(This is an excerpt of the Health Rounds newsletter, where we present latest medical studies on Tuesdays and Thursdays.)
By Nancy Lapid
May 8 (Reuters) – We also report on a study that reveals why females are more prone to autoimmune diseases.
HUMAN ANTIBODIES AGAINST MEASLES VIRUS IDENTIFIED
For the first time, scientists have identified human antibodies capable of neutralizing the measles virus, which could lead to a new approach for preventing and treating the highly infectious disease.
The antibodies attach themselves to key sites on the measles virus and prevent the virus from entering host cells, according to a report in Cell Host & Microbe.
“These antibodies work as prophylaxis — to protect from initial infection — and they work after viral exposure as a treatment to fight measles infection,” study leader Erica Ollmann Saphire of the La Jolla Institute for Immunology in California said in a statement.
The researchers had previously used an imaging technique called cryo-electron microscopy to capture the first-ever glimpses of how mouse antibodies bind to the measles virus. Those initial studies showed where the measles virus is vulnerable to antibody attack.
In the current study, the researchers isolated measles antibodies from a woman who had been vaccinated against the virus many years earlier. In this volunteer’s blood they found antibodies that bind to two key spots on the virus – the measles fusion protein and an attachment protein called “H” – to inactivate it.
An infusion of the antibodies resulted in a 500-fold lower viral load in a rodent model of measles infection when given either before measles exposure or within 24 to 48 hours after infection, according to the report.
One antibody called 3A12 rendered the circulating virus undetectable, the researchers found.
While more work needs to be done, the researchers see these antibodies as promising tools in the fight against measles. Their new 3D images of the antibody structures provide the materials needed to make the world’s first before- or after-exposure treatment for measles virus, they said.
“Antibodies against the measles virus would be particularly useful in the immunocompromised and people not yet fully vaccinated, including small children too young to be vaccinated,” the researchers wrote.
“These populations currently have no options beyond reliance on herd immunity,” they said.
With increased vaccine skepticism due to misinformation, more communities are falling below vaccination rates needed for herd immunity. The U.S. has reported the highest rate of measles infections in decades.
FEMALES ARE GENETICALLY PREDISPOSED TO AUTOIMMUNE DISEASES
Newly discovered sex-specific differences in the immune system help explain why women are more prone to autoimmune diseases than men, researchers say.
More than 1,000 genetic switches operate differently in female and male immune cells, driving higher overall activity of inflammatory pathways in females, the researchers reported in The American Journal of Human Genetics.
In autoimmune diseases – such as lupus, multiple sclerosis, and rheumatoid arthritis – the immune system mistakenly attacks the body’s own healthy cells, resulting in chronic inflammation, tissue damage, and impairment of joints, skin, and organs.
The researchers analyzed more than 1.25 million immune cells circulating in the blood from nearly 1,000 healthy individuals in Australia. Using technology that allowed cell-by-cell analyses, they spotted sex-specific genetic variations that had been missed by previous “bulk” studies that measured average immune activity across a whole mixture of cells.
In particular, the researchers investigated genetic switches that are active in one sex but not the other – so-called ‘expression quantitative trait loci’ – that act like volume dials controlling how strongly a gene is turned on or off.
In females, genetic activity was heavily skewed toward inflammatory pathways, with higher levels of immune cells called B cells and regulatory T cells, they found.
In males, genetic activity was more concentrated on basic cellular maintenance and protein-building functions, with higher proportions of monocytes, cells that act as first immune responders.
“While this highly reactive immune profile gives females an advantage in fighting viral infections, it comes with a biological trade-off: a greater predisposition to autoimmune diseases,” senior study author Dr. Sara Ballouz of the University of New South Wales said in a statement. Male immune cells are less primed for inflammation, making men generally more susceptible to infections, she added.
“Our findings show that the immune system needs to be studied with sex in mind,” study leader Dr. Seyhan Yazar of Garvan Institute of Medical Research said in a statement.
“Even though we know men’s and women’s immune systems differ, many studies still overlook these differences, which can limit how well we understand disease, and in turn bias treatment options.”
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(Reporting by Nancy Lapid; Editing by Bill Berkrot)
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