The coronavirus disease 2019 ) pandemic now has >2,000,000 confirmed cases worldwide. COVID-19 is currently diagnosed using quantitative RT-PCR methods, but the capacity of quantitative RT-PCR methods is limited by their requirement of high-level facilities and instruments. We developed and evaluated reverse transcription loop-mediated isothermal amplification (RT-LAMP) assays to detect genomic RNA of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative virus of COVID-19. RT-LAMP assays reported in this study can detect as low as 100 copies of SARS-CoV-2 RNA. Cross-reactivity of RT-LAMP assays to other human coronaviruses was not observed. A colorimetric detection method was adapted for this RT-LAMP assay to enable higher throughput.

Coronavirus disease 2019 (COVID-19) is newly emerging human infectious diseases, which is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2, also previously known as 2019-nCoV). Within two months of the outbreak, more than 80,000 cases of COVID-19 have been confirmed worldwide. Since the human to human transmission occurred easily and the human infection is rapidly increasing, the sensitive and early diagnosis is essential to prevent the global outbreak. Recently, World Health Organization (WHO) announced various primer and probe sets for SARS-CoV-2 previously developed in China, Germany, Hong Kong, Japan, Thailand, and USA. In this study, we compared the ability to detect SARS-CoV-2 RNA among the seven primer-probe sets for N gene and the three primer-probe sets for Orf1 gene. The result of the comparative analysis represented that the ‘2019-nCoV_N2, N3’ of USA and the ‘ORF1ab’ of China are the most sensitive primer-probe sets for N and Orf1 genes, respectively. Therefore, the appropriate combination from ORF1ab (China), 2019-nCoV_N2, N3 (USA), and NIID_2019-nCOV_N (Japan) sets should be selected for the sensitive and reliable laboratory confirmation of SARS-CoV-2.

Since the earliest days of the HIV epidemic, the number of CD4 ؉ T cells per unit volume of blood has been recognized as a major prognostic factor for the development of AIDS in persons with HIV infection. It has also been generally accepted that approximately 2% of total body lymphocytes circulate in the blood. In the present study, we have used a nondepleting humanized anti-CD4 monoclonal antibody labeled with the gamma emitter indium-111 to visualize the CD4 ؉ T-cell pool in vivo in nonhuman primates with simian HIV infection. A strong correlation was noted between radiotracer uptake in spleen, tonsil, axillary lymph nodes, and peripheral blood CD4 T-cell counts ( ‫؍‬ 0.75, 0.93, and 0.85, respectively, P < .005). The relationship between radiotracer retention in lymphoid tissues and CD4 ؉ T-cell counts in the circulation was governed by an exponential law. These data provide an estimate for the total number of lymphocytes in the body as being between 1.9 and 2.9 ؋ 10 12 and suggest that the partition between peripheral blood and lymphoid tissue is between 0.3% and 0.5%. (Blood. 2009; 114:328-337)