Chinese research with monkeys indicates that animals that have already been infected with SARS-Cov-2, the new coronavirus, are more resistant to reinfection.
A study by the Institute of Animal Science Laboratory of the Chinese Academy of Medical Sciences revealed that monkeys infected with SARS-Cov-2, the new coronavirus, may have greater resistance against the virus at a later exposure. According to experts, reinfection did not occur in monkeys that produced the neutralizing antibody in the initial stage after the first infection.
The scientists observed body weight, temperature and viral loads in the throat and anus of four Rhesus monkeys that inoculated a 50% dose of the coronavirus that caused Covid-19 through the airways. Of these, three lost weight and had other clinical symptoms. However, viral loads in all monkeys suffered a natural decline after reaching the climax on the third day. Meanwhile, the number of antibodies has steadily increased over the next few weeks.
In the next step of the study, the researchers dissected one of the four monkeys to understand the replication and distribution of the virus, in addition to continuously monitoring the other three. Twenty-eight days after primary infection, the three monkeys were considered to have recovered, as the symptoms reduced in intensity and the antibody was tested positive.
After that, two of the three monkeys were inoculated again with the same dose of SARS-CoV-2. Finally, it was discovered that no viral loads or viral replication were found in re-exposed monkeys.
This study is important, since the antibody used in the neutralization found in the test on animals is comparable to that of recovered patients, this finding will have important implications for the development of a vaccine.
According to the researchers, reinfection is unlikely. What can occur are tests not performed properly or a long duration of the disease. “Several factors can make the test results inaccurate, including the quality of the test kit and the way the sample was collected and stored,” said Professor Jin Dong-yan, a molecular virologist at Li Ka Shing School of Medicine from The University of Hong Kong to the South China Morning Post.
In a statement to the Los Angeles Times, Clifford Lane, deputy director of Clinical Research and Special Projects at the National Institute of Allergy and Infectious Diseases, stated that the ideal way to prove that reinfection occurred is to sequence the genomes of the initial and subsequent viruses that circulate in a patient. If they are not identical, it suggests that the virus has mutated enough to avoid the patient’s antibodies and cause a second infection.
Thus, the researchers suggest that further improvements in diagnostic techniques, antibody monitoring and testing of lower respiratory tract samples are essential to cure SARS-CoV-2 infection.