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N Protein

The N protein of coronavirus is multipurpose. Atnong several functions, it plays a role in co1nplex fonnation with the viral geno1ne, facilitates M protein interaction needed during virion assembly, and enhances the transcription efficiency of the virus (55, 56). It contains three highly conserved and distinct don1ains, na1nely, an NTD, an RNA-binding do1nain or a linker region (LKR), and a CTD (57). The NTD binds with the 3' end of the viral geno1ne, perhaps via electrostatic interactions, and is highly diverged both in length and sequence (58). The charged LKR is serine and arginine rich and is also known as the SR (serine and arginine) do1nain (59). The LKR is capable of direct interaction with in vitro RNA interaction and is responsible for cell signaling (60, 61). It also 1nodulates the antiviral response of the host by working as an antagonist for interferon (IFN) and RNA interference (62). Co1npared to that of SARS-CoV, the N protein of SARS-CoV-2 possess five a1nino acid mutations, where two are in the intrinsically dispersed region (IDR; positions 25 and 26), one each in the NTD (position 103), LKR (position 217), and CTD (position 334) (16).

nsps and Accessory Proteins

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adapl1vc c,,olul1on, close n10111lonng o1 the viral 111utations that occur during subsequent hu1nan-to­ hu1nan trans1nission is warranted.

M Protein

The M protein is the 1nost abundant viral protein present in the virion particle, giving a definite shape to the viral envelope (48). It binds to the nucleocapsid and acts as a central organizer of coronavirus assembly (49). Coronavirus M proteins are highly diverse in ainino acid contents but n1aintain overall structural sin1ilarity within different genera (50). The M protein has three transmembrane domains, flanked by a short an1ino terminus outside the virion and a long carboxy tenninus inside the virion (50). Overall, the viral scaffold is 1naintained by M-M interaction. Of note, the M protein of SARS-CoV-2 does not have an a1nino acid substitution co1npared to that of SARS-CoV (16).

E Protein

The coronavirus E protein is the most enigmatic and s1nallest of the major structural proteins (51). It plays a n1ultifunctional role in the pathogenesis, asse1nbly, and release of the virus (52). It is a small integral 1ne1nbrane polypeptide that acts as a viroporin (ion channel) (53). The inactivation or

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progress fron1 the initial focal unilateral to difiuse bilateral ground-glass opacities and will further progress to or coexist with lung consolidation changes within 1 to 3 weeks (159). The role played by radiologists in the current scenario is very important. Radiologists can help in the early diagnosis of lung abnonnalities associated with COVID-19 pneumonia. They can also help in the evaluation of disease severity, identifying its progression to acute respiratory distress syndrome and the presence of secondary bacterial infections
(160). Even though chest CT is considered an essential diagnostic tool for COVID-19, the extensive use of CT for screening purposes in the suspected individuals might be associated with a disproportionate risk-benefit ratio due to increased radiation exposure as well as increased risk of cross­ infection. Hence, the use of CT for early diagnosis of SARS-CoV-2 infection in high-risk groups should be done with great caution (292).
More recently, other advanced diagnostics have been designed and developed for the detection of SARS-CoV-2 (345, 347, 350-352). A reverse
transcriptional loop-1nediated isothennal mnplification (RT-LAMP), na1nely, iLACO, has been developed for rapid and colorimetric detection of this

links associated with SARS-CoV-2, the One Health approach 111ay play a vital role in the prevention and control 1neasures being followed to restrain this pande1nic virus (317-319). The substantial i1nportation of COVID-19 presympto1natic cases from Wuhan has resulted in independent, self­ sustaining outbreaks across 1najor cities both within the country and across the globe. The 1najority of Chinese cities are now facing localized outbreaks of COVID-19 (231). Hence, deploying efficient public health interventions might help to cut the spread of this virus globally.
The occurrence of COVID-19 infection on several cruise ships gave us a preli1ninary idea regarding the trans1nission pattern of the disease. Cruise ships act as a closed environment and provide an ideal setting for the occurrence of respiratory disease outbreaks. Such a situation poses a significant threat to travelers, since people from different countries are on board, which favors the introduction of the pathogen (320). Although nearly 30 cruise ships fro1n different countries have been found harboring COVID-19 infection, the major cruise ships that were involved in the COVID-19 outbreaks are the Diamond Princess, Grand Princess, Celebrity Apex, and Ruby Princess. The



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viruses in nasal washes, saliva, urine and faeces for up to 8 days after infection, and a few naive ferrets with only indirect contact were positive for viral RNA, suggest­ ing airborne transmission⁷⁸• In addition, transmission of the virus through the ocular surface and prolonged presence of SARS-CoV-2 viral RNA in faecal samples were also documented ^{101 102}• Coronaviruses can persist on inanin1ate surfaces for days, which could also be the case for SARS-CoV-2 and could pose a prolonged risk of infection¹⁰3.These findings explain the rapid geographic spread of COVID-19, and public health interventions to reduce transmission will provide benefit to mitigate the epiden1ic, as has proved successful in China and several other countries, such as South Korea tJ,iot,io:;_