Ticks and bacteria are just a few of the ultra-tiny organisms that Johns Hopkins Medicine scientists are studying to find ways to advance treatments for a range of conditions, including tick-born illnesses, cholera and flesh-eating bacteria infections.

Journalists planning stories around International Microorganism Day on Sept. 17 should contact Alexandria Carolan ([email protected]) or Vanessa Wasta ([email protected]) to connect with the following experts.

Tick-born illnesses

Erin Goley, Ph.D., professor of molecular biology and genetics

Through her research, Erin Goley is hoping to find new ways to target a deadly disease-causing, tick-born pathogen through more effective antibiotics.

Goley studies how bacteria move, grow, divide and multiply. With funding from the National Institutes of Health, Goley and her lab are taking a closer look at the bacterial pathogen Rickettsia parkeri, the microorganism responsible for a tick-borne spotted fever disease usually called R. parkeri rickettsiosis. Rickettsia parkeri is a less virulent but close cousin of the pathogen that causes Rocky Mountain spotted fever.

The condition can rapidly progress into a serious, life-threatening illness, according to the Centers for Disease Control and Prevention. Symptoms may include fever, headache, rash, nausea or vomiting, and early treatment is key to preventing severe illness and death.

In her research, Goley aims to get a better understanding of how Rickettsia parkeri hijack proteins from host cells to move around, spread from cell to cell, and infect other organs in humans after a tick bite.

Light-up bacteria could inform how scientists combat flesh-eating bacteria.

Jonathan Lynch, assistant professor of molecular and comparative pathobiology

How do flesh-eating bacteria find their way to humans from their marine environment?

To explore this, scientist Jonathan Lynch closely observes the relationship between bioluminescent bactera Aliivibrio fischeri and their close relationship with the Hawaiian bobtail squid. Within a few hours after the bobtail squid is born, these bacteria locate the squid and take residence on the squid’s “light organ” as part of a symbiotic relationship that lasts the entirety of the squid’s life.

These light-up bacteria have long tails that they use in a corkscrew-like fashion to swim, and are shaped similarly to Vibrio vulnificus, the so-called “flesh eating bacteria” found in marine environments that can also cause gastroenteritis, or food poisoning.

By seeking to understand how bioluminescent A. fischeri find their way to the Hawaiian bobtail squid, Lynch hopes to define how related bacteria live, move and proliferate. By understanding how these bacteria can infect people, he aims to find more targeted treatments for deadly bacterial diseases.

Bacteria “vaccinate” themselves with dormant viruses

Joshua Modell, associate professor of molecular biology and genetics

Like people, bacteria get invaded by viruses. In a bid to further understand human immunity and develop ways to combat diseases, scientists have sought to learn how these single-cell organisms survive infections by these viruses, known as phages. One versatile line of defense are CRISPR-Cas9 systems, which evolved in bacteria to defend against phages and have been co-opted as powerful gene-editing tools.

With funding, in part, from the National Institutes of Health and National Science Foundation, a team of researchers led by Joshua Modell says they have shed new light on how bacteria protect themselves from certain phage invaders — by seizing genetic material from weakened, dormant phages and using it to “vaccinate” themselves to elicit an immune response.

In their experiments, Modell says Streptococcus pyogenes bacteria (which cause strep throat) take advantage of a class of phages known as temperate phages, which can either kill cells or become dormant. The bacteria steal genetic material from temperate phages during this dormant period and form a biological CRISPR “memory” of the invader that their offspring inherit as the bacteria multiply. Equipped with these memories, the new population can recognize these viruses and fight them off by using Cas9 to cut their DNA.

Scientists pinpoint the construction crew of bacteria cell walls

Jie Xiao, professor of biophysics and biophysical chemistry

Scientist Jie Xiao is working to find new ways to develop more-refined antibiotics that target the enzymes that help build bacteria cell walls, destroying bacteria’s ability to divide and multiply.

With funding, in part, from the National Institutes of Health, Xiao has developed new ways to watch these enzymes’ actions as they are doing their work in live cells, which, she says, has not been possible before.

The outer covering of most cells is a squishy, permeable, double layer of fat molecules that encloses a cell’s gel-like interior and all its parts. But bacteria cells are different. Their outer covering, like plant cells, is closer to a hard shell than a soft covering.

Such rigidity is important to their survival, says Xiao. Bacteria use a rigid outer cell wall to maintain their shape and defend themselves from onslaughts by an organism’s immune system and environment.

Like any structure, cell walls can be broken down and rebuilt. This happens, for example, when bacteria divide and multiply.

A cell divides by breaking down old cell wall material and creating a new wall between the splitting cells. Without a wall, bacteria contents will leak out, and the cell will die.

Scientists, including Xiao, have been piecing together the intricate construction steps of bacteria cell walls in fine detail. The information is critical to understanding the science of bacteria but also has enormous potential for human health.