Science: New crown infected rhesus monkeys recover and no longer infect

the global pandemic of SARS-CoV-2 pneumonia, it is not clear whether patients in recovery are at risk of reintrody. The latest scientific research from China shows that primary neo-coronavirus infection prevents subsequent re-infection, which is important for the prognostic and next vaccine design of new crown patients.
above, published in science, a top international journal, on July 2nd, local time, is entitled "Primary exposure to SARS-CoV-2 protects against reinfection in rhesus macaques". The paper, from the qinchuan
The Chinese Institute of Medical Sciences and the Institute of Experimental Medicine, used a model of rhesus monkeys infected with the new coronavirus.
the research team is from the Chinese Medical
Institute of Medical Animal Experiments and the Department of Radiology at Anzhen Hospital in Beijing, affiliated with Beijing Capital Medical University, and is written by Qin Chuan, director of the Institute of Experimental Animals of Chinese Medicine
Medicine.
Qinchuan team prepared models of rhesus monkeys infected with SARS-CoV-2, with symptoms of interstitific pneumonia and systemic virus transmission, which occurs mainly in the respiratory tract and gastrointestinal tract.
team found that rhesus monkeys re-infected with the same new coronavirus strain did not show detectable viral transmission, clinical manifestations of viral diseases, or pathological changes in tissue during the early recovery phase of the initial neo-crown infection. The researchers compared body fluids and cellular immunity between primary and re-infection of rhesus monkeys and found significantly increased antibody and immune response.
Fact, as early as March 14, qinchuan team published a research paper on biomedically on the preprinted platform bioRxiv, indicating that the infected rhesus monkeys will not develop secondary infections after their recovery.
team believes the results of this study show that initial new crown infections protect against subsequent exposure, which is valuable for the prognosm of the disease and important for vaccine design.
More importantly, the failure of the rhesus monkey model to re-infection suggests that the current discharge of patients "fuyang" can not be due to re-infection, may be due to the previous detection of "false negative" and other reasons.
as early as 2005 and 2014, Qinchuan team has established SARS virus infection and MERS virus infection rhesus monkey model. In this new crown outbreak, Qinchuan team published a number of animal experimental studies of the new coronavirus in the international medical journal, and on April 19 published the results of the first animal experiment of the new coronavirus vaccine, indicating that a purified and inactivated candidate vaccine can provide complete protection for non-human primates, showing positive results in terms of effectiveness and safety.
, it is estimated that about 14% of discharged patients in Guangdong Province and other regions have tested positive again for neoclea nucleic acid after discharge and must return to hospital for observation. The researchers point out that doubts about whether patients are at risk of "relapse" or "re-infection" after recovering from the initial infection have attracted worldwide attention.
therefore, in this study, the researchers used non-human primate models with SARS-CoV-2 infections and then carried out the same virus attack to determine the likelihood of re-infection.The researchers tested four rhesus monkeys for 50 percent of their tissue cell infections, tested their weight, body temperature, lung X-rays, serology and various swab samples, and found that three monkeys lost slightly their body weight seven days after infection, all of which did not observe changes in rectal temperature, and clinical data showed a temporary loss of appetite and increased breathing after vaccination.
the monkeys' nasal and pharynx swabs had the highest viral load three days after infection and then began to drop. Similarly, the swab virus had the highest load on the third day and dropped to an erred level on the 14th day.
To identify the distribution of the new coronavirus in monkeys and changes in tissue pathology, on the 7th day after infection, researchers euthanized and dissected one of the monkeys and found that the virus was widely distributed in the nose, pharynx, lungs, intestines, spinal cord, heart, skeletal muscles and bladder tissue.
In addition, through HE staining and anti-SARS-CoV-2 S protein antibody staining, confirmed that the lesions mainly occur in the lungs, showing symptoms of interstitial pneumonia, characterized by the thickening of the anticulmonary diaphragm, the accumulation of pulmonary macrophages, the deterioration of the epithet of the veins and the penetration of inflammatory cells.
for the remaining three monkeys, the researchers found that their specific antibodies to the new coronavirus increased significantly on the 14th, 21st and 28th days compared to the third and seventh days after infection., the researchers re-infected the remaining monkeys after they recovered. Before re-infection (28 days after initial infection), all three monkeys met the clinical discharge criteria, i.e. no clinical symptoms and chest radiation abnormalities, and two new crown RT-PCR tests were negative.
the researchers treated two of the monkeys (M3 and M4) with the same dose as the initial infection, and the other monkey (M2) as a control group without further treatment. After re-inoculation, the weight of M3 and M4 did not change, and the body temperature increased briefly, but no new coronavirus load was detected in nasal, pharynx and swabs.
five days after re-inoculation, the researchers euthanized and dissected M3 and found no virus replication in all its tissues, and no pathological damage to lung tissue or viral antigens.
(M4) who had not been euthanasia showed no abnormalities. The researchers showed that rhesus monkeys infected with SARS-CoV-2 would no longer be infected with the same strain after recovery, and that the recovered monkeys did not relapse.
previous studies have shown that high levels of neutral antibodies protect against SARS virus infection, but low levels of neutral antibodies are more likely to enhance SARS virus infection and trigger antibody dependence enhancement (ADE). In this study, the researchers found that levels of meso antibodies remained high in monkeys after re-inoculation, and serological evidence showed no ADE effect.
Based on these results, the researchers believe that in the early stages of initial infection, the neutral antibodies produced in monkeys are sufficient to resist the new coronavirus, and accordingly, recovering patients are able to form enough specific antibodies to be immune from re-infection with the new coronavirus.
On the other hand, the researchers did not detect virus replication in all tissues of re-infected monkeys, meaning that SARS-CoV-2 may not remain in the infected person for long, so patients who "relapse" or "re-infected" may be "falsely negative" at the time of testing or meet discharge criteria but do not recover.
that the next step is to improve diagnostic techniques for the lower respiratory tract, patient antibody monitoring and sample testing, which is critical to treating new coronary infections.