Research Roundup: COVID-19 Immunity and More
Every week there are numerous scientific studies published. Here’s a look at some of the more interesting ones.
Hamster Models of COVID-19 Show Protective Immunity
The jury is still out whether people who had COVID-19 can get it again, but animal studies are suggesting they can’t. A study out of the University of Wisconsin-Madison in hamsters demonstrated that previous infection with SARS-CoV-2 provided protection against getting infected again. And experiments with convalescent serum—using the blood serum from previously infected patients—limited viral replication in the lungs. The research was published in the Proceedings of the National Academy of Sciences and in Science.
“Hamsters are good models for human influenza and SARS-CoV,” said Yoshihiro Kawaoka, professor of pathobiological sciences in the UW School of Veterinary Medicine and a virology professor at the University of Tokyo. “This is why we decided to study them with COVID-19. We wanted to see if the disease course is similar to humans in these animals from beginning to end.”
The study also evaluated infections at both low and high doses, finding that the virus could infect both the upper and lower respiratory tracts. But the key findings were the apparent immunity to reinfection.
“The animals all possessed antibodies and did not get sick again, which suggests they developed protective immunity,” said Pete Halfmann, a research professor in Kawaoka’s U.S. lab. “But we still can’t say how long this protection lasts.”
Changes in Blood Vessels in the Eyes May Predict Alzheimer’s
A study led by researchers at Cedars-Sinai identified early molecular and cellular loss in blood vessels in the retina as well as an accumulation of amyloid-beta in Alzheimer’s patients. The amyloid-protein accumulation is a signature of Alzheimer’s, but the researchers mapped the vascular abnormalities in the retinal blood vessel walls and found that certain regions of the retina were more vulnerable. The study evaluated 62 postmortem eye tissues of 29 patients who had Alzheimer’s, 11 with mild cognitive impairment and 22 with normal cognition. In the Alzheimer’s patient, they found three abnormalities within tiny blood vessels in the retina: high death rates for pericytes; low levels of PDGFRß; and an accumulation of amyloid-beta. The researchers believe this could lead to potentially noninvasive retinal imaging for diagnosing Alzheimer’s years before symptoms develop.
Inherited Mutation in Brazilians Increases Risk of Cancer
Researchers at St. Jude Children's Research Hospital and international colleagues found a variant in the tumor suppressor gene XAF1 that with a TP53-R337H mutation increases cancer risk. The TP53-R337H inherited variant in Brazilians was identified more than 20 years ago. It is rare in the general population, but common in 1 out of every 300 Brazilians. But the mutation itself did not explain the complete cancer risk. But it was a variant in the XAF1 gene in a subset of TP53-R337H mutation carriers that demonstrated a much greater risk of cancer. The research has implications for evaluating cancer risk in Brazilians and for public health evaluations.
Using Light to Treat Cancer
Investigators with Nagoya University are treating a rare form of malignant lung cancer with near-infrared irradiation and a cancer-targeting molecule. The disease is malignant pleural mesothelioma (MPM). It rarely metastasized but is usually diagnosed too late for good treatment options. The group tested the effectiveness of near-infrared photoimmunotherapy (NIR-PIT) along with an antibody linked to a photoabsorber (IR700). When near-infrared light is shone on the part of the body affected by cancer, the compound targets the cancer cell membranes, causing acute cell rupture and tumor death.
Early COVID-19 Infection Rate Possibly 80 Times Greater than Originally Reported
A new research study out of Penn State estimates that the number of early COVID-19 cases in the U.S. were more than 80 times higher and doubled almost twice as fast as originally reported. The research was published in the journal Science Translational Medicine. They focused on the Centers for Disease Control and Prevention’s influenza-like illnesses (ILI) surveillance data for a three-week period in March 2020. They believe that each state’s ILI reporting could not be attributed to the flu and exceeded seasonal baseline levels. They also found that the excess ILI almost perfectly matched the spread of COVID-19 around the country.
“Our results suggest that the overwhelming effects of COVID-19 may have less to do with the virus’ lethality and more to do with how quickly it was able to spread through communities initially,” said Justin Silverman, assistant professor in Penn’s College of Information Sciences and Technology and Department of Medicine. “A lower fatality rate coupled with a higher prevalence of disease and rapid growth of regional epidemics provides an alternative explanation of the large number of deaths and overcrowding of hospitals we have seen in certain areas of the world.”
A Soy Derivative Might Reduce Cognitive Impairment
In a study out of Kyushu University in mice, a protein fragment derived from soy reduced memory degradation in Alzheimer’s mouse models. The molecule is classified as a dipeptide and is the only one known to travel from a mouse’s stomach to its brain intact.
“On top of the possibility of being broken down during digestion, peptides then face the challenge of crossing a highly selective barrier to get from the blood into the brain,” said Toshiro Matsui, professor in the Faculty of Agriculture at Kyushu University and leader of the study published in npj Science of Food. “While our previous studies were the first to identify a dipeptide able to make the journey, our new studies now show that it can actually affect memory in mice.”
Working with colleagues at Fukuoka University, the scientists studied the effect of the dipeptide, named Tyr-Pro, by feeding it to mice for several days before and after dosing them with a chemical often used to simulate Alzheimer’s disease. They tested the mice’s short-term memory using a simple maze and found that the mice who ate the dipeptide over the past two weeks did better than those who did not, although both groups did not run the maze as well as mice without induced memory impairment. Long-term memory tests had similar results.
“We still need studies to see if these benefits carry over to humans, but we hope that this is a step toward functional foods that could help prevent memory degradation or even improve our memories,” Matsui said.