KATHMANDU — Proteins found in semen increase the spread of Ebola virus infection, according to a study conducted by the University of Pennsylvania.
The study, appeared in the journal Proceedings of the National Academy of Sciences, has claimed that protein fragments, called amyloid fibrils, in human semen significantly increase Ebola virus infection and protect the virus against harsh environmental conditions such as heat and dehydration.
Although Ebola is transmitted primarily through direct contact with blood and other bodily fluids from infected people, follow-up studies from the 2014 epidemic found that men can harbour the virus in their semen for at least two and a half years, with the potential to transmit the virus sexually during that time.
Sexual transmission has also been linked to a resurgence of Ebola in Guinea, which had previously been declared Ebola-free during the West Africa Ebola outbreak. However, the role of host factors involved in sexual transmission has remained poorly understood.
Senior author Paul Bates said, “Sexual transmission of the Ebola virus poses a significant public health concern, especially in light of the ongoing Ebola outbreak in the Democratic Republic of the Congo.”
The researchers suggested that this approach could be tested for its ability to reduce infection in models of Ebola sexual transmission.
Strategies for countering amyloids, such as creating small molecules that disrupt its structure, have been developed to slow or halt HIV transmission.
Several types of amyloids found in semen enhance the transmission and infection of other viruses, such as HIV, by helping the virus attach to the membrane surrounding host cells.
In a previous study, James Shorter, the co-author on the PNAS study, identified how yeast heat shock proteins and a small molecule called CLR01 could disrupt the formation of amyloid fibrils found in semen to make human immune cells less likely to be infected with HIV.
Stephen Bart, the first author of the PNAS study, applied what he learned on the HIV study to investigate the details of sexual transmission of the Ebola virus.
To test the ability of amyloids to enhance infection, benign viruses with the distinctive Ebola glycoprotein (a marker on the outside of the virus particle) were incubated with physiological concentrations of semen amyloids before infecting a variety of human cell types including macrophages, a primary target of Ebola virus in humans.
Infection levels of cells with this benign Ebola virus and amyloids were about 20 times higher compared to cells with the virus alone.
Coauthors Courtney Cohen and John M. Dye found similar results using live Ebola.
The team also found that amyloids enhanced the binding of the virus to cells and increased its ability to be internalized by host cells.
The fibrils working within semen significantly altered the physical properties of the virus, making it better able to survive in internal body environments of high temperature and less moisture.
“Given the potential for sexual transmission to spark new Ebola infection chains, we feel we have found relevant factors that may be important targets for inhibiting the spread of Ebola,” said Bart.
With Agency Inputs
Suicide can’t be predicted by asking about suicidal thoughts : Study
Most people who died of suicide deny they experience suicidal thoughts when asked by doctors in the weeks and months leading up to their death, a major Australian study has found.
The findings, co-authored by clinical psychiatrist and Professor Matthew Large from UNSW’s School of Psychiatry, Sydney that published in the journal BJPsych Open The meta-analysis challenge the widely-held assumption that psychiatrists can predict who will suicide by asking if they are preoccupied with thoughts of killing themselves.
The study showed that 80% of patients who were not undergoing psychiatric treatment and who died of suicide reported not to have suicidal thoughts when asked by their psychiatrist or GP.
“If you meet someone who has suicidal ideation there is a 98 per cent chance that they are not going to suicide,” said Professor Large, an international expert on suicide risk assessment who also works in the emergency department of a major Sydney hospital.
“But what we didn’t know was how frequently people who go on to suicide have denied having suicidal thoughts when asked directly,” he added.
“This study proves we can no longer ration psychiatric care based on the presence of suicidal thoughts alone. We need to provide high-quality, patient-centred care for everyone experiencing mental illness, whether or not they reveal they are experiencing suicidal thoughts,” Professor Large said.
About one in 10 people will have suicidal ideation in their lifetime. But the study showed suicidal ideation alone was not rational grounds for deciding who gets treatment and who does not, Professor Large said.
“We know that suicide feeling is pretty common and that suicide is actually a rare event, even among people with severe mental illness,” Professor Large added.
Suicidal ideation tells us an awful lot about how a person is feeling, their psychological distress, sometimes their diagnosis and their need for treatment but it’s not a meaningful test of future behaviour.
Suicidal feelings can fluctuate rapidly and people may suicide very impulsively after only a short period of suicidal thoughts.
But, people had good reasons not to disclose thoughts of suicide, fearing stigma, triggering over-reactions or upsetting family and friends, and being involuntarily admitted for psychiatric treatment, Professor Large said.
Professor Large emphasized that clinicians should not assume that patients experiencing mental distress without reporting suicidal ideas were not at elevated risk of suicide.