Establishment of a peptide-based enzyme-linked immunosorbent assay for detecting antibodies against PRRSV M protein.

BACKGROUND: Porcine reproductive and respiratory syndrome (PRRS) is one of the most economically devastating diseases affecting the swine industry globally. Evaluation of antibody responses and neutralizing antibody titers is the most effective method for vaccine evaluation. In this study, the B cell line epitopes of PRRSV M protein were predicted, and two peptide ELISA assays were established (M-A110-129 ELISA, M-A148-174 ELISA) to detect antibodies against PRRSV M protein. Field serum samples collected from pig farms were used to validate the peptide ELISA and compare it with an indirect immunofluorescence assay. RESULTS: The sensitivity and specificity of M-A110-129 ELISA and M-A148-174 ELISA were (111/125) 88.80%, (69/70) 98.57% and (122/125) 97.60%, (70/70) 100%, relative to indirect immunofluorescence assay. This peptide ELISA could detect antibodies against different genotypes of PRRSV including type 1 PRRSV, classical PRRSV, HP-PRRSV, and NADC30 like PRRSV, but not antibodies against other common swine viruses. The results of ROC analysis showed that the area under the curve (AUC) of the M-A110-129 ELISA and M-A148-174 ELISA were 0.967 and 0.996, respectively. Compared the concordance of results using two peptide ELISA assays, the IDEXX PRRSV X3 Ab ELISA and a virus neutralization test, were assessed using a series of 147 sera from pigs vaccinated with the NADC30-like PRRSV inactivated vaccine. The M-A148-174 ELISA had the best consistency, with a Cohen's kappa coefficient of 0.8772. The concordance rates of the Hipra PRRSV ELISA kit, M-A110-129 ELISA and M-A148-174 ELISA in the field seropositive detection results were 91.08, 86.32 and 95.35%, relative to indirect immunofluorescence assay. CONCLUSIONS: In summary, compared with M-A110-129 ELISA, the PRRSV M-A148-174 ELISA is of value for detecting antibodies against PRRSV and the evaluation of the NADC30-like PRRSV inactivated vaccine, but the advantage is insufficient in serological early diagnosis.

A Retrospective Study from 2 Centers in China on the Effects of Continued Use of Angiotensin-Converting Enzyme Inhibitors and Angiotensin II Receptor Blockers in Patients with Hypertension and COVID-19.

BACKGROUND Use of renin-angiotensin-aldosterone system inhibitors in coronavirus disease 2019 (COVID-19) patients lacks evidence and is still controversial. This study was designed to investigate effects of angiotensin-converting enzyme inhibitors (ACEIs) or angiotensin II receptor blockers (ARBs) on clinical outcomes of COVID-19 patients and to assess the safety of ACEIs/ARBs medication. MATERIAL AND METHODS COVID-19 patients with hypertension from 2 hospitals in Wuhan, China, from 17 Feb to 18 Mar 2020 were retrospectively screened and grouped according to in-hospital medication. We performed 1: 1 propensity score matching (PSM) analysis to adjust for confounding factors. RESULTS We included 210 patients and allocated them to ACEIs/ARBs (n=81; 46.91% males) or non-ACEIs/ARBs (n=129; 48.06% males) groups. The median age was 68 [interquartile range (IQR) 61.5-76] and 66 (IQR 59-72.5) years, respectively. General comparison showed mortality in the ACEIs/ARBs group was higher (8.64% vs. 3.88%) but the difference was not significant (P=0.148). ACEIs/ARBs was associated with significantly more cases 7-categorical ordinal scale >2 at discharge, more cases requiring Intensive Care Unit (ICU) stay, and increased values and ratio of days that blood pressure (BP) was above normal range (P<0.05). PSM analysis showed no significant difference in mortality, cumulative survival rate, or other clinical outcomes such as length of in-hospital/ICU stay, BP fluctuations, or ratio of adverse events between groups after adjustment for confounding parameters on admission. CONCLUSIONS We found no association between ACEIs/ARBs and clinical outcomes or adverse events, thus indicating no evidence for discontinuing use of ACEIs/ARBs in the COVID-19 pandemic.

[Therapeutic effects of different doses of methylprednisolone on smoke inhalation-induced acute lung injury in rats].

OBJECTIVE: To investigate the therapeutic effect of different doses of methylprednisolone (MP) in smoke inhalation-induced acute lung injury (SI-ALI). METHODS: Adult male Sprague-Dawley (SD) rats were divided into control group (group A, n = 6), smoke inhalation group (group B, smoke inhalation 30 minutes, n = 30) and smoke + MP 40, 4, 0.4 mg/kg intervention group (groups C, D, E; intraperitoneal injection of MP at 1 hour before smoke inhalation, n = 30) according to random number table method. The survival status of rats in each group was observed at 24 hours, and murine smoke inhalation induced trauma score (MSITS) according to the symptoms and signs of rats at 3 hours after smoke inhalation were scored. The blood of abdominal aorta of rats was collected. Then the rats were sacrificed to harvest bronchoalveolar lavage fluid (BALF) and lung tissue. The levels of interleukin (IL-6, IL-17a) in plasma and BALF were detected by enzyme linked immunosorbent assay (ELISA); the total number of white blood cells and the proportion of leukocytes or macrophages in BALF were calculated; the histopathological changes of lung were observed and the lung injury score was given; the expression of myeloperoxidase (MPO) and high mobility group protein B1 (HMGB1) in lung tissue were detected by Western Blot. RESULTS: The 24-hour survival rate of group B rats was 33.67%. The survival rate of groups C, D and E (65.73%, 85.17%, 60.07%) were significantly higher than that of group B (all P < 0.05), and the survival rate of group D was significantly higher than that of groups C and E. Diffuse inflammatory cell infiltration, intra-alveolar hemorrhage and a large amount of edema fluid were seen in the lung tissue of group B; and the lung injury score was significantly higher than that of group A. Compared with group B, the lung injury in different doses of MP group were decreased to different degrees, while the lung injury scores in groups C and D were significantly decreased (3.31±1.37, 2.62±0.98 vs. 5.52±0.97, both P < 0.01); correlation analysis showed that MSITS score was significantly and positively correlated with lung injury score (r = 0.862, P < 0.001). The levels of plasma inflammatory factors and BALF protein, inflammatory cells and inflammatory factors, and the expression of MPO, HMGB1 in group B were significantly higher than those in group A. Compared with group B, the levels of inflammatory factors in plasma, and protein content, inflammatory cells and inflammatory factors in BALF in different doses of MP group were decreased to different degrees, with significant differences in groups C and D [plasma: IL-17a (pg/L): 49.28±27.12, 36.57±16.52 vs. 191.79±88.21; IL-6 (ng/L): 206.47±109.96, 197.52±113.86 vs. 669.00±299.60; BALF: protein content (mg/L): 892.0±164.5, 566.1±120.9 vs. 1 838.0±145.8; white blood cell count (×109/L): 5.40±1.67, 2.81±1.20 vs. 9.02±2.06; neutrophil ratio: 0.315±0.081, 0.273±0.080 vs. 0.590±0.096; IL-17a (ng/L): 22.63±8.62, 18.92±8.43 vs. 43.31±19.17; IL-6 (ng/L): 156.49±46.94, 123.66±64.91 vs. 253.43±80.03; all P < 0.01]; in addition, the expression of MPO and HMGB1 protein in lung tissues of MP groups with different doses were significantly decreased, the expression of MPO in group D was significantly lower than that in group E [MPO/ß-actin (fold increase from group A): 2.14±0.97 vs. 4.35±0.87, P < 0.01], the expression of HMGB1 in groups C and D were significantly lower than that in group E [HMGB1/ß-actin (fold increase from group A): 1.77±0.73, 1.23±0.67 vs. 3.65±1.08, both P < 0.05]. CONCLUSIONS: MP can significantly improve the survival rate of SI-ALI rats and reduce the acute pulmonary and systemic inflammatory response. The MP effect of 4 mg/kg was better than 40 mg/kg and 0.4 mg/kg.