structure. Comparative genome analysis revealed that ParMV1 shares 23.1–40.6% amino acid (aa) and 32.3–45.7% nucleotide (nt) sequence identities with the RdRp of other mitoviruses. The phylogenetic tree inferred from RdRp aa sequence showed that ParMV1 clusters with mitoviruses, and hence should be considered as a new member of the genus Mitovirus in the family Motiviridae. This is the first report of a novel mitovirus infecting Paris polyphylla var. yunnanensis.

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Identification and Characterization of a Novel Emaravirus From Grapevine Showing Chlorotic Mottling Symptoms

Frontiers in Microbiology ◽

10.3389/fmicb.2021.694601 ◽

2021 ◽

Vol 12 ◽

Author(s):

Xudong Fan ◽

Chen Li ◽

Zunping Zhang ◽

Fang Ren ◽

Guojun Hu ◽

...

Keyword(s):

Phylogenetic Trees ◽

High Throughput Sequencing ◽

Rna Virus ◽

Reading Frame ◽

A Genome ◽

The Family ◽

Pcr Products ◽

Chlorotic Mottling

A novel negative-sense, single-stranded (ss) RNA virus was identified in a “Shennong Jinhuanghou” (SJ) grapevine showing severe chlorotic mottling symptoms by integrating high-throughput sequencing (HTS) and conventional Sanger sequencing of reverse transcription polymerase chain reaction (RT-PCR) products. The virus was provisionally named as “grapevine emaravirus A” (GEVA). GEVA had a genome comprising five genomic RNA segments, each containing a single open reading frame on the viral complementary strand and two untranslated regions with complementary 13- nt stretches at the 5′ and 3′ terminal ends. RNA1 (7,090 nt), RNA2 (2,097 nt), RNA3 (1,615 nt), and RNA4 (1,640 nt) encoded putative proteins P1–P4 that, based on their conserved motifs, were identified as the RNA-dependent RNA polymerase, glycoprotein, nucleocapsid protein, and movement protein, respectively. However, the functional role of protein P5 encoded by RNA5 (1,308 nt) could not be determined. Phylogenetic trees constructed based on amino acids of P1 to P4, allocated GEVA in clade I, together with other species-related emaraviruses. These data support the proposal that GEVA is a representative member of a novel species in the genus Emaravirus of the family Fimoviridae. Moreover, when GEVA was graft-transmitted to SJ and “Beta” grapevines, all grafted plants showed the same symptoms, similar to those observed in the source of the inoculum. This is the first report to our knowledge of an emaravirus infecting grapevine and its possible association with chlorotic mottling symptoms.

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CORONAVIRUS (GENOME STRUCTURE, REPLICATION)

Crimea Journal of Experimental and Clinical Medicine ◽

10.37279/2224-6444-2020-10-4-78-95 ◽

2021 ◽

Vol 10 (4) ◽

pp. 78-95

Author(s):

A. B. Khaitovich

Keyword(s):

Genome Structure ◽

Structural Genes ◽

Replication Process ◽

Literary Sources ◽

Viral Particles ◽

Different Types ◽

Genes Encoding ◽

Medical Importance ◽

Genetic Structures

The overview presented in the article is a continuation of the publication on coronaviruses. The paper examines modern data on the structure of the genome and the replication process in various types of coronaviruses that cause diseases in humans and are of medical importance. The structure of the genomes of coronaviruses and the functions of genes that encode the structure of viral particles are presented; describes the function of structural genes and auxiliary genes; the role of genes encoding non-structural proteins in the structure of the viral particle and replication of coronaviruses is shown. The analysis of published studies made it possible to comparatively characterize the genomes of highly dangerous coronaviruses: SARS-CoV, MERS-CoV, SARS-CoV-2, describe their differences in structure and in the process of replication. The review analyzes the structure of the genome and the replication process of coronaviruses at the molecular level, taking into account the characteristics of different types of coronaviruses. To analyze the genetic structures and replication of coronaviruses, modern literary sources, articles in the world’s leading medical and biological journals were used.

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Identification of a Plasmid-Encoded Gene fromHaemophilus ducreyi Which Confers NAD Independence

Journal of Bacteriology ◽

10.1128/jb.183.4.1168-1174.2001 ◽

2001 ◽

Vol 183 (4) ◽

pp. 1168-1174 ◽

Cited By ~ 108

Author(s):

Paul R. Martin ◽

Robin J. Shea ◽

Martha H. Mulks

Keyword(s):

Pasteurella Multocida ◽

Deinococcus Radiodurans ◽

Single Gene ◽

Bacterial Species ◽

Mycoplasma Genitalium ◽

Reading Frame ◽

Defined Media ◽

The Family ◽

Cloned Gene

ABSTRACT Members of the family Pasteurellaceae are classified in part by whether or not they require an NAD supplement for growth on laboratory media. In this study, we demonstrate that this phenotype can be determined by a single gene, nadV, whose presence allows NAD-independent growth of Haemophilus influenzae andActinobacillus pleuropneumoniae. This gene was cloned from a 5.2-kb plasmid which was previously shown to be responsible for NAD independence in Haemophilus ducreyi. When transformed intoA. pleuropneumoniae, this cloned gene allowed NAD-independent growth on complex media and allowed the utilization of nicotinamide in place of NAD on defined media. Sequence analysis revealed an open reading frame of 1,482 bp that is predicted to encode a protein with a molecular mass of 55,619 Da. Compared with the sequence databases, NadV was found to have significant sequence homology to the human pre-B-cell colony-enhancing factor PBEF and to predicted proteins of unknown function identified in the bacterial species Mycoplasma genitalium, Mycoplasma pneumoniae, Shewanella putrefaciens, Synechocystis sp., Deinococcus radiodurans, Pasteurella multocida, and Actinobacillus actinomycetemcomitans. P. multocida and A. actinomycetemcomitans are among the NAD-independent members of the Pasteurellaceae. Homologues of NadV were not found in the sequenced genome of H. influenzae, an NAD-dependent member of thePasteurellaceae, or in species known to utilize a different pathway for synthesis of NAD, such as Escherichia coli. Sequence alignment of these nine homologues revealed regions and residues of complete conservation that may be directly involved in the enzymatic activity. Identification of a function for this gene in thePasteurellaceae should help to elucidate the role of its homologues in other species.

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