In Jan 2020, the outbreak of the 2019 novel coronavirus (SARS-CoV-2) in Wuhan, Hubei Province of China spread increasingly to other countries worldwide which WHO declared it as a public health emergency of international concern. Iran was included in the affected countries. Throat swab specimens were collected and tested by using real-time reverse transcription PCR (RT-PCR) kit targeting the E region for screening and RNA dependent RNA polymerase for confirmation. Conventional RT-PCR was conducted for the N region and the PCR products were sequenced by Sanger sequencing. The first seven cases of SARS-CoV-2 infections were identified in Qom, Iran. This report describes the clinical and epidemiological features of the first cases of SARS-CoV-2 confirmed in Iran. Future research should focus on finding the routes of transmission for this virus, including the possibility of transmission from foreign tourists to identify the possible origin of SARS-CoV-2 outbreak in Iran.

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Coronaviruses recognize a variety of host receptors to infect many humans and animals. Newly emerged severe acute respiratory syndrome coronavirus2 (SARS-CoV-2) recognizes angiotensin-converting enzyme 2 (ACE2) to gain entry into different cells. Interestingly, besides SARS-CoV2, four other human coronaviruses (HCoVs) use three different ectopeptidases (ACE2, dipeptidyl peptidase 4, and aminopeptidase N) as receptors independent of their common peptidase activity. This issue has led to the important question "why do several HCoVs rely on peptidases as their receptors?." In this paper, we discussed to answer this question. Mostly, it seems that the use of peptidases by HCoVs may be more related to their widespread presence on target cells and also viruses prefer to take advantage of molecules with relatively low affinity for their natural ligands through evolving a stronger binding affinity to the surface receptors for entry and endocytosis. Meanwhile evolutionary conservation of these receptors may allow HCoVs to switch between different host species. Finally, the choice of peptidases by HCoVs may reflect the "trial and error" nature of evolution. In conclusion, substantial efforts are needed to get a strong picture of this fascinating question and poorly explored area. Detailed understanding of the entry mechanisms offers opportunities for the development of refined strategies to stop viruses.

Respiratory tract infection is a frequent cause of pediatric morbidity and mortality and a common reason for admission in acute care hospitals and outpatients visits. Appropriate diagnostic testing is important for specific diagnosis at an early stage of the illness because of the similarity in clinical presentation of patients with different viral infections caused by several respiratory pathogens.

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