Tracing the start of COVID-19 in GA

At a time when COVID-19 appears to be receding in much of Georgia, it’s worth revisiting the start of the pandemic in early 2020. Emory virologist Anne Piantadosi and colleagues have a paper in Viral Evolution on the earliest SARS-CoV-2 genetic sequences detected in Georgia. Analyzing relationships between those virus sequences and samples from other states and countries can give us an idea about where the first COVID-19 infections in Georgia came from. We can draw Read more

Reddit as window into opioid withdrawal strategies

Drug abuse researchers are using the social media site Reddit as a window into the experiences of people living with opioid addiction. Abeed Sarker in Emory's Department of Biomedical Informatics has a paper in Clinical Toxicology focusing on the phenomenon of “precipitated withdrawal,” in collaboration with emergency medicine specialists from Penn, Rutgers and Mt Sinai. Precipitated withdrawal is a more intense form of withdrawal that can occur when someone who was using opioids starts medication-assisted treatment Read more

CROI: HIV cure report and ongoing research

The big news out of CROI (Conference on Retroviruses and Opportunistic Infections) was a report of a third person being cured of HIV infection, this time using umbilical cord blood for a hematopoetic stem cell transplant. Emory’s Carlos del Rio gave a nice overview of the achievement for NPR this morning. As del Rio explains, the field of HIV cure research took off over the last decade after Timothy Brown, known as “the Berlin patient,” Read more

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Zika immunology from returned travelers

At the American Association for the Advancement of Science meeting in Boston last weekend, Emory Vaccine Center researcher Mark Mulligan presented some limited findings on immune responses in Zika-infected humans, who were returned US travelers or expatriates.

The results were intriguing, despite the small number of study participants: five, two of whom were pregnant. Detailed information has not been available about immune responses against Zika in humans, especially T cell responses.

Highlights from Mulligan’s abstract:

*All five seemed to have a hole in their immune systems – functional antiviral “killer” CD8 T cells were rare, despite activation of CD8 T cells in general and strong responses from other cell types.

*Cross-reactive immune responses, based on previous exposure to dengue and/or yellow fever vaccine, may have blunted Zika’s peak.

*”Even with prolonged maternal viremia, both pregnancies resulted in live births of apparently healthy babies.” Read more

Posted on by Quinn Eastman in Immunology Leave a comment

Zika virus blindfolds immune alarm cells

Important immune alarm cells — dendritic cells — are fighting Zika virus with an arm tied behind their backs, scientists from Emory Vaccine Center report.

Dendritic cells are “sentinel” cells that alert the rest of the immune system when they detect viral infection. When Zika virus infects them, it shuts down interferon signaling, one route for mustering the antiviral troops. However, another antiviral pathway called RIG-I-like receptor (RLR) signaling is left intact and could be a target for immunity-boosting therapies, the researchers say.

Mehul Suthar, PhD in the lab with graduate students Kendra Quicke and James Bowen

The findings were published on Feb. 2 in PLOS Pathogens.

Zika was known to disrupt interferon signaling, but Emory researchers have observed that it does so in ways that are distinct from other related flaviviruses, such as Dengue virus and West Nile virus. The findings give additional insight into how Zika virus is able to counter human immune defenses. Read more

Posted on by Quinn Eastman in Immunology Leave a comment

How Zika infects the placenta

Zika virus can infect and replicate in immune cells from the placenta, without killing them, scientists have discovered. The finding may explain how the virus can pass through the placenta of a pregnant woman, on its way to infect developing brain cells in her fetus.

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Infected placental macrophages. Zika antigens visible in red. From Quicke et al (2016).

The results were published in Cell Host & Microbe.

“Our results substantiate the limited evidence from pathology case reports,” says senior author Mehul Suthar, PhD, assistant professor of pediatrics at Emory University School of Medicine. “It was known that the virus was getting into the placenta. But little was known about where the virus was replicating and in what cell type.”

Scientists led by Suthar and Emory pediatric infectious disease specialist Rana Chakraborty, MD, found that Zika virus could infect placental macrophages, called Hofbauer cells, in cell culture. The virus could also infect another type of placental cell, called cytotrophoblasts, but only after a couple days delay and not as readily. Other researchers recently reported that syncytiotrophoblasts, a more differentiated type of placental cell than cytotrophoblasts, are resistant to Zika infection.

The cells for the experiments were derived from full-term placentae, obtained from healthy volunteers who delivered by Cesarean section. The level of viral replication varied markedly from donor to donor, which hints that some women’s placentae may be more susceptible to viral infection than others. Read more

Posted on by Quinn Eastman in Immunology Leave a comment