A longitudinal study on SARS-CoV-2 seroconversion, reinfection and neutralisation spanning several variant waves and vaccination campaigns, Heinsberg, Germany, April 2020 to November 2022.

BackgroundSince its emergence in December 2019, over 700 million people worldwide have been infected with SARS-CoV-2 up to May 2024. While early rollout of mRNA vaccines against COVID-19 has saved many lives, there was increasing immune escape of new virus variants. Longitudinal monitoring of population-wide SARS-CoV-2 antibody responses from regular sample collection irrespective of symptoms provides representative data on infection and seroconversion/seroreversion rates.AimTo examine adaptive and cellular immune responses of a German SARS-CoV-2 outbreak cohort through several waves of infection with different virus variants.MethodsUtilising a 31-month longitudinal seroepidemiological study (n = 1,446; mean age: 50 years, range: 2-103) initiated during the first SARS-CoV-2 superspreading event (February 2020) in Heinsberg, Germany, we analysed acute infection, seroconversion and virus neutralisation at five follow-up visits between October 2020 and November 2022; cellular and cross-protective immunity against SARS-CoV-2 Omicron variants were also examined.ResultsSARS-CoV-2 spike (S)-specific IgAs decreased shortly after infection, while IgGs remained stable. Both increased significantly after vaccination. We predict an 18-month half-life of S IgGs upon infection. Nucleocapsid (N)-specific responses declined over 12 months post-infection but increased (p < 0.0001) during Omicron. Frequencies of SARS-CoV-2-specific TNF-alpha+/IFN-gamma+ CD4+ T-cells declined over 12 months after infection (p < 0.01). SARS-CoV-2 S antibodies and neutralisation titres were highest in triple-vaccinated participants infected between April 2021 and November 2022 compared with infections between April 2020 and January 2021. Cross neutralisation against Omicron BQ.1.18 and XBB.1.5 was very low in all groups.ConclusionInfection and/or vaccination did not provide the population with cross-protection against Omicron variants.

Non-structural genes of novel lemur adenoviruses reveal codivergence of virus and host.

Adenoviruses (AdVs) are important human and animal pathogens and are frequently used as vectors for gene therapy and vaccine delivery. Surprisingly, there are only scant data regarding primate AdV origin and evolution, especially in the most basal primate hosts. We detect and sequence AdVs from faeces of two Madagascan lemur species. Complete genome sequence analyses define a new AdV species with a particularly large gene encoding a protein of unknown function in the early gene region 3. Unexpectedly, the new AdV species is not most similar to human or other simian AdVs but to bat adenovirus C. Genome characterisation shows signals of virus-host codivergence in non-structural genes, which show lower diversity than structural genes. Outside a lemur species mixing zone, recombination less frequently separates structural genes, as in human adenovirus C. The evolutionary history of lemur AdVs likely involves both a host switch and codivergence with the lemur hosts.

Infection fatality rate of SARS-CoV2 in a super-spreading event in Germany.

A SARS-CoV2 super-spreading event occurred during carnival in a small town in Germany. Due to the rapidly imposed lockdown and its relatively closed community, this town was seen as an ideal model to investigate the infection fatality rate (IFR). Here, a 7-day seroepidemiological observational study was performed to collect information and biomaterials from a random, household-based study population. The number of infections was determined by IgG analyses and PCR testing. We found that of the 919 individuals with evaluable infection status, 15.5% (95% CI:[12.3%; 19.0%]) were infected. This is a fivefold higher rate than the reported cases for this community (3.1%). 22.2% of all infected individuals were asymptomatic. The estimated IFR was 0.36% (95% CI:[0.29%; 0.45%]) for the community and 0.35% [0.28%; 0.45%] when age-standardized to the population of the community. Participation in carnival increased both infection rate (21.3% versus 9.5%, p < 0.001) and number of symptoms (estimated relative mean increase 1.6, p = 0.007). While the infection rate here is not representative for Germany, the IFR is useful to estimate the consequences of the pandemic in places with similar healthcare systems and population characteristics. Whether the super-spreading event not only increases the infection rate but also affects the IFR requires further investigation.

Exhaustive TORCH Pathogen Diagnostics Corroborate Zika Virus Etiology of Congenital Malformations in Northeastern Brazil.

The Latin American 2015-2016 Zika virus (ZIKV) outbreak was associated with an increase in microcephaly predominantly in northeastern Brazil. To comparatively investigate infectious causes of congenital malformations, we performed a nested case-control study in 32 mothers of cases of suspected congenital Zika syndrome (CZS) and 160 age-matched controls from Bahia, northeastern Brazil. We collected clinical and imaging data and assessed past exposure to ZIKV, Chikungunya virus (CHIKV), dengue virus, and 8 established TORCH (Toxoplasma gondii, Treponema pallidum, rubella virus, cytomegalovirus, herpes simplex virus 1 [HSV-1] and HSV-2, varicella-zoster virus, parvovirus B19) pathogens using multiple serological tests. Heterogeneous symptoms prevented unequivocal diagnosis of CZS on clinical grounds. Only ZIKV and CHIKV seroprevalence rates differed significantly between cases and controls (93.8% versus 67.8% for ZIKV [Fisher's exact text, P = 0.002] and 20.7% versus 8.2% for CHIKV [χ2, P = 0.039]). High ZIKV seroprevalence rates in cases could not be explained by previous dengue virus infections potentially eliciting cross-reactive antibody responses affecting ZIKV serological tests. In conditional logistic regression analyses, only ZIKV was significantly associated with congenital malformations (P = 0.030; odds ratio, 4.0 [95% confidence interval, 1.1 to 14.1]). Our data support an association between maternal ZIKV exposure and congenital malformations. Parallels between the discrepant ZIKV and CHIKV seroprevalence rates between cases and controls and similar seroprevalence rates between cases and controls for the sexually transmitted T. pallidum and HSV-2 may suggest the occurrence of predominantly vector-borne transmission in our study population. High seroprevalence of TORCH pathogens suggests that exhaustive diagnostics will be necessary in the aftermath of the ZIKV outbreak and provides baseline data for longitudinal studies on ZIKV pathogenesis.IMPORTANCE The Latin American Zika virus (ZIKV) outbreak had a major impact on reproductive health worldwide. The reasons for the massively increased reports of neonatal microcephaly in northeastern Brazil are still unclear. Beyond the technical limitations of laboratory diagnostics, unambiguous diagnosis of ZIKV as the cause of congenital malformations is hampered by similar clinical pictures elicited by other pathogens known as TORCH pathogens. We performed a case-control study comparing mothers of children with congenital malformations to age-matched controls from Salvador, Brazil, one of the areas most extensively affected by the ZIKV outbreak. The ZIKV and Chikungunya virus seroprevalence rates differed significantly, whereas the levels of maternal exposure to TORCH pathogens were similar between cases and controls. Our data support a link between maternal ZIKV infection and congenital malformations and suggest the occurrence of predominantly vector-borne ZIKV transmission in these cases. In addition, some highly prevalent TORCH pathogens may be misinterpreted as representative of ongoing ZIKV activity in the absence of exhaustive diagnostics in northeastern Brazil.

Assay optimization for molecular detection of Zika virus.

OBJECTIVE: To examine the diagnostic performance of real-time reverse transcription (RT)-polymerase chain reaction (PCR) assays for Zika virus detection. METHODS: We compared seven published real-time RT-PCR assays and two new assays that we have developed. To determine the analytical sensitivity of each assay, we constructed a synthetic universal control ribonucleic acid (uncRNA) containing all of the assays' target regions on one RNA strand and spiked human blood or urine with known quantities of African or Asian Zika virus strains. Viral loads in 33 samples from Zika virus-infected patients were determined by using one of the new assays. FINDINGS: Oligonucleotides of the published real-time RT-PCR assays, showed up to 10 potential mismatches with the Asian lineage causing the current outbreak, compared with 0 to 4 mismatches for the new assays. The 95% lower detection limit of the seven most sensitive assays ranged from 2.1 to 12.1 uncRNA copies/reaction. Two assays had lower sensitivities of 17.0 and 1373.3 uncRNA copies/reaction and showed a similar sensitivity when using spiked samples. The mean viral loads in samples from Zika virus-infected patients were 5 × 104 RNA copies/mL of blood and 2 × 104 RNA copies/mL of urine. CONCLUSION: We provide reagents and updated protocols for Zika virus detection suitable for the current outbreak strains. Some published assays might be unsuitable for Zika virus detection, due to the limited sensitivity and potential incompatibility with some strains. Viral concentrations in the clinical samples were close to the technical detection limit, suggesting that the use of insensitive assays will cause false-negative results.

Genetic variation and recombination in Aichi virus.

Aichi virus (AiV), a member of the genus Kobuvirus in the family Picornaviridae, causes gastroenteritis in humans. It was noted that AiV differs from other picornaviruses in its unusually high C content and a very high degree of genome-ordered RNA secondary structures. However, the genetic variability and mutational restrictions on a full-genome scale have not been studied. In addition to the available five complete AiV genomes, we determined here another five complete coding sequences of AiV sampled in Germany, 2004. Distinctive AiV genetic features included a low incidence of recombination along the genome without obvious hotspots or spared regions and very low rates of synonymous and non-synonymous variation, supporting an absence of AiV serotypes. In addition, the absence of recombination between AiV genotypes A and B suggested the existence of reproductive isolation between taxonomic units below the species level. In contrast to most other picornaviruses, AiV genomes strongly avoided the UpA dinucleotide, while there was no obvious selection against the CpG dinucleotide. AiV genomes also appeared to contain a codon usage bias (CUB) apparent as an effective number of codons of 39.5, which was amongst the most extreme among RNA viruses. A set of sequence scrambling algorithms was developed to determine the origin of CUB in AiV. While in most picornaviruses the genomic dinucleotide content contributed significantly to CUB, in AiV its extreme nucleotide content, i.e. 57 % third codon position C, was the main driving force behind the apparent CUB.

Human cardioviruses, meningitis, and sudden infant death syndrome in children.

Cardioviruses cause myocarditis and encephalomyelitis in rodents; human cardioviruses have not been ascribed to any disease. We screened 6,854 cerebrospinal fluid and 10 myocardium specimens from children and adults. A genotype 2 cardiovirus was detected from a child who died of sudden infant death syndrome, and 2 untypeable cardioviruses were detected from 2 children with meningitis.

Aichi virus shedding in high concentrations in patients with acute diarrhea.

We assessed Aichi virus shedding in patients with gastroenteritis and negative test results for other viral and bacterial infections. High concentrations of up to 1.32 × 1012 RNA copies/g stool were found in 10 (2.0%) of 499 outpatients sampled in northern Germany, 2004. These data substantiate Aichi virus pathogenicity in humans.

Novel human parechovirus from Brazil.

Human parechoviruses (HPeVs) were detected by reverse transcription-PCR in 16.1% of 335 stool samples from children <6 years of age with enteritis in Salvador, Brazil. Whole genome sequencing of 1 sample showed a novel HPeV that has been designated as HPeV8.