Drug Sensitivity of Vaccine-Derived Rubella Viruses and Quasispecies Evolution in Granulomatous Lesions of Two Ataxia-Telangiectasia Patients Treated with Nitazoxanide.

Raeesa Faisthalab,Ludmila Perelygina,Joseph Icenogle,Morna Dorsey,Suganthi Suppiah,Kathleen E Sullivan

doi:10.3390/pathogens11030338

Abstract

A strong association between rubella virus (RuV) and chronic granulomas, in individuals with inborn errors of immunity, has been recently established. Both the RA27/3 vaccine and wild-type RuV strains were highly sensitive to a broad-spectrum antiviral drug, nitazoxanide (NTZ), in vitro. However, NTZ treatment, used as a salvage therapy, resulted in little or no improvements of RuV-associated cutaneous granulomas in patients. Here, we report investigations of possible causes of treatment failures in two ataxia-telangiectasia patients. Although a reduction in RuV RNA in skin lesions was detected by real-time RT-PCR, live immunodeficiency-related vaccine-derived rubella viruses (iVDRV) were recovered from granulomas, before and after the treatments. Tizoxanide, an active NTZ metabolite, inhibited replications of all iVDRVs in cultured A549 cells, but the 50% and 90% inhibitory concentrations were 10–40 times higher than those for the RA27/3 strain. There were no substantial differences in iVDRV sensitivities, neither before nor after treatments. Analysis of quasispecies in the E1 gene, a suspected NTZ target, showed no effect of NTZ treatments on quasispecies’ complexity in lesions. Thus, failures of NTZ therapies were likely due to low sensitivities of iVDRVs to the drug, and not related to the emergence of resistance, following long-term NTZ treatments.

Highlights

Rubella virus (RuV, the family Matonaviridae, genus Rubivirus) is known to cause asymptomatic or mild infections that are quickly resolved in immunologically competent individuals [1,2]
We demonstrated that failure to achieve granuloma resolution was associated with continuous presence of both immunodeficiency-related vaccinederived rubella viruses (iVDRV) RNA, albeit in reduced quantities, and infectious iVDRVs
Half of the CA RVi clones were identical in T0 and T1 skin samples, suggesting RVi quasispecies diversity did not change after NTZ treatment of the CA patient (Figure 5C)

Summary

Introduction

Rubella virus (RuV, the family Matonaviridae, genus Rubivirus) is known to cause asymptomatic or mild infections that are quickly resolved in immunologically competent individuals [1,2]. RuV can establish persistent infections in fetuses and immune-privileged body sites, and cause substantial pathologies, such as congenital rubella syndrome (CRS), post-rubella encephalitis, arthritis, or Fuchs’ uveitis [3]. While successful vaccination campaigns, using live attenuated RuV vaccines have eliminated rubella and CRS in the Americas, and many countries worldwide, there are people with underlying conditions who are not recommended for vaccination, as they may exhibit adverse reactions [4,5]. One such population is patients with inborn errors of immunity (IEI). There is strong evidence that the RuV vaccine can establish persistent infections in IEI patients and plays a role in granuloma development [9–11]. The iVDRVs persisted in granulomatous lesions, as a diverse population of closely related quasispecies [12]

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Conclusion