WHAT IS THAT?
Coronaviruses are a very large family of viruses to which strains circulating in animals belong, such as camels, cats and bats, and strains capable of affecting humans. Of the latter, six are known: four caused symptoms similar to those of a cold, while two caused Sars (Severe Acute Respiratory Syndrome), which struck between 2002 and 2003, and Mers (Middle East Respiratory Syndrome) ), which emerged in 2015.
In normal conditionals coronaviruses live perfectly adapted in the organism of wild animals, first of all the bats of the
fruit. To adapt to a very different organism, such as the human one, they have to go through a series of steps, each of which
corresponds to a change in their characteristics. To facilitate this transformation is the encounter with another coronavirus, a similar one that has adapted to an organism other than bats.
For example, in 2002 the civet became the natural laboratory in which the bat coronavirus recombined with that of these small mammals, giving rise to the Sars virus; the virus responsible for the 2009 flu pandemic was a mosaic made up of porcine virus parts, avian virus parts and human virus parts, and by 2015 the Mers virus had gone from bats to camels and then
man. In all cases during these passages the virus changes and along this path it can assume characteristics that allow it to attack man. When this happens the virus has made the so-called "species jump".
The genetic mix born from the encounter of two viruses typical of the animal world generates a virus with receptors that allow it to attack the cells of the human respiratory system.
At the moment the main suspects as a reservoir for the recombination of the coronavirus are two species of snakes and the pangolin, a small mammal similar to an anteater and at risk of extinction and being hunted.
A pangolin (source: Valerius Tygart)
The new virus is indicated with the abbreviation 2019-nCoV , which stands for 'new coronavirus' identified in 2019. Its genetic sequence was quickly completed in China as of January 10 it was published on the Gisaid and Genbank genetic databases, freely accessible to researchers around the world. Since then dozens of genetic sequences have been published. It was a step of fundamental importance because knowing the genetic map of the virus means having valuable indications for developing diagnostic tests and the vaccine. The genetic map also allows to study the virus and even to reproduce it in the laboratory, in whole or in part, as happened in the United States and Italy, at the University of Padua.
Graphical representation of the coronavirus (source: CDC / Alissa Eckert, MS; Dan Higgins, MAM)
HOW IS IT TRANSMITTED?
The 2019 n-CoV virus can also be transmitted by people who, despite already having the infection, do not show symptoms. It emerged from the reconstruction of the first history of contagion within a small family group reported in The Lancet magazine, from which it emerges that a ten year old boy had the virus and had therefore been able to transmit it despite not having the characteristic symptoms infection.
The article published in The Lancet, signed by microbiologists and infectious disease specialists from the University of Shenzen coordinated by Jasper Fuk-Woo Chan actually suggests that "the transmission of the 2019 n-CoV virus from person to person is possible, as well as the diffusion in other cities by means of air flights ". It also notes that rare cases of asymptomatic transmission had also been reported in Sars, the coronavirus infection that emerged in 2002-2003 and that in the case of the 2019 n-CoV virus they could be "a possible source of transmission of the epidemic". For this reason, the authors of the research point out that, "further research on asymptomatic cases would be necessary" and "it is crucial to isolate patients, track and quarantine contacts as soon as possible".
Those published in The Lancet are data confirming that the 2019 n-CoV virus behaves like all other viruses, virologist Ilaria Capua, who at the University of Florida directs the Center of excellence dedicated to 'One', told ANSA Health ', which unifies the themes of human, animal and environmental health. The data, he added, "refer to tests with pharyngeal swabs done in a limited number of patients" and indicate that "one of them was positive for the virus even ten days before the onset of symptoms", while the other more or less one week before: "a normal incubation period for viruses". This, he notes, "confirms that this virus behaves like all other viruses", although "it is obvious that additional data are needed because a study conducted on only six patients has limitations".
2019-nCoV coronavirus particles isolated in a patient (source: NMDC / China CDC)
WHAT ARE THE SYMPTOMS?
Fever and conjunctivitis are the most common symptoms of coronavirus 2019-nCoV infection, while typical symptoms of respiratory diseases, such as cold and cough, can appear later: this is what emerges from the first publication that systematically describes the way where the infection occurs, published in the Journal of the American Medical Association (Jama).
The research was coordinated by Wuhan University, the city where the first cases of infection emerged, and was conducted on 138 patients admitted to Zhongnan hospital. "It is the first comprehensive study that describes symptoms in detail," commented Andrea Crisanti, professor of infectious diseases at the University of Padua.
"Conjunctivitis and redness of the eyes is a collateral manifestation, but quite common," said the expert again referring to the symptoms of the 2019-nCoV coronavirus infection, which is indicated with the acronym Ncip, an acronym that stands for new coronavirus infection pneumonia.
Research published in Jama indicates that fever is the most common symptom, detected in 136 of the 138 patients analyzed, equal to 98.6%); the sense of fatigue was detected in 96 patients (69.6%). Dry cough is less frequent, present in 82 patients (59.4%), followed by muscle pain (48 patients, equal to 34.8%) and breathlessness (43 patients, equal to 31.2%). Much less frequent are headache, dizziness, abdominal pain, diarrhea, nausea and vomiting.
"The data suggest that a rapid transmission of the infection from man to man has occurred", observe the authors of the research, from which it emerges that the transmission rate is equal to 2.2, ie that each person with the Coronavirus infection can infect two more.
Coronavirus (source: CDC)
HOW IS THE DIAGNOSIS MADE?
Thermometer, pharyngeal swab and tests to extract the genetic material of the virus: these are the three stages on which the diagnosis of coronavirus 2019-nCoV infection is based.
The thermometer is the first line, since fever is the most common symptom of infection. It can also be mild and not accompanied by the typical symptoms of respiratory diseases, such as colds and coughs.
The pharyngeal swab is the second stage in the possible diagnosis of the coronavirus and consists in taking samples of fluid from the mucous membrane of the pharynx with the help of a stick at the end of which it finds a cotton swab. The goal is to check whether virus particles are present in the muzzle. "The swab is only a method for removing biological material", explains Andrea Crisanti, professor of infectious diseases of the University of Padua.
The mucus taken by means of the swab is then analyzed to extract the genetic material of the coronavirus. If no trace of the virus is detected, the test is negative, but must be repeated anyway. "A single negative answer - notes Crisanti - is not enough".
Traces of other viruses, such as those responsible for seasonal flu, are also sought in the same sample. "This step is necessary because the symptoms of coronavirus infection are nonspecific": they are very similar, for example, to those of the common flu and tests must be able to discard any hypothesis.
In the event that the test reveals the presence of genetic material of the coronavirus, molecular probes are used to be able to multiply and analyze it.
Graphical representation of the 2019-nCoV coronavirus (source: CDC / Alissa Eckert, MS; Dan Higgins, MAM)
ARE THERE DRUGS AND A VACCINE TO FIGHT IT?
We do everything possible and this at the moment means working on old drugs, born many years ago to fight aggressive viruses such as HIV responsible for AIDS, but a real cure is still far away. Meanwhile, the international vaccine race begins. "In such a critical situation you work with what you have," infectious disease expert Massimo Galli, of the University of Milan and head of the Sacco hospital, told ANSA.
"Currently there are no specific drugs against the new coronavirus and the possibility of using old drugs born to fight other viruses is being tested," continued Galli. This is the case of the combination of drugs announced by Li Lanjuan of the Chinese Commission for Health and Medicine, the latest addition to at least thirty therapies, including antivirals, biologically active natural substances and traditional Chinese medicines. The first drug of the combination, tested only in vitro, is called Abidol and is used against the most common seasonal influenza type A and B viruses; the second is called Darunavir and deactivates the enzyme of the HIV virus called protease, preventing infection. "It must be said, however," said Galli, "that the protease of the HIV virus is very far from that of the coronavirus". In general, he added, the ability of these drugs to act "is modest, but the favorable phenomenon that something works can happen. We try." Administration to humans is still possible because everyone has passed toxicity tests in the past.
In the scientific literature, the expert observed, tests are reported on combinations of old antivirals against the Mers coronavirus, responsible for an epidemic in 2015, "but these are works that have not gone beyond the in vitro tests and on For example, the combination of old anti-HIV drugs, such as lopinavir and ritonavir, both protease inhibitors used against the HIV virus, in association with interferon B has been tried. It is also tried with the chloroquine used so far against malaria.
A phase 3 trial is then underway in China, that is, conducted on a large number of people, to verify the effectiveness of the anti-viral remdesivir, experimented in the past in vitro and in mice against the Ebola and Nipha viruses. Meanwhile, the race for the vaccine continues and, while large and small pharmaceutical companies are organizing, the international collaboration Cepi (Coalition for Epidemic Preparedness Innovations) has set the deadline for presenting projects for February 14: the tender, announced in accordance with the World Health Organization (WHO), is open to companies and research centers.
As for the vaccine, the memory of Sars is still alive, when the vaccine was obtained in a very short time and could not be used because the emergency ended quickly. Having the genetic information at the basis of the new coronavirus available is fundamental, observed Rino Rappuoli, chief scientist and head of external R&D of the GSK vaccine company.
"Since the time of Sars - he added - we know that we must take one of the genes that encode the surface proteins of the virus and su
this basis can start working on a vaccine ". Whether it is vaccines based on recombinant particles, similar to those of the virus but not infectious, or RNA vaccines," the technique to obtain them is very fast, so much so that you can do in a week, "said the expert, noting that technology alone is not enough: the necessary national and international authorizations must be considered.
Among the other techniques to quickly obtain a vaccine, one is the one used against the virus responsible for the Ebola haemorrhagic fever: "you can take a viral vector and insert a synthetic gene of the virus you want to fight inside," he said again Rappuoli. Having the genetic sequence of the virus also means being able to get very specific tools for diagnosis, "which they can
helping to check if the virus is spreading around the world "; knowing the proteins that help the virus to replicate also means" being able to work on specific antiviral drugs "and understanding" if already existing drugs are effective against the virus: this is the first thing to do. "