Hartnup disorder (OMIM 234500) is an autosomal recessive abnormality of renal and gastrointestinal neutral amino acid transport noted for its clinical variability. We localized a gene causing Hartnup disorder to chromosome 5p15.33 and cloned a new gene, SLC6A19, in this region. SLC6A19 is a sodiumdependent and chloride-independent neutral amino acid transporter, expressed predominately in kidney and intestine, with properties of system B 0. We identified six mutations in SLC6A19 that cosegregated with disease in the predicted recessive manner, with most affected individuals being compound heterozygotes. The disease-causing mutations that we tested reduced neutral amino acid transport function in vitro. Population frequencies for the most common mutated SLC6A19 alleles are 0.007 for 517G-A and 0.001 for 718C-T. Our findings indicate that SLC6A19 is the long-sought gene that is mutated in Hartnup disorder; its identification provides the opportunity to examine the inconsistent multisystemic features of this disorder. 14 C-Amino acid uptake 14 C-Leucine uptake Figure 1 Ion and voltage dependence and substrate specificity of SLC6A19 confirm that it has the predicted profile for system B 0. (a) Leucine uptake (pmol per 15 min) in oocytes transfected with SLC6A19 cRNA in which buffer containing NaCl (Na) was modified. The transport activity of oocytes injected with water was subtracted (n ¼ 3 experiments). Expression of SLC6A19 resulted in uptake of 100 mM 14 C-leucine at 2073 pmol per 15 min, which was more than twice that detected in oocytes injected with water (net activity 871.8 pmol per 15 min). Uptake of 14 C-leucine was sodium-dependent, as replacement of sodium ions by the impermeant N-methyl-D-glucamine (NMDG) or LiCl (Li) reduced the transport activity by 92% or 85%, respectively. Leucine uptake was not chloride-dependent, as replacement of NaCl by sodium gluconate (-Cl) did not significantly alter transport activity (P40.1). Transport of amino acids by SLC6A19 was driven by membrane potential, as the addition of 50 mM KCl (+ K) to the transport buffer reduced leucine uptake by 58%. (b) Uptake (pmol per 15 min) of 14 C-labeled amino acids in oocytes transfected with SLC6A19 cRNA or controls injected with water. The specificity for neutral amino acids is shown in this experiment, which was done three times. Phenylalanine seemed to be the best substrate, followed by leucine, glutamine and alanine. Glutamate and arginine were not actively transported.

Human immunodeficiency virus (HIV) controllers are rare individuals who spontaneously control HIV type 1 replication for 10 years or more in the absence of antiretroviral treatment. In the present study, HIV controllers (n ‫؍‬ 11) maintained potent HIV-specific CD4 responses in spite of very low antigenic loads. Their CD4؉ central memory T (T CM ) cells were characterized by near-normal numbers and preserved interleukin-2 (IL-2) secretion in response to HIV antigens and uniformly high expression of the survival receptor IL-7 receptor ␣ (IL-7R␣). Controllers expressed CCR7 at higher levels than uninfected controls, suggesting differences in T CM -cell homing patterns. CD4؉ effector memory T (T EM )-cell responses were polyfunctional in HIV controllers, while IL-2 secretion was lost in viremic patients. Cytokine production was three times higher in controllers than in treated patients with undetectable viral loads, suggesting an intrinsically more efficient response in the former group. The total CD4؉ T EM -cell pool underwent immune activation in controllers, as indicated by increased HLA-DR expression, decreased IL-7R␣ expression, a bias towards gamma interferon production upon polyclonal stimulation, and increased macrophage inflammatory protein 1␤ secretion associated with chronic CCR5 down-regulation. Thus, HIV controllers showed a preserved CD4؉ T CM -cell compartment and signs of potent functional activation in the CD4؉ T EM -cell compartment. While controllers did not show the generalized immune activation pattern associated with disease progression, they had signs of immune activation restricted to the effector compartment. These findings suggest the induction of an efficient, nondetrimental type of immune activation in patients who spontaneously control HIV.

The severe acute respiratory syndrome (SARS) epidemic of 2003 was responsible for 774 deaths and caused significant economic damage worldwide. Since July 2003, a number of SARS cases have occurred in China, raising the possibility of future epidemics. We describe here a rapid, sensitive, and highly efficient assay for the detection of SARS coronavirus (SARS-CoV) in cultured material and a small number (n ‫؍‬ 7) of clinical samples. Using rolling circle amplification (RCA), we were able to achieve sensitive detection levels of SARS-CoV RNA in both solid and liquid phases. The main advantage of RCA is that it can be performed under isothermal conditions with minimal reagents and avoids the generation of false-positive results, a problem that is frequently encountered in PCR-based assays. Furthermore, the RCA technology provides a faster, more sensitive, and economical option to currently available PCR-based methods.Severe acute respiratory syndrome (SARS) is an emerging disease caused by the novel SARS coronavirus (SARS-CoV) (2,4,5,14). By the end of the SARS epidemic in July 2003, a total of 8,096 SARS cases had been reported from 30 countries, with 774 deaths. Whether future outbreaks of SARS will occur is unknown at present. However, given the recent SARS cases in southern China arising from an unknown source and a number of laboratory-related infections (12), it is important to be prepared for such a possibility. In the absence of a SARSCoV vaccine or antiviral drugs, the use of strict infection control policies and early diagnosis with rapid, sensitive, and highly specific laboratory methods are essential for the early management of SARS-CoV infection.Apart from epidemiological linkages, the clinical and radiographic features of the disease are not SARS specific, identifying a need for specific laboratory tests that can confirm SARS-CoV infection early in the course of the illness. Detection of SARS-CoV-specific antibodies is a sensitive and specific but is not possible at clinical presentation (6,14).Detection of SARS-CoV by reverse transcription-PCR (RT-PCR) in clinical specimens allows diagnosis in the early stage of the disease. However, in contrast to many other acute respiratory infections, only low levels of SARS-CoV are thought to be present during the early symptomatic phase of infection. On the basis of the results of first-generation RT-PCR assays, SARS-CoV RNA can be detected with a sensitivity of only ca. 30 to 50% in a single respiratory specimen. A higher sensitivity can be achieved if serial samples are collected, particularly during the second week of illness when maximal virus shedding occurs (13,14). The type of clinical sample (e.g., nasopharyngeal aspirate, throat swabs, stool samples, urine, etc.) also affects the sensitivity of .Recently, the utility of circularizable oligonucleotides, or "padlock probes," has been demonstrated for the detection of target nucleic acid sequences; this approach shows greater sensitivity than conventional PCR (3,8,16). Upon hybridization to a target DNA or...