CD56 Expression Marks Human Group 2 Innate Lymphoid Cell Divergence from a Shared NK Cell and Group 3 Innate Lymphoid Cell Developmental Pathway.

According to the established model of murine innate lymphoid cell (ILC) development, helper ILCs develop separately from natural killer (NK) cells. However, it is unclear how helper ILCs and NK cells develop in humans. Here we elucidated key steps of NK cell, ILC2, and ILC3 development within human tonsils using ex vivo molecular and functional profiling and lineage differentiation assays. We demonstrated that while tonsillar NK cells, ILC2s, and ILC3s originated from a common CD34-CD117+ ILC precursor pool, final steps of ILC2 development deviated independently and became mutually exclusive from those of NK cells and ILC3s, whose developmental pathways overlapped. Moreover, we identified a CD34-CD117+ ILC precursor population that expressed CD56 and gave rise to NK cells and ILC3s but not to ILC2s. These data support a model of human ILC development distinct from the mouse, whereby human NK cells and ILC3s share a common developmental pathway separate from ILC2s.

Quantifying integrated SIV-DNA by repetitive-sampling Alu-gag PCR.

OBJECTIVES: Although antiretroviral therapy (ART) effectively suppresses HIV-1 replication, it does not eradicate the virus and ART interruption consistently results in rebound of viraemia, demonstrating the persistence of a long-lived viral reservoir. Several approaches aimed at reducing virus persistence are being developed, and accurate measurements of the latent reservoir (LR) are necessary to assess the effectiveness of anti-latency interventions. We sought to measure the LR in SIV/SHIV-infected rhesus macaques (RMs) by quantifying integrated SIV-DNA. METHODS: We optimised a repetitive sampling Alu-gag PCR to quantify integrated SIV-DNA ex vivo in ART-naïve and ART-experienced SIV/SHIV-infected RMs. RESULTS: In ART-naïve RMs, we found the median level of integrated SIV-DNA to be 1660 copies and 866 copies per million PBMC during untreated acute and chronic SHIV infection, respectively. Integrated and total SIV-DNA levels were positively correlated with one another. In ART-treated RMs, integrated SIV-DNA was readily detected in lymph nodes and spleen and levels of total (3319 copies/million cells) and integrated (3160 copies/million cells) SIV-DNA were similar after a median of 404 days of ART. In peripheral blood CD4+ T cells from ART-treated RMs, levels of total (3319 copies/million cells) and integrated (2742 copies/million cells) SIV-DNA were not significantly different and were positively correlated. CONCLUSIONS: The assay described here is validated and can be used in interventional studies testing HIV/SIV cure strategies in RMs. Measurement of integrated SIV-DNA in ART-treated RMs, along with other reservoir analyses, gives an estimate of the size of the LR.

Transmission of chronic wasting disease identifies a prion strain causing cachexia and heart infection in hamsters.

Chronic wasting disease (CWD) is an emerging prion disease of free-ranging and captive cervids in North America. In this study we established a rodent model for CWD in Syrian golden hamsters that resemble key features of the disease in cervids including cachexia and infection of cardiac muscle. Following one to three serial passages of CWD from white-tailed deer into transgenic mice expressing the hamster prion protein gene, CWD was subsequently passaged into Syrian golden hamsters. In one passage line there were preclinical changes in locomotor activity and a loss of body mass prior to onset of subtle neurological symptoms around 340 days. The clinical symptoms included a prominent wasting disease, similar to cachexia, with a prolonged duration. Other features of CWD in hamsters that were similar to cervid CWD included the brain distribution of the disease-specific isoform of the prion protein, PrP(Sc), prion infection of the central and peripheral neuroendocrine system, and PrP(Sc) deposition in cardiac muscle. There was also prominent PrP(Sc) deposition in the nasal mucosa on the edge of the olfactory sensory epithelium with the lumen of the nasal airway that could have implications for CWD shedding into nasal secretions and disease transmission. Since the mechanism of wasting disease in prion diseases is unknown this hamster CWD model could provide a means to investigate the physiological basis of cachexia, which we propose is due to a prion-induced endocrinopathy. This prion disease phenotype has not been described in hamsters and we designate it as the 'wasting' or WST strain of hamster CWD.