Drug resistance remains a global challenge in the fight against the HIV pandemic [1,2].
Where feasible, guidelines recommend testing for HIV drug resistance before initiation
of and upon inadequate response to antiretroviral therapy in order to guide regimen
selection [3,4]. Where less available, such testing is recommended only in specific
populations and circumstances [5], and where even less accessible, it is recommended
only for public health surveillance [6]. Sanger sequencing, available since the 1970s
[7], has been the conventional technology used for HIV drug resistance testing [3,8].
Essential external quality assurance (EQA) strategies, needed to ensure reliable results
of complex Sanger sequencing-based HIV drug resistance testing assays, have supported
laboratories for decades [9,10,11,12]. More recently introduced next generation sequencing
(NGS) technologies are increasingly used in diverse circumstances, including for HIV
drug resistance testing [13,14]. Whether these technologies can and should replace
Sanger sequencing for HIV drug resistance testing, and if so, in which settings and
circumstances, is unclear. In that context, validated EQA strategies to support laboratories
using NGS for HIV drug resistance testing are essential, due to more complex NGS-based
methods, yet such strategies remain to be established. Developing such EQA strategies,
as well as more standardized laboratory- and bioinformatics-related considerations,
are important early steps towards widespread implementation of NGS for HIV drug resistance
testing [15,16,17].
In February 2018, an international symposium on bioinformatic strategies for NGS-based
HIV drug resistance testing was held in Winnipeg, Canada. Outcomes of the symposium
included proposed standardizations of NGS data processing, quality control, and reporting
and management strategies for HIV drug resistance testing. The intent was for these
standardizations to serve as a starting guideline for NGS HIV drug resistance data
processing that informs the refinement of existing pipelines and those yet to be developed
[18].
In September 2019, the Second International Symposium on NGS HIV Drug Resistance was
held in Winnipeg, Canada, to focus on EQA strategies for NGS-based HIV drug resistance
testing. Symposium deliberations emphasized logistical and implementation needs and
considerations, clarified existing gaps, and helped with the identification of public
health and programmatic resolutions. This Special Issue was assembled and designed
to allow symposium participants to highlight these discussions, and to enable readers
to learn and think about this important topic and consider ways forward. This Editorial
provides a brief walkthrough of the Special Issue’s 10 manuscripts, each of which
stands on its own, yet they all address the theme of the aforementioned symposium
and of the supplement. The overall design of this Special Issue includes an overview
of the topic of NGS for HIV-1 drug resistance testing, lessons from the past and how
they can guide us, special considerations, preliminary actual data, and logistical
concerns towards the future.
Ji et al. [19] and Avila-Rios et al. [20] provide an overview to the theme of the
Special Issue. Ji et al. introduce the Second Winnipeg Symposium and highlight existing
technical and knowledge gaps related to the adoption of NGS for HIV-1 drug resistance
testing in clinical care, public health, and research. Avila-Rios et al. then focus
on laboratory, clinical, and implementation considerations and the need for standardization
and quality assurance of NGS-based HIV-1 drug resistance genotyping. Both papers discuss
potential sources of variation and bias in the general NGS workflow, with some focus
on resource limited settings, and present the need for the establishment of EQA programs
to address existing challenges.
The next group of manuscripts present lessons from the past and how they might impact
our way forward when considering NGS for HIV-1 drug resistance testing. Jennings et
al. [21] discuss challenges in applying experience earned from a Sanger-based EQA
strategy within the National Institute of Allergy and Infectious Diseases (NIAID)
Virology Quality Assurance (VQA) program towards NGS HIV-1 drug resistance assays,
including already started initiatives. Lee et al. [22] then present unique requirements
and challenges in conducting EQA for NGS-based HIV-1 drug resistance testing, and
consider the differences such a program might mandate as compared to the conventional
Sanger sequencing approach.
Special considerations relevant for using NGS to detect HIV-1 drug resistance mutations
are discussed in the next group of manuscripts. Zhou et al. [23] focus on the important
yet challenging accurate detection of minor drug-resistant variants in HIV-1 quasispecies,
the potential for this error-prone process to confound interpretation, and existing
ways to remove such errors. Capina et al. [24] then consider the importance of internal
laboratory complex NGS quality control processes and how they might challenge conventional
quality management operations. Finally, Noguera-Julian et al. [25] discuss ‘dry laboratory
data panels’ (rather than ‘wet laboratory sample panels’) and how they can support
EQA programs for NGS-based HIV-1 drug resistance testing. Such panels have been used
for Sanger sequencing, and are needed, considering that bioinformatic analyses remain
an important bottleneck that should be addressed, particularly with the more complex
NGS data interpretation process.
The next two manuscripts in this Special Issue present initial data from actual use
of an NGS EQA program. Becker et al. [26] discuss performance assessment criteria
for NGS-based HIV-1 drug resistance assays and propose a new validation, evaluation,
and standardization system that could be used for accreditation and quality assurance
purposes. Then Parkin et al. [27] describe a preliminary multi-laboratory comparison
of NGS to Sanger sequencing for HIV-1 drug resistance testing, with close attention
to the detection of minority drug-resistance variants.
In the final manuscript of the Special Issue, Ji et al. [28] summarize the last session
of the symposium, and discuss logistical considerations, which may inform the development
of an EQA program for NGS HIV-1 drug resistance testing.
Taken together, I hope that the contents of the Special Issue will contribute to the
continued imperative discussion on if and how NGS should be incorporated into HIV-1
drug resistance testing for clinical care, research, and public health, and the unique
role of a dedicated EQA program in this process. A ‘consensus’ to address such questions
is currently lacking, however, this conversation is valuable and essential towards
planning the next steps and establishing EQA programs to support such steps.
Finally, I would like to thank all of the authors, reviewers, editors, and Viruses
personnel who made this Special Issue possible. Special thanks go to the Organizing
Committee of the Second International Winnipeg Symposium on NGS HIV-1 Drug Resistance,
headed by Drs. Hezhao Ji and Paul Sandstrom.