167 views | Akanimo Sampson | August 15, 2020
An Africa-wide study of antibodies to the coronavirus has begun. Already, evidence from a smaller study is indicating that many more people have been infected than official numbers show.
While this came from the Africa Centers for Disease Control and Prevention on Thursday, University of Otago researchers have learnt more about how viruses operate and can evade the immune system and are now using their discovery to help learn more about COVID-19.
The recent research, led by Dr. Mihnea Bostina and PhD student Sai Velamoor from the Department of Microbiology and Immunology and Otago Micro and Nano Imaging, Electron Microscopy, specifically looked at the Oryctes rhinoceros nudivirus (OrNV) virus, an important bio-control agent against the coconut rhinoceros beetle, a devastating pest for coconut and oil palm trees in Southeast Asia and the Pacific Islands.
The Otago scientists found the virus used a “decoy” strategy to evade the immune system. Dr. Bostina explains the findings are a small step in the bid to better understand infectious disease.
The research team is now using the same technique to investigate changes in cells infected with SARS-CoV-2, the coronavirus that causes COVID-19.
“We have used the same technique to investigate changes in cells infected with SARS-CoV-2 and are continuing work in this area.”
Dr. Bostina explains that viruses that replicate and assemble inside the nucleus have evolved special approaches to modify the nuclear landscape for their advantage.
The research team used electron microscopy to investigate cellular changes occurring during nudivirus infection and found a unique mechanism for how the virus works.
“Our study revealed that the virus acquires a membrane inside the nucleus of the infected cell and it gets fully equipped to infect new cells at this precise location. This is in contrast with other enveloped viruses—like coronavirus, which is also an enveloped virus—which derive their membranes from other cellular compartments.
“After it gets fully assembled, the virus uses a clever tactic of passing through different environments, packed inside various membrane structures until it gets released at the cellular membrane.”
Ms Velamoor says this strategy implies that many of the viruses released by the infected cells will be enclosed in a cellular membrane while travelling inside the infected organism.
“This means they will be missed by the immune system and they can use this membrane decoy to penetrate any other type of cells, without the need of a virus-specific receptor.
“It shows for the very first time a clever strategy available to insect viruses. It will be interesting to find in what measure other types of viruses—like the ones infecting humans—are also capable of carrying out a similar process.”
Dr. Bostina says the research demonstrates another manner in which viruses are capable of hijacking infected cells and alerts scientists to the novel mechanism of viral transmission.
“Viruses will never cease to amaze us with their indefatigable arsenal of tricks. Only by studying them can we be prepared to adequately respond when they infect us.”
The research has just been published in mBio, a science journal published by the American Society for Microbiology.
However, experts are eager to know the real number of COVID-19 cases in Africa, as confirmed cases and deaths have been relatively low on the continent of 1.3 billion people. Poor data collection, however, has complicated efforts.
But recent surveys in Mozambique found antibodies- proteins the body makes when an infection occurs—to the virus in 5% of households in the city of Nampula and 2.5% in the city of Pemba. That’s while Mozambique has just 2,481 confirmed virus cases. Further studies are underway in the capital, Maputo, and the city of Quelimane.
“What is important is far fewer people are coming down with the disease,” Africa CDC director John Nkengasong told reporters. “How many people are infected and asymptomatic on our continent? We don’t know that.”
Africa’s young population, with a median age of 19, has been called a possible factor.
The new continent-wide antibodies study will include all African countries, but the ones showing interest to start in the coming weeks are Liberia, Sierra Leone, Zambia, Zimbabwe, Cameroon, Nigeria and Morocco, Nkengasong said.
The African continent reached the milestone of one million confirmed cases last week, while global health experts have told The Associated Press the true number is estimated to be several times that. More than 24,000 deaths have been confirmed, and the case fatality rate is 2.2%.
The Mozambique antibodies surveys detected the virus in all neighbourhoods in Nampula and Pemba, National Institute of Health director Ilesh Jani told reporters.
The groups with the highest exposure to the virus were market vendors at 10%, followed by health professionals at between 5.5% and 7%, police at between 3.7% and 6% and shop and other business employees at between 5% and 5.5%.
“We don’t know why more are not being hospitalised”, Jani said. “In Nampula we thought we would see more mortality” but there has been no increase in deaths.
He wondered whether the low death rate will continue or whether the disease “is going to become more aggressive.”
In a separate survey, researchers in Kenya who tested more than 3,000 blood donors have said one in 20 people there could have antibodies to the virus. The country has more than 28,000 confirmed cases.
But the Africa CDC director warned, “The sampling was not a very systematic sampling and we should interpret that with care.”
Nkengasong also said the Africa CDC has not been in touch with Russia about its reported vaccine for COVID-19 announced this week. African health authorities want to make sure that any virus intervention they pursue “is backed by good science”, he said, adding that “we are open to all partnerships.”