REVIEW ON STRUCTURE, PATHOGENECITY, TRANSMISSIBILITY AND EPIDEMIOLOGY OF HUMAN PATHOGENIC CORONAVIRUSES

Coronaviruses cause animal and human respiratory and bowel infections. They have not been deemed highly pathogenic to humans until the outbreak of severe acute respiratory syndrome (SARS) in 2002 and 2003 in Guangdong province, China. Coronaviruses (CoVs) are large, enveloped, positive-sense, single-stranded RNA viruses that can infect both animals and humans. Coronaviruses didn't just appear recently. They are large family of viruses that have been around for a long time. Formerly, coronaviruses (CoVs) were seen as relatively harmless respiratory pathogens to humans. However, two outbreaks of severe respiratory tract infection, caused by the severe acute respiratory syndrome coronavirus (SARS-CoV) and the Middle East respiratory syndrome coronavirus (MERS-CoV) caused high pathogenicity and mortality rates among human populations as a result of zoonotic CoVs crossing the species barrier. Now the recent detection of the 2019 novel coronavirus (COVID-19), added a new member in corona virus family.The novel coronavirus (COVID 19) is one of the member of coronavirus family which infect human. Scientists have divided coronaviruses into four sub- groupings, called alpha, beta, gamma and delta. Seven of these viruses can infect people. The four common coronaviruses are-229E(alpha), NL63(alpha), OC43(beta), HKU1(beta). The three less-common coronaviruses are- MERS-CoV(beta), SARS-CoV(beta), SARS-CoV-2. Our main target is to describe the the structure, Pathogenecity, Transmissibility and Epidemiology of above mentioned subgroups of corona viruses in our review

A semi-nested RT-PCR assay targeted to hemagglutinin-esterase gene of Bovine Coronavirus / Reação de hemi-nested RT-PCR dirigida ao gene da hemaglutinina-esterase do Coronavírus Bovino

Bovine coronavirus (BCoV) is a non-segmented positive-sense single-stranded RNA virus whose envelope is constituted by a lipid bilayer with four structural proteins (HE, S, E and M) giving its characteristic crown-like virions appearance. Hemagglutinin-esterase (HE), is a polymorphic protein with a function of secondary receptor binder, and studies on the diversity of HE gene allow insights on BCoV evolution and host-parasite interactions. A semi-nested RT-PCR was developed for the amplification of a 441bp-long product of the HE gene of BCoV (nt 543 to 562). Optimal annealing temperatures were tested in a gradient thermocycler for the semi-nested assay and employed in the final protocol. The analytical sensitivity was determined by 10-fold serial dilutions of the BCoV Kakegawa strain (HA titer: 256) in a BCoV-free fecal suspension, with positive results up to 10-6 dilution, a high analytical sensitivity without PCR inhibition. The final semi-nested RT-PCR protocol was applied to 21 fecal samples of cows previously positive to BCoV and DNA sequencing of the 441bp amplicons of 14 of these resulted in highly-scored BCoV HE gene sequences after BLAST/n analysis. This semi-nested RT-PCR is a powerful tool for surveys of phylogenetic diversity in field strains of BCoV and for comparative studies among different genes of Coronavirus.

O coronavírus bovino (BCoV) é um vírus RNA simples fita, de sentido positivo, não segmentado com envelope constituído de uma camada dupla de lipídios com quatro proteínas (HE, S, E e M) que resultam no aspecto de coroa dos vírions. Como a HE (hemaglutinina-esterase) é uma proteína polimórfica com uma função de receptor aglutinante secundária, estudos sobre a diversidade do gene HE podem possibilitar maiores informações sobre a evolução e interação hospedeiro-parasita do BCoV. Uma reação de hemi-nested RT-PCR foi desenvolvida para a amplificação de um produto de 441pb do gene HE do BCoV (nt 543 ao 562). Temperaturas ótimas de hibridização foram testadas em um termociclador com gradiente para a reação de hemi-nested e utilizada no protocolo final. A sensibilidade analítica foi determinada por meio da diluição serial na base 10 do BCoV amostra Kakegawa (título HA: 256) em uma suspensão fecal negativa para BCoV, resultando positiva até a diluição de 10-6, mostrando uma alta sensibilidade analítica sem inibição na PCR. O protocolo final da hemi-nested RT-PCR foi aplicado a 21 amostras fecais de vacas previamente positivas para BCoV e o sequenciamento de DNA do produto de 441pb de 14 amostras resultaram em sequências com elevado escore do gene HE do BCoV após a análise no BLAST/n. Essa hemi-nested RT-PCR é uma ferramenta poderosa para estudos de diversidade filogenética de linhagens de campo de BCoV e para estudos comparativos entre os diferentes genes dos Coronavírus.