Vibrio cholerae phage ICP3 requires O1 antigen for infection

West African-South American pandemic Vibrio cholerae encodes multiple distinct phage defence systems

Our understanding of the factors underlying the evolutionary success of different lineages of pandemic Vibrio cholerae remains incomplete. The West African-South American (WASA) lineage of V. cholerae, responsible for the 1991-2001 Latin American cholera epidemic, is defined by two unique genetic signatures. Here we show that these signatures encode multiple distinct anti-phage defence systems. Firstly, the WASA-1 prophage encodes an abortive-infection system, WonAB, that renders the lineage resistant to the major predatory vibriophage ICP1, which, alongside other phages, is thought to restrict cholera epidemics. Secondly, a unique set of genes on the Vibrio seventh pandemic island II encodes an unusual modification-dependent restriction system targeting phages with modified genomes, and a previously undescribed member of the Shedu defence family that defends against vibriophage X29. We propose that these anti-phage defence systems likely contributed to the success of a major epidemic lineage of the ongoing seventh cholera pandemic.

A Vibrio cholerae anti-phage system depletes nicotinamide adenine dinucleotide to restrict virulent bacteriophages

Bacteria and their predatory viruses (bacteriophages or phages) are in a perpetual molecular arms race. This has led to the evolution of numerous phage defensive systems in bacteria that are still being discovered, as well as numerous ways of interference or circumvention on the part of phages. Here, we identify a unique molecular battle between the classical biotype of Vibrio cholerae and virulent phages ICP1, ICP2, and ICP3. We show that classical biotype strains resist almost all isolates of these phages due to a 25-kb genomic island harboring several putative anti-phage systems. We observed that one of these systems, Nezha, encoding SIR2-like and helicase proteins, inhibited the replication of all three phages. Bacterial SIR2-like enzymes degrade the essential metabolic coenzyme nicotinamide adenine dinucleotide (NAD+), thereby preventing replication of the invading phage. In support of this mechanism, we identified one phage isolate, ICP1_2001, which circumvents Nezha by encoding two putative NAD+ regeneration enzymes. By restoring the NAD+ pool, we hypothesize that this system antagonizes Nezha without directly interacting with its proteins and should be able to antagonize other anti-phage systems that deplete NAD+.IMPORTANCEBacteria and phages are in a perpetual molecular arms race, with bacteria evolving an extensive arsenal of anti-phage systems and phages evolving mechanisms to overcome these systems. This study identifies a previously uncharacterized facet of the arms race between Vibrio cholerae and its phages. We identify an NAD+-depleting anti-phage defensive system called Nezha, potent against three virulent phages. Remarkably, one phage encodes proteins that regenerate NAD+ to counter the effects of Nezha. Without Nezha, the NAD+ regeneration genes are detrimental to the phage. Our study provides new insight into the co-evolutionary dynamics between bacteria and phages and informs the microbial ecology and phage therapy fields.

Sporadic regional re-emergent cholera: a 19th century problem in the 21st century

Cholera, caused by Vibrio cholerae, is a severe diarrheal disease that necessitates prompt diagnosis and effective treatment. This review comprehensively examines various diagnostic methods, from traditional microscopy and culture to advanced nucleic acid testing like polymerase spiral reaction and rapid diagnostic tests, highlighting their advantages and limitations. Additionally, we explore evolving treatment strategies, with a focus on the challenges posed by antibiotic resistance due to the activation of the SOS response pathway in V. cholerae. We discuss promising alternative treatments, including low-pressure plasma sterilization, bacteriophages, and selenium nanoparticles. The paper emphasizes the importance of multidisciplinary approaches combining novel diagnostics and treatments in managing and preventing cholera, a persistent global health challenge. The current re-emergent 7th pandemic of cholera commenced in 1961 and shows no signs of abeyance. This is probably due to the changing genetic profile of V. cholerae concerning bacterial pathogenic toxins. Given this factor, we argue that the disease is effectively re-emergent, particularly in Eastern Mediterranean countries such as Lebanon, Syria, etc. This review considers the history of the current pandemic, the genetics of the causal agent, and current treatment regimes. In conclusion, cholera remains a significant global health challenge that requires prompt diagnosis and effective treatment. Understanding the history, genetics, and current treatments is crucial in effectively addressing this persistent and re-emergent disease.