Kristi Huik

University of Tartu · Department of Microbiology (ARMB)

A large proportion of the worlds population has some form of immunity against SARS-CoV-2, through either infection (natural), vaccination or both (hybrid). This retrospective cohort study used data on SARS-CoV-2, vaccination, and hospitalization from national health system from February 2020 to June 2022 and Cox regression modelling to compare thos...

Reservoirs of HIV maintained in anatomic compartments during antiretroviral therapy prevent HIV eradication. However, mechanisms driving their persistence and interventions to control them remain elusive. Here we report the presence of an inducible HIV reservoir within antigen-specific CD4⁺T cells in the central nervous system of a 59-year-old male...

Objectives: In Eastern Europe HIV-1 transmitted drug resistance (TDR) data, especially in integrase (IN) region is limited. In Estonia INSTI (Integrase Strand Transfer Inhibitors) TDR has been studied only prior to the INSTI scale-up in late 2010s. Current study aimed to determine the levels of protease (PR), reverse transcriptase (RT) and IN surv...

Despite the high number of SARS-CoV-2 infections, only a few cases of dual infection have been reported. Here, we describe a case of COVID-19 caused simultaneously by Delta and Omicron variants in an immunocompetent individual during the early emergence of Omicron variant. A 73-year-old man was hospitalized with suspected acute coronary syndrome, a...

Background HIV persistence during antiretroviral therapy (ART) is the principal obstacle to cure. Lymphoid tissue is a compartment for HIV, but mechanisms of persistence during ART and viral rebound when ART is interrupted are inadequately understood. Metabolic activity in lymphoid tissue of patients on long-term ART is relatively low, and increase...

The integrase strand transfer inhibitor (INSTI) dolutegravir is commonly used in combination antiretroviral therapy regimens and retains strong potency even with primary resistance mutations to some other INSTIs. Acquisition of accessory mutations to primary mutations results in significant increases in dolutegravir resistance. Previously, we repor...

Norovirus (NoV) is the leading cause of acute gastroenteritis (AGE) in many countries that have introduced universal rotavirus mass vaccination. This is the first study to report data on NoV strains in Estonia. We recruited 2249 children aged 0-18 years hospitalized for AGE in Estonian hospitals from 01 February 2015 to 31 August 2016. Norovirus ga...

Background Estonia has a typical Eastern European HIV epidemic where the most frequent co-infection is chronic hepatitis C (HCV). We aimed to describe the changes in HCV prevalence, the distribution of HCV genotypes (GT), and HCV treatment in Estonian people living with HIV over 15 years. Methods We used data of subjects included to the Estonian H...

Background: Estonia implemented the rotavirus (RV) vaccine into its national immunization program in July 2014. We aimed to determine circulating RV genotypes and the clinical profile by genotypes from February 1, 2015, to August 30, 2016, among children 0-18 years hospitalized due to rotavirus gastroenteritis (RVGE). Methods: During an observat...

Tuberculosis associated immune reconstitution inflammatory syndrome (TB-IRIS) is a serious complication of starting combination antiretroviral therapy (cART). TB-IRIS emerges early after cART initiation and is characterized by rapid expansions of TB-specific CD4+ T cells and high levels of inflammatory mediators driven by CD4+ T cells. The effects...

Background Estonia has a typical Eastern European HIV epidemic where the most frequent co-infection is chronic hepatitis C (HCV). We aimed to describe the changes in HCV prevalence, the distribution of HCV genotypes (GT), and HCV treatment in Estonian people living with HIV over 15 years. Methods We used data of subjects included to the Estonian HI...

Background: Estonia implemented rotavirus universal mass vaccination (RV UMV) in July 2014. We aimed to describe changes in acute gastroenteritis (AGE) hospitalization during RV seasons before (2007-2013) and after (2015-2018) RV UMV and compare patient profile of hospitalized AGE patients aged 0-18 years during first two consecutive RV seasons 20...

Extended-spectrum beta-lactamases (ESBL) and AmpC producing-Escherichia coli have spread worldwide, but data about ESBL-producing-E. coli in the Northern and Eastern regions of Europe is scant. The aim of this study has been to describe the phenotypical and molecular epidemiology of different ESBL/AmpC/Carbapenemases genes in E. coli strains isolat...

Background Serological assays to determine HIV incidence have contributed to estimates of HIV incidence, monitoring of HIV spread, and evaluation of prevention strategies. Two frequently used incidence assays are the Sedia HIV-1 LAg-Avidity EIA (LAg) and the Bio-Rad avidity incidence (BRAI) assays with a mean duration of recent infection (MDRI) of...

BACKGROUND: Serological assays to determine HIV incidence have contributed to estimates of HIV incidence, monitoring of HIV spread, and evaluation of prevention strategies. Two frequently used incidence assays are the Sedia HIV-1 LAg-Avidity EIA (LAg) and the Bio-Rad avidity incidence (BRAI) assays with a mean duration of recent infection (MDRI) of...

Background: Due to the widespread use of non-nucleoside reverse transcriptase inhibitors (NNRTI) as part of first-line therapies to curb the human immunodeficiency virus (HIV) epidemic in Eastern-European countries, transmitted drug resistance (TDR) is of serious concern in this region. Therefore, TDR and its associated risk factors were investiga...

We investigated the presence of a single nucleotide polymorphism designated rs12979860 in the interferon‐lambda‐4 (IFNλ4) gene among 345 people who inject drugs (PWID) and 495 blood donors to evaluate associations between the rs12979860 genotypes and HIV/HCV. The rs12979860 TT genotype was overrepresented among HIV+ PWID than HIV‐ PWID and blood do...

Objectives: Estonia has one the highest number of new HIV diagnoses in the European Union, mainly among injecting drug users and heterosexuals. Little is known of HIV incidence, which is crucial for limiting the epidemic. Using a recent HIV infection testing algorithm (RITA) assay, we aimed to estimate HIV incidence in 2013. Methods: All individ...

Background: We aimed to determine genetic relatedness between Staphylococcus epidermidis colonising breast milk (BM) and BM-fed neonates during the first month of life. Methods: S. epidermidis was isolated from stool and skin swabs of 20 healthy term and 49 preterm neonates hospitalised in neonatal intensive care unit and BM of mothers once a we...

Late-onset sepsis (LOS) in preterm neonates is increasingly reported to be associated with gut-colonizing Staphylococcus epidermidis. We aimed to describe the molecular epidemiology of S. epidermidis colonizing the gut of neonates hospitalized in two neonatal intensive care units. S. epidermidis from rectal swabs were typed by multilocus variable-n...

Objectives: We aimed to determine the rate of GBV-C viremia, seropositivity, and genotypes among people who inject drugs (PWID) and healthy volunteers in Estonia and to evaluate associations between GBV-C and sociodemographic factors, intravenous drug use, co-infections. Methods: The study included 345 Caucasian PWID and 118 healthy volunteers....

Intravenous drug use (IDU) is one of the most important transmission routes for blood borne viruses, including human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV). These infections alter the subset distributions of T cells; however, knowledge of such effects during HIV, HBV, and or HCV coinfection is limited. Th...

Objective: The role of CC chemokine receptor 5 (CCR5) and its ligand CCL5 on the pathogenesis of HIV infection has been well studied but not for HCV infection. Here, we investigated whether CCL5 haplotypes influence HIV and HCV seropositivity among 373 Caucasian people who inject drugs (PWID) from Estonia. Methods: Study included 373 PWID; 56% w...

Studies of associations between polymorphisms in CCL5 and acquisition of HIV-1 or HCV disease progression. (DOC)

Some individuals remain uninfected despite repeated exposure to HIV. This protection against HIV has been partly associated with altered T cell subset distributions and CCR5 expression levels. However, the majority of studies have been conducted in sexually exposed subjects. We aimed to assess whether HIV infection and intravenous drug use were ass...

Taust ja eesmärk. Inimese immuunpuudulikkuse viiruse (HIV) ja C-hepatiidi viirusega (HCV) nakatumist mõjutavad paljud tegurid, sh inimese geneetilised markerid. Uuringud on kirjeldanud polümorfisme erinevates HIV patogeneesiga seotud geenides (nt CCR5, CCL3L1), mis mõjutavad seksuaalsel teel HIVga nakatumist. Samas on vähe andmeid selle kohta, kuid...

HIV-1 drug resistance mutations (DRMs) and substitutions were assessed after the failure of the first line non-nucleoside reverse transcriptase inhibitors (NNRTIs) + 2 nucleoside/nucleotide reverse transcriptase inhibitors (NRTIs) treatment regimens (efavirenz (EFV) + 3TC + zidovudine (ZDV) vs. EFV + 3TC + ddI) among the HIV-1 CRF06_cpx infected su...

Estonia is experiencing the new Eastern Europe human immunodeficiency virus (HIV) epidemic, with the highest incidence of new infections in the EU. We describe demographic changes, HIV-related laboratory parameters and co-infections during the concentrated HIV epidemic using the Estonian HIV Cohort Study (E-HIV) database, founded in 2009. All 3750...

Wohlfahrtiimonas chitiniclastica is a rare human pathogen mostly associated with parasitic flies. This is the report on W. chitiniclastica infection in the soft tissue and bone at a 58°N latitude in the northern temperate climate zone. The importance of correct identification of clinically relevant bacteria is highlighted.

The aim of this study was to compare the prevalence of different virulence factor (VF) genes in extended-spectrum beta-lactamase (ESBL) producing Escherichia coli strains isolated from the Baltic Sea region. A total of 432 strains of phenotypically ESBL positive E. coli were collected from 20 institutions located in Estonia, Latvia, Lithuania, and...

The influence of the diversity of CCR5 on HIV susceptibility and disease progression has been clearly demonstrated but how the variability of this gene influences the HIV tropism is poorly understood. We investigated whether CCR5 haplotypes are associated with HIV tropism in a Caucasian population. We evaluated 161 HIV-positive subjects in a cross-...

The presence of transmitted drug resistance (TDR) in treatment naive HIV-1 positive subjects is of concern, especially in countries of former Soviet Union in which the number of subjects exposed to antiretrovirals (ARV) has exponentially increased during the last decade. We assessed the rate of TDR among newly diagnosed subjects in Estonia in 2010...

Up to 90% HIV-1 positive intravenous drug users (IDUs) are co-infected with HCV. Although best recognized for its function as a major co-receptor for cell entry of HIV, CC chemokine receptor 5 (CCR5) has also been implicated in the pathogenesis of HCV infection. Here, we investigated whether CCR5 haplotypes influence HIV-1 and HCV seropositivity am...

Background: Coagulase-negative staphylococci (CoNS) are the first colonizers of gastrointestinal tract (GIT) and the commonest cause of late-onset sepsis (LOS) in preterm neonates. Intravascular catheters are considered a major source of CoNS bacteremia. However, several cases of LOS remain without an identified source. To elucidate whether GIT co...

Group A rotaviruses (RVA) are a major cause of acute gastroenteritis in children ≤ 5 y worldwide which could be prevented with two recently introduced vaccines - monovalent Rotarix (live-attenuated G1P[8] strain) and pentavalent RotaTeq (human-bovine reassortant containing serotypes G1, G2, G3, G4 and P[8]). Prior to implementation of vaccines into...

Natural polymorphisms of HIV-1, often associated with drug resistance, are widely described in protease and reverse transcriptase regions but data on their presence in the integrase region, especially in non-B subtypes, are still very limited. We aimed to characterize naturally occurring polymorphisms in the integrase region in 104 treatment-naive...

Human immunodeficiency virus (HIV)-1 transmitted drug resistance in the drug-naïve population is of growing relevance in Estonia, where the number of antiretroviral (ARV) treatment-experienced subjects has been exponentially increasing during the last 10 y. The aim of this study was to estimate the rate of transmitted drug resistance among newly di...

A high copy number of CCL3L1, the most potent human immunodeficiency virus (HIV)-suppressive chemokine, associates with reduced HIV susceptibility. Whether CCL3L1 influences acquisition of multiple blood-borne infections (eg, hepatitis C virus [HCV], HIV, and hepatitis B virus [HBV] infections), which occur commonly among injection drug users (IDUs...

All non-B HIV-1 subtypes and circulating recombinant forms (CRFs) are characterized by several polymorphisms in protease (PR) region. In addition, in recent years the increasing use of antiretroviral treatment (ART) has rapidly raised the spread of transmitted drug resistance. We aimed to determine the presence of naturally occurring polymorphisms...

Segmental copy-number polymorphisms represent a significant component of human genetic variation and are likely to contribute to disease susceptibility. Chemokine ligand 3-like 1 (CCL3L1), is a member of the chemokine family and encoded by a variable copy-number of genes. It is a natural ligand of CCR5 and thereby plays an important role HIV-1/AIDS...