Appearing abroad with delta and Omikeron ligature virus? This may just be a "oolong"

According to cyprus post on January 8, 2022, scientists in the country announced the discovery of a recombinant NEW CORONAVIRUS strain of Delta and Omiljung in the local community, which is genetically closer to the Delta strain but has a large number of unique variants of the Omiljun strain. Researchers at the University of Cyprus named it "Deltacron".

The report also said that local sequencing found that 25 people were infected with Delta Kerong, of which 14 were hospitalized. However, whether the strain is more pathogenic and contagious remains to be seen. Rayondy Cos regis, a member of the President's Scientific Advisory Committee on COVID-19 of the Republic of Cyprus, said that Delta Kerong is more common among hospitalized patients than unpatients.

The report immediately attracted a lot of attention at the time of the delta and Omicron epidemic, but the study's conclusions were also controversial to some extent. Virology expert Chang Rongshan believes that this is the "oolong" of molecular epidemiologists at the University of Cyprus in the biological informatics analysis of the two variant strains in the sample.

Specifically, if samples of several organ origins are mixed at the time of sampling, "oolongs" may occur. For example, if delta is infected in lung tissue and Omilon is infected in the nasal cavity, and mixing two samples and then extracting RNA and sequencing it will be mistaken for two strains of recombination, in fact, only the two viruses jointly infect the same person.

Therefore, it is necessary to sample the patient's different organs, such as the brain, reproductive system, upper respiratory tract, lungs, intestines and other parts, and perform RNA extraction and sequencing alone to confirm whether it is infected with a new recombinant variant strain.

Chang Rongshan said that the current technical means can easily determine whether a patient is infected with DNA and RNA viruses at the same time, such as hepatitis B is a DNA virus, hepatitis C is an RNA virus, and PCR testing is easy to determine whether the patient is co-infected with these two viruses.

However, if a patient is infected with several RNA viruses at the same time, it puts forward higher requirements for detection technology, such as monitoring Omilon and Delta, sampling different tissues or organs separately, extracting viral RNA and then retrotranscribing into DNA and then sequencing, and strictly preventing contamination during the process.

When extracting RNA samples, the nucleic acids of the 2 mutants are often mixed together and difficult to separate, in which case all or part of the mutation sites of the 2 variants will be found in the "inaccurate whole genome" spliced out after sequencing.

However, there are still ways to separate the 2 mutants when the gene fragments are spliced, but the abundance of the 2 mutants often varies greatly, and it takes a long time to separate them technically, and if the analysis is not enough, it will be concluded that "the genes of Delta Kerong are closer to the Delta strain, but have a large number of unique variations of the Omicron strain", as the Cypriot scientists said. And this is actually the illusion that Delta is the dominant strain in the sample, and the low abundance of Omikeron,

In addition, it is worth mentioning that Chang Rongshan said that there is a fierce competitive relationship between the new crown mutant strains. At present, the global situation is that the more evolutionary advantage of the Omikeron variant strain is rapidly PKing out the Delta variant, while the previous major variants have almost all been PK out by these two strains.

He believes that Omikeron has now won in England. According to the UK Health Security Agency (UKHSA), Delta's proportion of confirmed COVID-19 cases is close to 0%. "From the perspective of biological evolution, the Amikharon and Delta viruses are incompatible with fire and water, and will only replace, not recombine." Chang Rongshan said.

However, although "Delta Kerong" will not appear, a single case may also be infected with both Omicron and Delta.

Taking the cold as an example, Chang Rongshan introduced that there are four kinds of weak coronaviruses that only cause the common cold in the population, if it is a cold in which the weak coronavirus participates, generally only one virus will be found in each cold person, but sometimes two viruses will be found, and there are often a variety of different viruses that infect a person's respiratory tract infection at the same time, such as adenovirus and influenza viruses infecting a person at the same time, which can be called mixed infection.

Previously, there have been cases of simultaneous infection with the new crown and influenza in foreign countries, so it is not uncommon but not uncommon to find different subtypes of a virus, or different variants, in the same person.

In addition, the claim of "Deltakron" has also been widely questioned, including BY WHO experts.

According to an update by the Cyprus Post on January 9, Thomas Peacock, a virologist in the COVID-19 response expert group at Imperial College London in the United Kingdom, said that the "Delta Kerong" variant strain discovered by Cypriot researchers is likely due to the contamination of the sequence. "True recombinants often don't appear until weeks or even months after the two viruses coexist in large numbers, and Omilon doesn't appear for a few weeks." Peacock explains.

Greek virologist Dr. Gkikas Magiorkinis, as well as members of the Greek scientific team, also posted on social media that, according to their independent analysis, this was a technical error in the process of reading the genome in the laboratory. KUPARI, a member of the WHO COVID-19 team, and Van Kelkhofer, technical leader of the WHO Health Emergency Programme, also posted on social media that there is no Deltakron strain, and it is likely that the laboratory was contaminated during the sequencing process, and the specimen of the Delta strain was mixed with the Olmikerron strain.

Reporter | Yuan Yiming

Edit | Xie Xin