Monitoring of anti-SARS-CoV-2 IgG antibody immune response in infected and immunised healthcare workers in Hungary: a real-world longitudinal cohort study

IntroductionSARS-CoV-2 infections have very different clinical manifestations and anti-SARS-CoV-2 immunisation may also trigger very different levels and length of protection. While (re)infection after previous COVID-19 illness or following vaccination are known, their impact and the optimal timing of any booster vaccination is currently debated. International evidence about potential underlying immune response differences remains limited and is currently not available in Hungary. MethodsWe prospectively investigated the magnitude of immune responses to infection or immunisation, their over-time changes and the occurrence of new infections through anti-SARS-CoV-2 IgG levels and the association with selected individual and clinical parameters in two voluntary cohorts of healthcare workers at a public teaching hospital in a real-world longitudinal cohort study in Hungary. In the first cohort, the anti-nucleocapsid IgG levels of 42 health care workers (female: 100%) with SARS-CoV-2 infection were followed-up over 8 months between June 2020 and February 2021. Beyond the change in immune response, associations with age, selected existing chronic conditions, blood type and severity of symptoms were investigated. In the immunised cohort, anti-spike-RBD protein IgG levels of 49 health care workers (female: 73%) with no prior COVID-19 infection were monitored up to 4 months following initial immunisation with BNT162b2 vaccine between December 2020 and April 2021. Statistical analyses included median analysis, linear regression, ANCOVA, Kruskal-Wallis test and Skillings-Mack test for block designs as relevant. ResultsWithin the infected cohort, the median time of anti-SARS-CoV-2 IgG level reduction below the positive test cut-off was 6 months. First month IgG levels were on average the highest among those in illness severity category 4, but the difference to less severe categories was not statistically significant. Higher age was associated with higher IgG levels. Within the immunised cohort, the anti-SARS-CoV-2 spike-RBD protein IgG levels increased 25-fold between the first and second immunisations, significantly decreased to 33% of the peak level after 90 days, and had an overall negative tendency with older age and male sex. IgG monitoring revealed 17% (7/42) and 14% (7/49) new infections in the infected and the immunised cohorts, respectively, all symptomless. DiscussionOur study is the first to investigate the level, change and associations of anti-SARS-CoV-2 IgG immune response in infected or immunised healthcare workers in Hungary. It provides further evidence about the significantly declining IgG protection through initial infection beyond 6 months. While immunisation with mRNA vaccination shows a similar pattern of reduction in protection, IgG levels remained within the positive range at 4 months. The observed rate of 15% new, asymptomatic infections and their potential broader impacts call for further investigations. Overall, our findings are confirmative of the effectiveness of vaccination to prevent illness, recent considerations for booster vaccination beyond 6 months, and indicate the potential benefit of anti-SARS-CoV-2 IgG monitoring for optimisation.

Characterization of an integrated, endogenous mouse mammary tumor virus-like (MMTV) betaretrovirus genome in a black Syrian hamster (Mesocricetus auratus).

Retroviruses (family Retroviridae) are important agents of humans and animals. This study reports the detection and complete genome characterization of a novel endogenous retrovirus from the black Syrian hamster (Mesocricetus auratus) with a squamous cell skin tumor. The proviral genome, tentatively named black Syrian hamster retrovirus (BSHRV/2013/HUN, MK304634), was 8784 nucleotide in length with typical full-length betaretrovirus genome organization of 5'LTR-gag-pro-pol-env-3'LTR and with a characteristic mouse mammary tumor virus-like (MMTV) betaretrovirus dUTPase domain but without a sag gene. The BSHRV gag (534aa), pro/pol (~1099aa) and env (672aa) proteins had 56%/63%/50% aa identity to the corresponding proteins of MMTV (AF228552). The proviral DNA is detectable in tumor as well as in tumor-free cells by conventional PCR and qPCR but only visible in the tumor cells by in situ hybridization. Low level retroviral RNA expression was found only in the DNase-treated RNA tumor samples using RT/nested PCR. BSHRV/2013/HUN-like betaretrovirus DNA was also identified from a faecal and tissue samples from 1 of the further 3 tested individuals by nested-PCR and qPCR. Further research is needed to investigate the distribution, activity and etiological role of this novel MMTV-like betaretrovirus species in hamster.

Design, synthesis, and in vitro activity of novel drug delivery systems containing tuftsin derivatives and methotrexate.

During the past decade, biodegradable polymers or oligopeptides recognized by cell-surface receptors have been shown to increase drug specificity, lowering systemic drug toxicity in contrast to small-size fast-acting drugs. The goal of the present study was to develop anticancer bioconjugates based on chemotactic drug targeting (CDT). These constructs are composed of methotrexate (Mtx) attached to a tuftsin-like peptide carrier through an enzyme-labile pentapeptide spacer (GFLGC) and several copies of a chemotactic targeting moiety (H-TKPR, For-TKPR, H-TKPKG, and Ac-TKPKG). Carriers with targeting moieties in the branches were prepared by solid-phase synthesis using mixed Boc and Fmoc strategies. The drug molecule connected to an enzyme-labile spacer was attached to the branched oligopeptide in solution. In vitro chemotaxis, cellular uptake, and cytotoxicity assays were carried out on the MonoMac6 cell line. The most effective conjugates with H-TKPR or Ac-TKPKG targeting moieties in the branches, which have the most advantageous chemotactic properties, can be internalized rapidly, and these conjugates trigger higher toxic effect than the free drug (Mtx). The results suggest that our tuftsin-based drug delivery systems might be potential candidates for targeting cancer chemotherapy.

Synthesis of oligotuftsin-based branched oligopeptide conjugates for chemotactic drug targeting.

The synthesis and chemotactic properties of a new class of branched oligopeptide-based conjugates are described. Tetratuftsin derivatives containing chemotactic formyl tripeptides (For-MLF, For-NleLF or For-MMM) in branches were prepared by stepwise solid-phase peptide synthesis. The influence of the composition and ionic charge of the carrier-branched oligopeptide on the chemotactic behaviour of the conjugate was studied in Tetrahymena pyriformis. Conjugates with methotrexate (Mtx) as a drug component was also prepared. For this, a GFLGC spacer, cleavable by cathepsin B, was used. The spacer with N-terminal methotrexate was coupled to the chloroacetylated chemotactic carrier molecule by thioether bond formation. The chemotactic activity and cytotoxity of Mtx conjugates were also studied.

Association of angiotensin II type 1 receptor polymorphism with resistant essential hypertension.

Angiotensin II type 1 receptor (AT1) mediates the vasoconstrictive and growth-promoting effect of angiotensin II in humans. It has been reported that a polymorphism of the AT1 gene (an A/C transversion at position 1166: A-C1166) occurs more frequently in resistant hypertensives taking two or more antihypertensive drugs. On the contrary, a recent study of the influence of the A-C1166 polymorphism on aortic stiffness demonstrated that the distribution of the genotypes did not differ between normotensive and hypertensive subjects. In addition, a recent population-based survey of Caucasian hypertensives reported lower blood pressure values in CC homozygotes than in heterozygotes and AA homozygotes. Because of these controversial results and the lack of a sufficient amount of data the present study was designed to assess the contribution of the AT, gene A-C1166 polymorphism to resistant essential hypertension. Forty-eight subjects with resistant essential hypertension (HT) and 48 normotensive (NT), age and sex-adjusted controls (from a population of 300 healthy blood donors) were selected. All subjects were genotyped for the A-C1166 polymorphism in the 3'-UTR of the AT1 gene using PCR-based techniques. The influence of genotype on blood pressure (BP) was investigated using ANOVA Randomized Complete Block (ANOVA RCB) design according to sex, age and BMI. There were no significant differences in allele or genotype frequencies between HT and NT subjects (X2 = 0.61; P = NS). In HT subjects higher values of systolic blood pressure were associated with the C allele of the AT1 gene only in older and overweight patients (P < 0.001 and P < 0.001, respectively). Also in HT patients an association between the presence of the C allele of the AT1 gene and higher values of diastolic blood pressure was present in overweight patients (P = 0.001). These results suggest that in resistant hypertensive subjects the AT1 A-C1166 polymorphism is potentially involved in the regulation of blood pressure. As the effects of genotypes on blood pressure are pronounced in older and overweight subjects this polymorphism may amplify the effects of age and BMI on resistant essential hypertension.