Teemu Smura

Zika Virus Infection with Prolonged Maternal Viremia and Fetal Brain Abnormalities

The current outbreak of Zika virus (ZIKV) infection has been associated with an apparent increased risk of congenital microcephaly. We describe a case of a pregnant woman and her fetus infected with ZIKV during the 11th gestational week. The fetal head circumference decreased from the 47th percentile to the 24th percentile between 16 and 20 weeks of gestation. ZIKV RNA was identified in maternal serum at 16 and 21 weeks of gestation. At 19 and 20 weeks of gestation, substantial brain abnormalities were detected on ultrasonography and magnetic resonance imaging (MRI) without the presence of microcephaly or intracranial calcifications. On postmortem analysis of the fetal brain, diffuse cerebral cortical thinning, high ZIKV RNA loads, and viral particles were detected, and ZIKV was subsequently isolated.

Zika virus infection in a traveller returning from the Maldives, June 2015

We report a Zika virus (ZIKV) infection in a patient with fever and rash after returning to Finland from Maldives, June 2015. The patient had dengue virus (DENV) IgG and IgM antibodies but pan-flavivirus RT-PCR and subsequent sequencing showed presence of ZIKV RNA in urine. Recent association of ZIKV with microcephaly highlights the need for laboratory differentiation of ZIKV from DENV infection and the circulation of ZIKV in areas outside its currently known distribution range.

Recent Zika Virus Isolates Induce Premature Differentiation of Neural Progenitors in Human Brain Organoids

The recent Zika virus (ZIKV) epidemic is associated with microcephaly in newborns. Although the connection between ZIKV and neurodevelopmental defects is widely recognized, the underlying mechanisms are poorly understood. Here we show that two recently isolated strains of ZIKV, an American strain from an infected fetal brain (FB-GWUH-2016) and a closely-related Asian strain (H/PF/2013), productively infect human iPSC-derived brain organoids. Both of these strains readily target to and replicate in proliferating ventricular zone (VZ) apical progenitors. The main phenotypic effect was premature differentiation of neural progenitors associated with centrosome perturbation, even during early stages of infection, leading to progenitor depletion, disruption of the VZ, impaired neurogenesis, and cortical thinning. The infection pattern and cellular outcome differ from those seen with the extensively passaged ZIKV strain MR766. The structural changes we see after infection with these more recently isolated viral strains closely resemble those seen in ZIKV-associated microcephaly.

5' noncoding region alone does not unequivocally determine genetic type of human rhinovirus strains.

During the last couple of years there has been a delightful increase in interest in genetic typing of human rhinoviruses. This is to a large extent due to the discovery of a proposed novel clade, human rhinovirus C (HRV-C). As a consequence, new methods have been reported aiming at unequivocal distinction of traditional HRV prototype strains as well as the newly found uncultivable HRV-C strains. We read with interest the article by Kiang and coworkers (2) describing reverse transcription-PCR-sequencing applications for genetic typing of human rhinoviruses targeting the 5′noncoding region (5′ NCR). A similar approach with largely similar results was published earlier (6). Relatively conserved areas within this region enable broad-spectrum primer design for sensitive methods. However, there are several issues to consider when using the 5′ NCR for genetic typing of HRV. Current taxonomy and classification of picornaviruses are based on capsid region coding sequences. On the basis of this region, a group of previously characterized novel HRV strains form one distinct clade (5, 7) (Fig. ​(Fig.1A),1A), a fact that has also been the basis of the proposal of the Picornavirus Study Group to form a new species, HRV-C, within the Enterovirus genus (4). However, in the article by Kiang et al., on the basis of the partial 5′ NCR sequences, the designated HRV-C strains clustered within the HRV-A clade (2). In contrast, the strains labeled HRV-C in this article formed a clade of their own. As a consequence, because 5′ NCR sequences do not segregate the designated HRV-C from HRV-A (Fig. ​(Fig.1B),1B), they should not be used for typing of new strains. Nevertheless, this region is quite suitable for selected topics of molecular epidemiology, such as analysis of short-term transmission routes (1, 8) or tentative prediction of genetic type as in human enteroviruses (HEV) (9). The sequences nominated as HRV-C by Kiang et al. (2) and by Lee et al. (6) form a new clade in the 5′ NCR. The exact taxonomic position of this clade should be determined according to the clustering of these strains in the capsid region. Clearly, it is divergent from all known HRV and HEV clades in the 5′ NCR, but the decision on whether the strains represent HRV-C or some other picornavirus group cannot be made on the basis of the 5′ NCR alone. FIG. 1. Phylogenetic trees in the VP4/VP2 capsid coding region (A) and in the 5′ NCR (B) of different species of the enterovirus genus showing different clustering of the species in the two regions. Trees were constructed with MEGA4 using the neighbor-joining ... The area close to the beginning of the open reading frame in the 5′ NCR is known to be a recombination hot spot in HEV. Although frequent recombination has not yet been shown for HRV, the analysis of the complete genome sequence data of all HRV prototype strains has not yet been published. Furthermore, the number of completely sequenced genomes of circulating HRV strains has remained low and is too low to conclude that the evolution in the 5′ NCR is always congruent with that of the capsid. Therefore, we would see phylogenetic analysis of the 5′ NCR of HRV as a welcome addition to HRV research, but not a surrogate of capsid coding sequence-based typing.

Sindbis virus as a human pathogen-epidemiology, clinical picture and pathogenesis.

Sindbis virus (SINV; family Togaviridae, genus Alphavirus) is an enveloped RNA virus widely distributed in Eurasia, Africa, Oceania and Australia. SINV is transmitted among its natural bird hosts via mosquitoes. Human disease caused by SINV infection has been reported mainly in South Africa and in Northern Europe. Vector mosquito abundance affects the annual incidence of SINV infections with occasional outbreaks of up to 1500 patients. Symptoms include fever, malaise, rash and musculoskeletal pain. In a significant portion of patients the debilitating musculoskeletal symptoms persist for years. Chronic disease after SINV infection shares many features with autoimmune diseases. Currently there is no specific treatment available. Recently SINV infections have been detected outside the previously known distribution range. In this article we will summarize the current knowledge on epidemiology, clinical disease and pathogenesis of SINV infection in man. Copyright

Sindbis virus as a human pathogenepidemiology, clinical picture and pathogenesis

Sindbis virus (SINV; family Togaviridae, genus Alphavirus) is an enveloped RNA virus widely distributed in Eurasia, Africa, Oceania and Australia. SINV is transmitted among its natural bird hosts via mosquitoes. Human disease caused by SINV infection has been reported mainly in South Africa and in Northern Europe. Vector mosquito abundance affects the annual incidence of SINV infections with occasional outbreaks of up to 1500 patients. Symptoms include fever, malaise, rash and musculoskeletal pain. In a significant portion of patients the debilitating musculoskeletal symptoms persist for years. Chronic disease after SINV infection shares many features with autoimmune diseases. Currently there is no specific treatment available. Recently SINV infections have been detected outside the previously known distribution range. In this article we will summarize the current knowledge on epidemiology, clinical disease and pathogenesis of SINV infection in man. Copyright

Amino acids of coxsackie B5 virus are critical for infection of the murine insulinoma cell line, MIN-6

It was shown recently that 15 successive passages of a laboratory strain of the Coxsackie B virus 5 in a mouse pancreas (CBV‐5‐MPP) resulted in apparent changes in the virus phenotype, which led to the capacity to induce a diabetes‐like syndrome in mice. For further characterization of islet cell interactions with a passaged virus strain, a murine insulinoma cell line, MIN‐6, was selected as an experimental model. The CBV‐5‐MPP virus strain was not able to replicate in MIN‐6 cells in vitro but required adaptation over a few days for progeny production and the generation of cytopathic effects. In order to determine the genetic characteristics required for virus growth in MIN‐6 cells, the whole genome of the MIN‐6‐adapted virus variant was sequenced, and critical amino acids were identified by comparing the sequence with that of a virus strain passaged repeatedly in the mouse pancreas. The results of site‐directed mutagenesis demonstrated that only one residue, amino acid 94 of VP1, is a major determinant for virus adaptation to MIN‐6 cells. J. Med. Virol. 81:296–304, 2009.

Recombination in the Evolution of Enterovirus C Species Sub-Group that Contains Types CVA-21, CVA-24, EV-C95, EV-C96 and EV-C99

Genetic recombination is considered to be a very frequent phenomenon among enteroviruses (Family Picornaviridae, Genus Enterovirus). However, the recombination patterns may differ between enterovirus species and between types within species. Enterovirus C (EV-C) species contains 21 types. In the capsid coding P1 region, the types of EV-C species cluster further into three sub-groups (designated here as A–C). In this study, the recombination pattern of EV-C species sub-group B that contains types CVA-21, CVA-24, EV-C95, EV-C96 and EV-C99 was determined using partial 5′UTR and VP1 sequences of enterovirus strains isolated during poliovirus surveillance and previously published complete genome sequences. Several inter-typic recombination events were detected. Furthermore, the analyses suggested that inter-typic recombination events have occurred mainly within the distinct sub-groups of EV-C species. Only sporadic recombination events between EV-C species sub-group B and other EV-C sub-groups were detected. In addition, strict recombination barriers were inferred for CVA-21 genotype C and CVA-24 variant strains. These results suggest that the frequency of inter-typic recombinations, even within species, may depend on the phylogenetic position of the given viruses.

High Seroprevalence of Enterovirus Infections in Apes and Old World Monkeys

To estimate population exposure of apes and Old World monkeys in Africa to enteroviruses (EVs), we conducted a seroepidemiologic study of serotype-specific neutralizing antibodies against 3 EV types. Detection of species A, B, and D EVs infecting wild chimpanzees demonstrates their potential widespread circulation in primates.

The evolution of Vp1 gene in enterovirus C species sub-group that contains types CVA-21, CVA-24, EV-C95, EV-C96 and EV-C99.

Genus Enterovirus (Family Picornaviridae,) consists of twelve species divided into genetically diverse types by their capsid protein VP1 coding sequences. Each enterovirus type can further be divided into intra-typic sub-clusters (genotypes). The aim of this study was to elucidate what leads to the emergence of novel enterovirus clades (types and genotypes). An evolutionary analysis was conducted for a sub-group of Enterovirus C species that contains types Coxsackievirus A21 (CVA-21), CVA-24, Enterovirus C95 (EV-C95), EV-C96 and EV-C99. VP1 gene datasets were collected and analysed to infer the phylogeny, rate of evolution, nucleotide and amino acid substitution patterns and signs of selection. In VP1 coding gene, high intra-typic sequence diversities and robust grouping into distinct genotypes within each type were detected. Within each type the majority of nucleotide substitutions were synonymous and the non-synonymous substitutions tended to cluster in distinct highly polymorphic sites. Signs of positive selection were detected in some of these highly polymorphic sites, while strong negative selection was indicated in most of the codons. Despite robust clustering to intra-typic genotypes, only few genotype-specific ‘signature’ amino acids were detected. In contrast, when different enterovirus types were compared, there was a clear tendency towards fixation of type-specific ‘signature’ amino acids. The results suggest that permanent fixation of type-specific amino acids is a hallmark associated with evolution of different enterovirus types, whereas neutral evolution and/or (frequency-dependent) positive selection in few highly polymorphic amino acid sites are the dominant forms of evolution when strains within an enterovirus type are compared.