Retrospective review and current knowledge on the occurrence of West Nile virus in mosquito vectors, reservoirs and hosts in Slovakia (Central Europe).

West Nile virus (WNV) is a mosquito-borne flavivirus (the genus Flavivirus) representing a medical and veterinary public health concern. Birds are the most important reservoirs. Culicine mosquitoes transmit WNV to vertebrate hosts (including horses and humans) and migratory birds play role in its long-distance transport. Slovakia is geographically localised at the crossroad of migration routes connecting South Europe and Africa with breeding localities in the Western, Northern, Central and Eastern Europe and Siberia. This review summarizes historical and present knowledge on WNV in Slovakia during a period of more than fifty years. Five European mosquito species capable to transmit WNV are native in Slovakia. Based on recent research results, the major role in the WNV transmission is attributed to Culex mosquitoes, which are also the most abundant species. Virus isolates from birds that succumbed to WNV infection are genetically close to Central European strains. Historical and recent results point out, that WNV circulates in the population of vectors, reservoirs and hosts for decades. Although West Nile fever epidemics in Slovakia were not reported yet, virus isolation, molecular detection and serological findings in reservoirs and hosts confirm that sporadic cases occur. Furthermore, the first autochthonous human case may indicate favourable conditions for WNV transmission to humans. The climate change and precipitation anomalies may favour to increase vector abundance, hence increase the chance of WNV epidemics. This review highlights an urgent need of a countrywide surveillance program aimed on the WNV occurrence in vectors and reservoirs in Slovakia. Keywords: West Nile virus; flavivirus; vector-borne pathogen; arbovirus.

Genetic variability of pig and human rotavirus group A isolates from Slovakia.

The aim of this work was the genetic typing of RVA isolates originating from pigs and human patients in Slovakia. Seventy-eight rectal swabs from domestic pigs and 30 stool samples from humans were collected. The whole VP7 (G genotypes), VP6 (I genotypes) and partial VP4 (P genotypes) ORFs were amplified by RT-PCR. Genetic variability was higher amongst porcine sequences, where four G genotypes (G3, G4, G5, G11), two P genotypes (P[6], P[13]) and one I5 genotype were detected. Human RVA strains were represented by two G genotypes (G1, G3), two I genotypes (I1, I2), and one P genotype (P[8]). Genetic analysis did not show a relationship between Slovakian porcine and human RVA strains, but phylogenetic grouping of some Slovakian porcine sequences with Hungarian human sequences in both G and P genotypes was observed.

Systemic immune response of gnotobiotic mice infected with porcine circovirus type 2 after administration of Lactobacillus reuteri L26 Biocenol™.

In our previous study we confirmed an antiviral activity of probiotic Lactobacillus reuteri L26 which was mediated by stimulation of local intestinal immunity. The aim of this paper was to evaluate the influence of L. reuteri L26 on the systemic immune response in gnotobiotic mice infected with porcine circovirus type 2 (PCV2). A total of 30 germ-free mice were divided into 3 groups and animals in noninfected and infected control groups (NC and IC; n=10) received sterile de Man-Rogosa-Sharpe broth for 7 days and animals in experimental group L+PCV (n=10) were inoculated with L. reuteri L26. Subsequently, mice in L+PCV and IC groups were infected with PCV2; however, mice in the control group received virus cultivation medium (mock). The results showed an increase of percentage of cytotoxic cells (CD8+ and CD49b+CD8-) and oxidative burst of phagocytes, up-regulation of the gene expression of RANTES, granulocyte-macrophage colony-stimulating factor, interferon-γ and immunoglobulin A in blood above all in the later phase of infection (14 dpi) in L+PCV group accompanied by higher load of PCV2 in the serum. These findings indicate that L. reuteri L26 has a potential to induce systemic immune reaction, but in gnotobiotic mice immune stimulation can increase virus replication.

Influence of Lactobacillus reuteri L26 Biocenol™ on immune response against porcine circovirus type 2 infection in germ-free mice.

Probiotic bacteria are frequently used for prevention of bacterial infections of the gastrointestinal tract, but there are only limited studies on their efficacy against viral gut infections in animals. The aim of this study was to investigate the effect of probiotic Lactobacillus reuteri L26 BiocenolTM on the innate and adaptive immune responses in germ-free Balb/c mice, experimentally infected by porcine circovirus type 2 (PCV2), which confers immunosuppressive effect. A total of 30 six-week-old female mice were divided into 3 groups and animals in experimental group LPCV (n=10) were inoculated with L. reuteri L26, animals in the control group (C; n=10) and experimental group PCV (n=10) received sterile De Man-Rogosa-Sharpe broth for 7 days. Subsequently, mice from both experimental groups were infected with PCV2; however, mice in the control group received virus cultivation medium (mock). Virus load in faeces, ileum and mesenteric lymph nodes (MLN); as well as gene expression of selected cytokines, immunoglobulin A (IgA) and polymeric Ig receptor (PIgR) in the ileum, and percentage of CD8+, CD19+ and CD49b+CD8- cells in the MLN were evaluated. Our results showed that L. reuteri significantly decreased the amount of PCV2 in faeces and in the ileum, and up-regulated the gene expression of chemokines, interferon (IFN)-γ, IgA and PIgR in the ileum. Increased IFN-γ mRNA level was accompanied by higher proportion of natural killer cells and up-regulated IgA and PIgR gene expressions were in accordance with significantly higher percentage of CD19+ lymphocytes in the MLN. These findings indicate that probiotic L. reuteri has an antiviral effect on PCV2 in the intestine which is mediated by stimulation of local gut immune response.

Prevalence of porcine circovirus 2 infection in pig population in Slovakia.

The prevalence of porcine circovirus 2 (PCV-2) infection in the pig population in Slovakia was investigated. Sera from pigs suspected for post-weaning multisystemic wasting syndrome (PMWS) as well as clinically healthy pigs were tested for viral DNA and specific IgM and IgG antibodies. Pigs (n = 198) were categorized to weaning, grower and fattening ones and sows. The results showed that PCV-2 antibodies were present in 53.4% of PMWS-suspects, in 50.0% of healthy pigs and in 69.0% of sows. In PMWS-suspect grower pigs, 40.7% were positive for IgM+IgG antibodies and 22.2% for viral DNA. In PMWS-suspect fattening pigs, 50.0% were positive for IgM+IgG antibodies and 25.0% for viral DNA. In healthy fattening pigs, almost 90.0% were positive for IgG antibodies and 38.5% for viral DNA. The highest proportion of PMWS-suspects was in grower pigs and specific antibodies were increasing with the age of pigs. A combination of positivities for IgG+IgM antibodies and viral DNA was a highly significant marker of PMWS. Viral DNA was detected in seropositive as well as seronegative PMWS-suspects. Overall, in all categories of pigs tested, specific antibodies and viral DNA were detected in 54.0% and 35.5%, respectively.