Evolutionary dynamics and geographical dispersal of Borrelia lusitaniae

Background

Borrelia lusitaniae is a species within the complex Borrelia burgdorferi sensu lato, associated with lizards as reservoirs and Ixodes ricinus as its main vector. Borrelia lusitaniae is predominantly distributed in Central and Southeast Europe, and in countries of the Mediterranean basin, such as Portugal, Morocco, Tunisia, and Italy where this spirochete appears to infect vector ticks more frequently than other genospecies. Evolution of this zoonotic tick-borne microparasite is shaped by different environmental factors. Comprehensive phylogenetic analysis may give insight into how B. lusitaniae spreads to new geographic locations.

Aim

We applied Bayesian statistical methods to B. lusitaniae multilocus sequence typing (MLST) data to study the migration routes of B. lusitaniae and its potential for further spread.

Results

The discrete phylogeographic analysis placed origins of B. lusitaniae in Southeast Europe and identified at least two introductions of B. lusitaniae from Europe to North Africa. Estimated effective reproductive potential (Re), as a key indicator for a pathogen spread, suggested potential for further spread.

Conclusion

The results of this study can provide beneficial information about the potential for further spread of B. lusitaniae in Europe and North Africa and estimation of necessity for the development of strategies to monitor and control Lyme borreliosis.

Hepatitis B virus in tissue culture systems. I. Serial propagation of virus in human macrophages

Human peritoneal macrophages, originating from peritoneal dialysis fluid and growing in vitro, support the growth and serial propagation of hepatitis B virus (HBV). The evidence for virus growth is based on the regular detection of HB core antigen in twenty-one passages of macrophages by a complement fixation test using rabbit anti-HB core serum; detection of HB core and e antigen in the twenty-first passage, using an enzyme-linked immunosorbent assay; the detection of HB antigen in cultured macrophages in the fourteenth passage by an indirect immunofluorescence test using human convalescent serum; and detection of HB core antigen in the twenty-second passage by immunofluorescence test using rabbit anti-HB core serum. No CPE was observed through twenty-one passages. It is believed that this is the first successful cultivation and serial propagation of HBV in a cell culture system in vitro. Practical aspects of this finding are discussed.