Biological properties and genetic characteristics of experimental diagnostic Vibrio cholerae bacteriophages

Background. Currently, the researches focused on the design of new diagnostic and preventive preparations based on bacteriophages are underway, so it is importatnt to study the biological properties of cholera phages along with their genetic structure. This information is necessary to predict the phage life cycle and assess the prospects of its practical use in experiments, phagodiagnostics and phagoprophylaxis.Materials and methods. The presence or absence of genes characteristic of temperate bacteriophages was tested using a database created by the authors and developed software "PhageAnalyzer", which allows for rapid analysis of bacteriophage genome-wide sequencing data and prediction of their life cycle.Results and discussion. The morphological structure of experimental diagnostic cholera phages is represented by head bacteriophages of various morphogroups. Negative colonies phage differed in diameter, shape and degree of transparency. No genetic determinants of resistance factors and toxins have been found in the genomes of bacteriophages Rostov-1, Rostov-6, Rostov 7, and Rostov M3. Results of phylogenetic analysis demonstrated that the studied experimental cholera bacteriophages resemble headphages from the genus Vibrio, but are unique, since they lie outside “cluster groups”. Vibrio phages Rostov-1 and Rostov M3 are appeared to be lytic. Genes characteristic of moderate bacteriophages were found in cholera phages Rostov-6 and Rostov 7.Conclusion. The experimental cholera bacteriophage Rostov-1 can be used to differentiate cholera vibrion O1 the serogroup of the El Tor biovar, and Vibrio phage Rostov M3 can be used to differentiate the Classical biovar. Both bacteriophages are lytic and promising components for creating prophylactic drugs against cholera. Vibrio phages Rostov-6 and Rostov 7 can be successfully used only in experimental activities, as well as for monitoring cholera vibrions in the environment. Complete genomic sequences are deposited and available in the international database Genbank (NCBI).

Passive Immunity to Vibrio cholerae O1 Afforded by a Human Monoclonal IgA1 Antibody Expressed in Milk

Background: In cholera epidemics, the spread of disease can easily outpace vaccine control measures. The advent of technologies enabling the expression of recombinant proteins, including antibodies, in the milk of transgenic animals raises the prospect of developing a self-administered and cost-effective monoclonal antibody (MAb)-based prophylactic to reduce the incidence of Vibrio cholerae infection.Methods: We generated a transgenic mouse line in which the heavy and light chain variable regions (Fv) specific for a conserved epitope in the core/lipid A of V. cholerae O1 lipopolysaccharide were expressed as a full-length human dimeric IgA1 (ZAC-3) and secreted into the milk of lactating dams. Milk containing ZAC-3 IgA1 was assessed for the ability to passively protect against experimental cholera infection in a newborn mouse model and to impact bacterial swimming behavior.Results: Newborn mice that were passively administered ZAC-3 IgA1 containing milk, or that suckled on dams expressing ZAC-3 IgA1, were immune to experimental cholera infection, as measured by a reduction of V. cholerae O1 colony forming units recovered from intestinal lysates 12 hours after oral challenge. In vitro analysis revealed that ZAC-3 hIgA1-containing milk arrested V. cholerae motility in soft agar and liquid media and was effective at promoting bacterial agglutination, possibly accounting for the observed reduction in bacterial colonization in vivo.Conclusions: These results demonstrate that consumption of milk-derived antibodies may serve as a strategy to passively protect against cholera and possibly other enteric pathogens.

Detection of Antibodies to Toxin-Coregulated Pili in Sera from Cholera Patients

ABSTRACT Monoclonal antibodies (MAbs) were prepared against toxin-coregulated pili (TCP) isolated from Vibrio cholerae O1 El Tor. Despite their limited bactericidal potential, two MAbs were able to mediate biotype-specific protection against experimental cholera in infant mice. These MAbs were used in immunoblotting studies to assess seroconversion to El Tor TCP following cholera. Clear anti-pilus responses were observed in five of nine patients.