1. Introduction
Coronavirus Disease- 2019 (COVID-19) originated from a sea food market
at Wuhan city (the capital of Hubei province at the south east of China)
and spread rapidly in more than 200 countries. On 2 Jul 2020, the total
confirmed cases reached more than 10.5 million and 512000 deaths. The
symptoms of COVID 19 include cough, fever, headache, fatigue, sore
throat and malaise. The disease can be complicated to pneumonia and
severe acute respiratory syndrome [1-3]. The COVID 19 is transmitted
through direct or indirect contact with respiratory droplets and
biological samples such as urine, saliva and stool [4]. However,
some studies proved the presence of the virus in air samples and one
study stated that the virus from air samples is viable for up to three
hours [5-8].
Coronavirus 19 is named by the WHO and the International Committee on
Taxonomy of Viruses (ICTV) as SARS-CoV-2 and is grouped in the same
class of SARS-CoV [9]. The two viruses belong to the family:
Coronaviridae; subfamily: Orthocoronavirinae; genus: betacoronavirus;
subgenus: sarbecovirus; species: Severe Acute Respiratory Syndrome-
related coronavirus. The bat coronavirus (BatCoV RaTG13) was isolated
from the bat genus Rhinolophus affinis. As the SARS-CoV-2 and
SARS-CoV, The bat coronavirus (BatCoV RaTG13) belongs to the beta
coronaviruse and it has 96% genome sequence identity compared to the
genome of SARS-CoV-2 [10].
The SARS-CoV-2, SARS-CoV, and the bat coronavirus (BatCoV RaTG13) have
the same virion structure. They have an RNA with nucleocapsid protein
and an envelope. The viral envelope contains a bi-lipid membrane and
three proteins: the spike protein, envelope protein and membrane protein
[11].
The three viruses contain two major genes: The orf 1ab and 1a (two
third) and the structural and accessory proteins gene (one third). The
Orf 1ab and 1a genes are translated and hydrolyzed to produced 16
nonstructural proteins (nsp1- nsp16) while the translation of the second
gene produces the structural proteins spike (S), envelope (E), membrane
(M), and nucleocapsid (N); and the accessory proteins orf3a, orf3b,
orf6, orf7a, orf7b, orf8a, orf8b, orf9b and orf10. The number and type
of the accessory proteins differs according to the virus [10,
12-16].
Regarding the NS3, NS6, NS7a, NS7b and NS8 of the BatCoV RaTG13, some
published articles named them as nonstructural proteins [16-17] and
others named them as accessory proteins [18,19]. Because these
proteins are located in the gene of the structural and accessory
proteins, they are considered as accessory proteins and compared to the
accessory proteins of SARS-CoV-2.
This article investigated the protein sequence identity and similarity
percentages of SARS-CoV-2 compared to the proteins of SARS-CoV and the
BatCoV RaTG13.