We investigated the persistence of SARS-CoV-2-specific neutralizing antibodies in serum (CoV-2-SNAb) against the "WH-Human 1" coronavirus in 57 convalescent persons from January 2020 to January 2021. The CoV-2-SNAb response against authentic "WH-Human 1" showed a significant (p < 0.01) neutralizing high effect (≥95%) in the following manner: by 94.7% neutralization for up to 6 months, by 73.1% for up to 8 months, and by 31.7% for up to 10 months in correlation with a significant decrease in the concentration of the virus determined by SARS-CoV-2 spike protein extracellular domain and spike-receptor-binding domain (S-RBD). There was neutralizing effect (<95%) when the S-RBD optical density (OD) value was more than 1.0, showing a suitable threshold of S-RBD = 1.0 (antibody-tittering, OD). However, in some convalescent persons, no neutralizing effect (<95%) was observed although the SARS-CoV-2-specific neutralizing antibodies were bound to the S-RBD (OD >1.0). The neutralization of the virus in these cases may not involve S-RBD, but rather B- and T cell memory responses in overall immunity, using the threshold value (OD = 1.0) of S-RBD as a simple and effective method to determine the neutralization effect of the antibody efficacy and use of vaccination in combination with a standard pseudovirus neutralizing assay. We suggest that convalescent persons should contact their physicians 6-month postinfection to test the function of their serum neutralizing antibodies and determine whether administering a SARS-CoV-2 vaccine is necessary to prevent the development of severe illness in the future.

Early discover of risk progression of invisible carcinomas is important for a prerequisite successful treatment. Here, we investigated whether concentration of human thymidine kinase 1 (HTK1) discover invisible malignant human tumours. The HTK1 concentration of tumour cellular based on HTK1 IgY-polyclonal-antibody (HTK1-IgY-pAb) was determined by using a novel automatic chemiluminescence analyser with sandwich biotin-streptavidin (SBSA) platform. Minimum number of cells able to be detected by this technology used cells with low and high concentration of HTK1. The limit visibility by tumour imaging is approximately 1 mm in diameter, corresponding to approximately 10⁹ cells with a cell diameter of 1 µm. Based on a HTK1 standard curve and a molecular weight of HTK1 of 96 kD, the HTK1protein (HTK1p) concentration per cell was calculated to be 0.021 pg. Assuming 200 pg in total protein/cell, approximately 50 × 10⁶ growing malignant cells in the body were calculated to releases HTK1 into 5-liter blood. A HTK1 values of 3.914, 0.435 and 0.009 pmol/L corresponds to 10 × 10⁵, 2 × 10⁵ and 1 × 10⁵ growing malignant cells, respectively. The lowest detectable sensitivity of HTK1 is 0.009 pmol/L in 1 × 10⁵ growing malignant cells and 0.01 pmol/L in blood serum, detectable in health screening. Comparing the novel automatic chemiluminescence analyser with the original ECL dot-blot assay using serum HTK1p (health screening, n = 265) showed high correlation (r = 0.8743, P < .000). In conclusion, the novel automatic chemiluminescence analyser with SBSA platform is a reliable method with high accuracy to determine carcinoma invisible.

To assess whether serum thymidine kinase 1 (STK1p), CEA and CA19.9 can be used as prognostic biomarkers in the primary tumor location (PTL) of colorectal carcinoma (CRC). Additional clinical factors of TNM stage, pathological grade, age and sex were also included.

STK1p was determined by an ECL-dot-blot assay, and CEA/CA19.9 was determined by an automatic electrochemiluminescence analyzer in a retrospective presurgery of right-colon carcinoma (R-CC, n = 90), left-colon carcinoma (L-CC, n = 128) and rectal carcinoma (RC, n = 270). Prognostic factors were evaluated by COX and overall survival (OS).

The multivariate-COX and OS in relation to the prognostic factors of PTL in CRC were different and complex. An elevated STK1p value was significantly associated with poor OS in RC (P = 0.002) and L-CC (P = 0.037) but not in R-CC (P > 0.05). Elevated CEA (P≈.000) and CA19.9 (P≈.000) were significantly associated with poor OS in RC but not in L-CC and R-CC. Multivariate-COX showed that STK1p (P = 0.02, HR = 1.779, 95%CI 1.30–7.582), CEA (P = 0.001, HR = 2.052, 95%CI 1.320–3.189), CA19.9 (P≈.000, HR = 2.574, 95%CI 1.592–4.162) and TNM-stage (P≈.000, HR = 2.368, 95%CI 1.518–3.694) were independent prognostic factors in RC, while TNM-stage was an independent prognostic factor only in R-CC (P = 0.011, HR = 3.139, 95% CI 1.30–7.582) and L-CC (P≈.000, HR = 4.168, 95%CI 1.980–8.852). Moreover, elevated STK1p was significantly more sensitive (P < .001) for predicting mortality than CEA and CA19.9. No correlation was found between STK1p, CEA or AFP.

Combining TNM stage and suitable biomarkers, STK1p provides further reliable information on the survival of PTL of CRC.