Vibrio cholerae is a young-looking vibrion of gentle nature, and one of the core members of the Vibrio genus. He lived with his big brother in the ocean for most of his life, before meeting Yersinia pestis and his friends. Originally, Cholerae is not a pathogen; he became one after encountering a bacteriophage, CTXφ, thus acquiring the Cholera toxin (CTX)1,2,3. CTX-holding Cholerae strains are feared for unpredictable mood swings that are hard to quell. Cholerae owns at least Type 24, and Type 6, Secretion Systems3,5.
Throughout History, Cholerae caused
Background
Growing up in the ocean, Cholerae was surrounded by the other Vibrio. The Vibrio like to have fun, party, and are quite easy-going. Early on, Cholerae was noticeably shier than the rest; he was like a little brother figure to other members of the genus. Vibrio harveyi in particular, head of the Vibrionaceae, adored Cholerae as such. But, in light of his own eclectic nature, Harveyi felt he couldn’t adequately take care of Cholerae. So, he decided to put him in Vibrio vulnificus’s care, the both of them being less extroverted than the others.
It turned out Vulnificus and Cholerae didn’t get along. Cholerae was sensitive in a way that Vulnificus wasn’t. Vulnificus often insisted Cholerae learned to defend himself, something Cholerae didn’t feel up to. This often led to the former belittleling the latter. Later, the Vibrionaceae suffered a great internal crisis, leaving Cholerae feeling left out, already burned out by Vulnificus’s attitude towards him. Without telling anyone, he started searching the waters for new horizons.
As Cholerae wandered farther away from what he knew, he found himself a prey to a bacteriophage, CTXφ. As a lysogenic phage, CTXφ took the opportunity to sneak into Cholerae’s genome, making CTXφ a prophage and Cholerae his long-term host. The trauma from the event left Cholerae mentally unwell, and desperate to find somewhere safe again.
Soon after, a young Yersinia pestis found and exhausted Cholerae near freshwaters, and decided to help him out. Pestis immediately took a liking to him, and introduced him to his dearest friends, like Mycobacterium tuberculosis. When Cholerae incidentally tapped into his pathogenic potential, his new friends were amazed, and he finally felt like he belonged somewhere.
All this time, non-CTX Cholerae, still living in the seas, was acting as though nothing was happening. By then, the Vibrio internal situation had subsided. But, with word of mouth spreading about Cholerae’s feats of pathogeny, the Vibrio eventually found out about his desertation of the seas. Harveyi blamed himself for not looking after Cholerae himself, and their relationship improved. But Vulnificus was furious about Cholerae’s preference for land. Despite having his secret uncovered, for a long time, Cholerae lived happily between land and sea.
Things started to fall apart around the 19th century. With he and his friends being tailed by human advances in medicine, and Pestis being unsuccessful in his final pandemic, things were looking grim. Though Cholerae tried his best, he felt like he was losing his home life again. Nowadays, Cholerae is the moodiest he’s ever been, though he still finds nostalgic solace in the waters.
Personality
Deep down, and despite everything he went through, Cholerae’s heart remains sweet, trusting, and extremely sensitive. He is naturally curious, open-minded, and overly empathetic. Be it his own feelings or other’s, he feels every emotion intensely. He internalises things very deeply. He’s a selfless friend, with a strong moral compass.
Though he’d rather not be in the spotlight, CTX-free strains are approcheable and easy to get along with. CTX-free Cholerae tends to live in his own head. He can be very naive, which is why his big brothers make sure to look after him well. He likes having people around, but he’d rather not be in a crowd. Though cowardly, he will take a stand when he’s able to help someone in difficulty. He will happily give, without expecting anything in return. CTX-free Cholerae will put his friends above anything else. Once someone has his loyalty, it’ll last a lifetime.
CTX-holding Cholerae is something else. Though he can sometimes behave similarly to his CTX-free self, he is easily disturbed, and things can quickly take a turn for the worst. CTX-holding Cholerae gets paranoid on the regular, especially so with strangers. When convinced of something, no matter why, it is near impossible to persuade him otherwise. He gets impatient and loses his nerves easily, holds grudges… A CTX strain is prone to bouts of (perceived) injustice-fueled anger, which can prove devastating, and it usually doesn’t amount to anything to try to get in his way then. His next moves are hard to predict, as it’s unclear what goes on in his head. Deep down, Cholerae’s anger stems from long-lasting anxiety and emotional trauma. El Tor strains get the carried away the most in how violent they get to others.
Relationships
CTXφ
Phage infections can be completely asymptomatic to bacteria, just like they can be life-changing. Little is known about CTXφ as an entity. At first, the relationship between them and Cholerae was very conflictual. Eventually they learned to tolerate, and work with, one another.
As CTXφ lives as DNA in some Cholerae strains’ genome, they technically share a consciousness. CTXφ’s sole presence is a key player in making a Cholerae strain emotionally unstable, and their mood has a great influence on his. CTXφ knows what Cholerae is thinking, and feeling, at all times, but the reverse is not always true.
Since CTXφ rarely chooses to kill Cholerae cells to live as a virion again, they mostly exist as a voice Cholerae hears in his head. CTXφ, more often than not, manifests as intrusive thoughts, though they can also hold full on conversations. After having coexisted together for so long, this relationship made Cholerae more curious and open about meeting virions than the average bacterium.
Land-dwelling bacteria
(Disclaimer: some bacteria in this section can be found in seawater, but it’s not their primary habitat.)
Deinococcus radiodurans
Cholerae is scared of Radiodurans, because he’s the only person beside CTXφ able to talk to him directly in his mind. Beside that, he knows that Radiodurans is not a menace – quite the opposite –, but his presence remains somewhat unsettling. Radiodurans might be the only person able to uncloud Cholerae’s heart in a fit of madness.
Mycobacterium tuberculosis
Despite both being close friends to Pestis, Cholerae never really felt close to Tuberculosis. Though they have things in common on paper, Tuberculosis’ constant state of melancholy following his clash with Pestis drew Cholerae away, and they never really sympathised on a deeper level. If anything, Cholerae doesn’t really like how close Tuberculosis is to Pestis.
Pseudomonas aeruginosa
Both being pathogenic water cruisers, it was only natural that Cholerae would meet Aeruginosa sooner or later on his freshwater adventures. Like others, Cholerae was hit by Aeruginosa’s charm right away, and feels very intimidated having him around. He’d love to get closer to him, but despite Aeruginosa’s warm personnality, it feels very daunting.
Yersinia pestis
Pestis is one of Cholerae’s best friends. Though they grew up in very different places, they could relate to each other right away, probably because they are both “little brother” figures to their respective genera. Cholerae likes how energetic and determined Pestis can be, and Pestis can relate to Cholerae’s withdrawn side as well. They know they can always count on each other, even at their worst. Cholerae couldn’t be angry with him, even if there was ground to be.
Sea-dwelling bacteria
Vibrio harveyi
Cholerae loves Harveyi as his older brother. For a long time, he admired him from afar as a lead figure in the Vibrionaceae family, but feared he would disappoint him by looking for life on land. After Cholerae’s new life leaked, they had an honest talk, and their relationship got better than ever. Cholerae’s now confident that he can tell Harveyi anything.
Vibrio vulnificus
Vulnificus is the closest thing Cholerae’s had to an actual older brother. Sadly, their relationship was never good to begin with, and it did not improve later. Though both are different from the rest, in that they are not as extroverted as other Vibrio’s, Cholerae and Vulnificus have always been on different wavelengths from each other as well. Cholerae is dreamier and Vulnificus more pragmatic. Cholerae remains scared of being alone with Vulnificus, even though Vulnificus was never physically violent towards him. He fears his reactions and doesn’t feel like he can confide in him.
Shewanella oneidensis
Cholerae likes Oneidensis, because he reminds him of other Vibrio’s. He’s also heard that Oneidensis and Harveyi are really good friends. Still, Cholerae finds Oneidensis a bit weird most of the time, but it doesn’t put him off, because he can feel that’s his way of showing authenticity.
Trivia
- Cholerae has a lesser-known twin brother, Vibrio mimicus1,6.
- His T6SS looks like a trident, similarly to Harveyi’s. Cholerae uses it to kill gut microbiome residents and colonise the gut more efficiently 3.
- All strains speak with a stutter. It can worsen depending on mood.
- Because of his relationship to CTXφ, he is quite curious about virions and virus biology.
- Non-pathogenic Cholerae can be found inhabiting some of the phyto- and zooplankton 7.
- Just like other species of the Vibrio genus, some environmental Cholerae strains are bioluminescent 8.