A review of HLA and COVID-19 association studies

Coronavirus disease 2019 (COVID-19), caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is reported to vary across different populations in the prevalence of infection, in the death rate of patients, in the severity of symptoms and in the drug response of patients. Among host genetic factors that can influence all these attributes human leukocyte antigen (HLA) genetic system stands out as one of the leading candidates. Case-control studies, large-scale population-based studies, as well as experimental bioinformatics studies are of utmost importance to confirm HLA susceptibility spectrum of COVID-19. This review presents the results of the first case-control and epidemiological studies performed in several populations, early after the pandemic breakout. The results are pointing to several susceptible and protective HLA alleles and haplotypes associations with COVID-19, some of which might be of interest for the future studies in Croatia, due to its common presence in the population. However, further multiple investigations from around the world, as numerous as possible, are needed to confirm or deteriorate these preliminary results.

miR-7 AND miR-34a sequence cloning and expression in a1235 glioblastoma cell line

miRNAs are small non-coding RNAs which have an important role in signalling circuits regulating different cell processes. miR-7 and miR-34a are known as tumour suppressors, and both of them can interfere with cell proliferation, differentiation, apoptosis and migration. We constructed plasmids containing pri-miRNA sequences for these two miRNAs and introduced them into the A1235 glioblastoma cell line. Clones containing increased expression of processed miR-7 and miR-34a were obtained. The proliferation and sensitivity to alkylation agent of transfected cells were similar to those of control cells. Our results indicate that an increase in miR-7 and miR34 expression alone in A1235 glioblastoma cells is not sufficient to change their proliferation or sensitivity to the influence of alkylating agents.

A new case of intragenic deletion of the TCF4 gene without features of Pitt-Hopkins syndrome

Different genomic alterations affecting the TCF4 gene are usually associated with Pitt-Hopkins syndrome (PTHS). This syndrome is a rare neurodevelopmental genetic disorder characterized by distinctive facial features, abnormal breathing, psychomotor delay and severe intellectual disability (ID). The genomic alterations include whole or partial gene deletion; balanced translocation disrupting the coding sequence of the gene; and intragenic variants. The TCF4 gene encodes a basic helix-loop-helix (bHLH) transcription factor 4. Using alternative promoters, TCF4 can be transcribed from a number of alternative initial exons, allowing for translation of variable protein isoforms containing different functional domains. Full-length TCF4 has two activation domains (AD1 and AD2) that are thought to modulate transcriptional activity, a NLS domain (nuclear localization signal) that controls subcellular localization and bHLH domain. Typical PTHS patients have aberration localized between exons 9 and 18 of the gene. On the other hand, variants affecting the first protein coding exons give rise to mild non-syndromic ID. We present a ten-year-old girl with psychomotor delay and mild ID without the typical features of PTHS. Genetic investigation using array-based comparative genomic hybridization, revealed a 73.45 kb deletion within the TCF4 gene. The deletion encompassing only exon 6 (NM_001083962). This deletion was not detected in both parents. Cytogenetic analysis excluded balanced translocation disrupting the coding sequence of the gene. To the best of our knowledge, this is the first case described in literature involving only exon 6. The findings in our patients support the notion that position of the alteration in TCF4 is relevant to the phenotype. Reporting our case we want to contribute to the phenotype-genotype correlation in patients with intragenomic deletion of TCF4 gene.

Routine procedures and preventive measures in tissue banking and cell therapy during COVID-19 pandemic

Following the rapid spread of SARS-CoV-2 worldwide, this article describes routine procedures and preventive measures for tissue banking and cell therapy in University Hospital Centre “Sestre milosrdnice” in the Republic of Croatia. This paper describes our current practice for preventing contamination and microbiological environmental monitoring of cleanrooms, the protection of healthcare personnel as well as patients from SARS-CoV-2. These measures are based on the recommendations obtained from the Ministry of Health of the Republic of Croatia, the Croatian Institute of Public Health and the European Centre for Disease Prevention and Control. We also present data on samples collected and treated in this period in comparison to normal work conditions before COVID-19.

Biological features of SARS-CoV-2 and current approaches to antiviral therapy and vaccination

Since the first description of patients with pneumonia of unknown origin in Wuhan in December 2019, unprecedented efforts of the international scientific community led to the identification and molecular characterization of its etiological agent, e.g. SARS-CoV-2. The global pandemic of COVID-19 represents an outstanding challenge for the scientists and medical professionals worldwide. In this review, we discuss the most important aspects of SARS-CoV-2 biology and virology including antiviral and immunomodulatory treatment strategies as well as vaccine development.

Covid-19 and the environment – the role of the Public Health Institute

The Croatian National Health Care Act defines the areas of activities of the public health institute, including the activities of the epidemiology of infectious diseases and chronic non-communicable diseases, public health, health promotion, environmental health, microbiology, school and adolescent medicine, mental health and addiction prevention at Zagreb City level. This paper reviews the highly variable activities in the Andrija Štampar Teaching Institute of Public Health with the aim of promoting a comprehensive approach to the COVID-19 pandemic. Human and analytical resources in the Institute, activities and rapid implementation of innovations testify to the high capacities for adaptation to emerging risks. In the Institute, it is possible to carry out a whole range of tests and to monitor the environmental factors with predominant impact on human health and safety of the Zagreb environment. The supply of safe water for human consumption in the Republic of Croatia during the current COVID-19 crisis has been uninterrupted and in accordance with applicable legislation. Also, our laboratories have been developing and introducing a method for wastewater testing for SARS-CoV-2 presence. The sludge from wastewater treatment plants is used in agriculture, and potential risks associated with the COVID-19 outbreak should be assessed prior to each application on the soil. Increased use of disinfectants during the epidemic may present a higher risk to the aquatic environment. Air quality monitoring indicates a positive impact on air quality as result of isolation measures.

Comparison of three methods for detection of anti-SARS-CoV-2 antibodies

A novel positive-sense RNA virus named Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) was identified in December 2019 in China. It is a systemic disease that includes severe respiratory distress, coronavirus disease 19 (Covid-19). The primary way of transmitting this virus is person-to-person contact via respiratory droplets, but it can also be transmitted by contaminated surfaces. Symptoms range from mild to severe, and the virus spreads quickly. On 11 March 2020 Covid-19 was declared a pandemic by the World Health Organization. The standard way to identify the presence of the virus is to detect its genome using real-time reverse transcriptase polymerase chain reaction (RT-PCR). It can be applied to respiratory tract samples such as nasopharyngeal swabs, sputum and bronchoalveolar lavage. In order to identify contact with the virus and immunological response of the individual, tests based on immunoassays were developed. Many of those tests were produced in short periods of time and they mostly differ on the sample that can be used (serum, plasma or whole blood), complexity and/or expense, and the class of the antibody they detect. The reliability of such tests is of high importance for epidemiological surveys as well as for the development of a vaccine. The aim of this study was to compare three commercially available immunoassay tests. Our results show that different serological tests have different sensitivity and specificity, and that the rapid option, which is the easiest to perform and has the lowest cost, provides the least reliable results.

Cytogenomics of murine melanoma cell lines C57/B1 and B16-F0

In melanoma, one of the most aggressive human tumors, early diagnosis is still the best strategy to increase survival rates. C57/B1 and B16-F0 are murine cell lines frequently applied in basic and applied melanoma research. Thus, it is striking, that cytogenomic features of these two cell lines are not known yet. In the present study, molecular cytogenetics and array-comparative genomic hybridization were done in C57/B1 and B16-F0 cells and the resulting imbalances and breakpoints were translated into the human genome. Both cell lines derived from each other and had an isochromosome 12 and a balanced translocation of chromosomes 3 and 13 in common. Interestingly, both cell lines presented aberrations which were also observed in human skin but not in human eye or uveal melanoma.

The role of HLA typing in rheumatic diseases

Association between HLA-DR4 and rheumatoid arthritis (RA) has been known for 4 decades, and amino acid sites within HLA-DRB1 (11/13, 71, 74) are highly associated with RA. HLA is not useful for diagnosis or prognosis, but it may help predict severe and erosive disease. Since 90% of patients with ankylosing spondylitis (AS) and 50-70% of other spondyloarthritis (SpA) patients are HLA-B*27 positive, HLA is a stronghold of diagnostic algorithms. Genetic predisposition to juvenile idiopathic arthritis (JIA) is mainly due to HLA class II, and to a lesser extent to HLA class I. Although HLA plays a role in rheumatic disorders, its clinical relevance is not homogeneous. When classical biomarkers are lacking or in complex cases, HLA typing may provide support for the management of patients.

Distribution of minor histocompatibility antigens HA-1, HA-2 and HA-8 in the Croatian population

Minor histocompatibility antigens (mHAgs) are polymorphic, endogenously synthetized products recognized by alloreactive T cells in the context of major histocompatibility complex molecules. Recipients of allogeneic bone marrow grafts run the risk of graft-versus-host disease (GvHD), even when the donor is an HLA-identical sibling. This may be caused by disparities in mHAgs between the donor and the recipient, with the antigen present in the recipient and not in the donor. In such cases, T cells in the transplanted donor marrow respond to the recipient’s mHAgs. We determined the allele, genotype and phenotype frequencies for mHAgs HA-1, HA-2 and HA-8 in 102 healthy, unrelated individuals previously typed for HLA-A, HLA-B and HLA-DR. We compared the results with existing studies in other populations and found no significant differences between allele, genotype and phenotype frequencies in the Croatian population and frequencies reported for Caucasian population. The results presented will be used for further studies investigating the role of mHAgs in hematopoietic stem cell transplantation.