Long-term in vitro exposure of Treponema pallidum to sub-bactericidal doxycycline did not induce resistance: Implications for doxy-PEP and syphilis.

Doxycycline post-exposure prophylaxis (doxy-PEP) could significantly reduce syphilis incidence. However, the increase in intermittent doxycycline usage might select resistant Treponema pallidum (T. pallidum) strains. To assess whether resistance to doxycycline could be induced in this pathogen, we exposed the SS14 strain in vitro both intermittently and continuously to a sub-bactericidal doxycycline concentration that still exerts antibiotic pressure. During and after each exposure experiment, we assessed the doxycycline minimal inhibitory concentration in test and control treponemes and performed whole genome sequencing, concluding that no resistance developed. This work suggests that doxycycline-resistant T. pallidum is not an immediate threat for doxy-PEP implementation.

Long-term in vitro exposure of Treponema pallidum to sub-bactericidal doxycycline did not induce resistance: Implications for doxy-PEP and syphilis.

Doxycycline post-exposure prophylaxis (doxy-PEP) could significantly reduce syphilis incidence. However, the increase in intermittent doxycycline usage might select resistant Treponema pallidum ( T. pallidum ) strains. To assess whether resistance to doxycycline could be induced in this pathogen, we exposed the SS14 strain in vitro both intermittently and continuously to a sub-bactericidal doxycycline concentration that still exerts antibiotic pressure. During and after each exposure experiment, we assessed the doxycycline minimal inhibitory concentration in test and control treponemes and performed whole genome sequencing, concluding that no resistance developed. This work suggests that doxycycline-resistant T. pallidum is not an immediate threat for doxy-PEP implementation.

A high-throughput, polymerase-targeted RT-PCR for broad detection of mammalian filoviruses.

Filoviruses are some of the most lethal viruses in the modern world, and increasing numbers of filovirus species and genera have been discovered in recent years. Despite the potential severity of filovirus outbreaks in the human population, comparably few sensitive pan-filovirus RT-PCR assays have been described that might facilitate early detection and prevention. Here, we present a new pan-filovirus RT-PCR assay targeting the L polymerase gene for detection of all known mammalian filoviruses. We demonstrate the detection of 10 synthetic filovirus RNA templates with analytical sensitivity ranging from 178 to 3,354 copies/mL, without cross-reactivity on 10 non-filoviral human viral species. We verified assay performance on 10 inactivated filovirus isolates, yielding initial sensitivities of 0.012-44.17 TCID50/mL. We coupled this broadly reactive RT-PCR with a deep sequencing workflow that is amenable to high-throughput pooling to maximize detection and discovery potential. In summary, this pan-filovirus RT-PCR assay targets the most conserved filovirus gene, offers the widest breadth of coverage to date, and may help in the detection and discovery of novel filoviruses.IMPORTANCEFiloviruses remain some of the most mysterious viruses known to the world, with extremely high lethality rates and significant pandemic potential. Yet comparably few filovirus species and genera have been discovered to date and questions surround the definitive host species for zoonotic infections. Here, we describe a novel broadly reactive RT-PCR assay targeting the conserved L polymerase gene for high-throughput screening for filoviruses in a variety of clinical and environmental specimens. We demonstrate the assay can detect all known mammalian filoviruses and determine the sensitivity and specificity of the assay on synthetic RNA sequences, inactivated filovirus isolates, and non-filoviral species.