The emergence of 2019-nCoV
The appearance of a new viral outbreak from Wuhan City, China, in Hubei Province, named as 2019-nCoV has now turned into a global concern. Owing to the rising number of infected cases and widespread detection of 2019-nCoV, the International Health Regulations Emergency Committee of the World Health Organization (WHO) declared the 2019-nCoV outbreak a “public health emergency of international concern (PHEIC) on 30 January 2020. Previous outbreaks of coronavirus such as severe acute respiratory syndrome (SARS) (SARS-CoV) (Hui and Zumla, 2019) or Middle Eastern respiratory syndrome (MERS) (MERS-CoV) (Al-Tawfiq et al., 2013) both left 774 and 850 deaths respectively, reflect the severity of the threat and urgency to resolve this outbreak as soon as possible.

The transmissibility of 2019-nCoV, or at least its geographical distribution, seems to be higher and broader than expected due to the vast transport network used in China. It is anticipated that more cases will be spread to other countries and that further transmission may occur, regardless of the initial source of 2019-nCoV still remains unknown. Several studies have reported that although uncounted of the first confirmed cases of 2019-nCoV in China worked or visited the Huanan market. Based on the preliminary findings, these factors have been identified. The Huanan seafood market located in Wuhan City is the first and most important reason (World Health Organization (WHO), 2020). On the other hand, the market has remained closed since January 1, 2020. As of March 5, 2020, a total of 80581 confirmed 2019-nCoV cases along with 522 suspected cases had been reported in China. Recent stats on the emergence and widespread distribution of novel-Coronavirus (2019-nCoV) in different provinces of CHINA are summarized in Table 1. Whereas, current stats on the appearance and worldwide 2019-nCoV cases in different countries are shown in Figure 1. In order to overcome this health contingency, it is necessary to take the corresponding measures. For instance, the timely detention of the trade-in suspected animals of Wuhan City. Likewise, trade routes must be monitored from the site of the outbreak as well as identify the animals responsible for the infection and the development of additional control and prevention strategies.

Table (1):
Recent stats on the emergence and widespread distribution of novel-Coronavirus (2019-nCoV) in different provinces of CHINA. Data Source: IFENG News. Available online at the link:
https://jobtube.cn/wv/?from=singlemessage&isappinstalled=0.

Replication cycle of 2019-nCoV
The recently reemerged 2019-nCoV is an enveloped positive-sense RNA virus. It is characterized by club-like spikes projecting from its surface (Phan, 2020). Coronavirus is a complex pathogen with a high capability to infect multiple host species (Fung et al., 2019). Thus, cause a variety of diseases with numerous symptoms. A mechanistic representation of endocytosis and exocytosis-based Coronavirus entry and exit to and from the host, respectively, is shown in Figure 2. The main steps involved in the replication cycle are (1) binding and 2019-nCoV entry to the host via membrane fusion or endocytosis mechanism, (2) upon entrance to the host, release of viral genome, (3) translation of viral polymerase protein, (4) RNA replication, (5) sub-genomic transcription, (6) translation of viral structural protein, (7) viral structural proteins combine with nucleocapsid, (8) formation of mature virion, and (9) release of mature virion via exocytosis mechanism. At the end of the cycle, the newly released mature virion can further infect a new target, and it continues consecutively.

Concluding remarks
Owing to this new emergence, we know fairly little about 2019-nCoV. However, as evident from the current WHO announcement about 2019-nCoV as a global health emergency, 2019-nCoV is a highly pathogenic human pathogen. To completely overcome this life-threatening 2019-nCoV pathogen, further in-depth studies are needed to gain insight and complete understanding about its fast mode spread, replication, and pathogenesis.