Impact of Natural or Synthetic Singletons in the Capsid of Human Bocavirus 1 on Particle Infectivity and Immunoreactivity.

Human bocavirus 1 (HBoV1) is a parvovirus that gathers increasing attention due to its pleiotropic role as a pathogen and emerging vector for human gene therapy. Curiously, albeit a large variety of HBoV1 capsid variants has been isolated from human samples, only one has been studied as a gene transfer vector to date. Here, we analyzed a cohort of HBoV1-positive samples and managed to PCR amplify and sequence 29 distinct HBoV1 capsid variants. These differed from the originally reported HBoV1 reference strain in 32 nucleotides or four amino acids, including a frequent change of threonine to serine at position 590. Interestingly, this T590S mutation was associated with lower viral loads in infected patients. Analysis of the time course of infection in two patients for up to 15 weeks revealed a gradual accumulation of T590S, concurrent with drops in viral loads. Surprisingly, in a recombinant vector context, T590S was beneficial and significantly increased titers compared to that of T590 variants but had no major impact on their transduction ability or immunoreactivity. Additional targeted mutations in the HBoV1 capsid identified several residues that are critical for transduction, capsid assembly, or DNA packaging. Our new findings on the phylogeny, infectivity, and immunoreactivity of HBoV1 capsid variants improve our understanding of bocaviral biology and suggest strategies to enhance HBoV1 gene transfer vectors.IMPORTANCE The family of Parvoviridae comprises a wide variety of members that exhibit a unique biology and that are concurrently highly interesting as a scaffold for the development of human gene therapy vectors. A most notable example is human bocavirus 1 (HBoV1), which we and others have recently harnessed to cross-package and deliver recombinant genomes derived from another parvovirus, the adeno-associated virus (AAV). Here, we expanded the repertoire of known HBoV1 variants by cloning 29 distinct HBoV1 capsid sequences from primary human samples and by analyzing their properties as AAV/HBoV1 gene transfer vectors. This led to our discovery of a mutational hot spot at HBoV1 capsid position 590 that accumulated in two patients during natural infection and that lowers viral loads but increases vector yields. Thereby, our study expands our current understanding of HBoV1 biology in infected human subjects and concomitantly provides avenues to improve AAV/HBoV1 gene transfer vectors.

[Primary hyperoxaluria type 1-a rare hereditary metabolic disorder as cause of livedo racemosa]. / Primäre Hyperoxalurie Typ 1 ­ eine seltene hereditäre Stoffwechselstörung als Ursache einer Livedo racemosa.

Livedo racemosa is characterized by a bizarrely configurated lightning figure-like appearance with striated to reticulated, livid erythematous macules and results from a reduced perfusion of the respective skin area, which can have different underlying pathophysiologies. A rare but relevant cause, especially in young patients with end-stage kidney failure, is primary hyperoxaluria type 1 (PH1), a hereditary metabolic disorder in which oxalate accumulates in the body.

[Dermato-neuro syndrome-an acute and life-threatening complication of scleromyxedema Arndt-Gottron]. / Dermato-neurologisches Syndrom ­ eine akute und lebensbedrohliche Komplikation des Skleromyxödems Arndt-Gottron.

Scleromyxedema Arndt-Gottron is the systemic variant of lichen myxedematosus in which mucin accumulation occurs in the dermis. The disease is usually chronically progressive and extracutaneous manifestations or complications are possible. The pathogenesis is unknown and the disease is usually associated with monoclonal gammopathy. High-dose intravenous immunoglobulins (IVIg) are considered to be an effective therapy. We report the case of a patient who developed dermato-neuro syndrome following an interruption of IVIg treatment and a SARS-CoV­2 infection. A similar episode occurred 2 years earlier in association with an influenza A infection. Dermato-neuro syndrome is a potentially lethal neurological complication which is characterized by fever, delirium, convulsions, and coma.

Severe Human Bocavirus 1 Respiratory Tract Infection in an Immunodeficient Child With Fatal Outcome.

We report a case of lower respiratory tract infection with human bocavirus 1 (HboV1) in an immunodeficient 6-month-old boy leading to respiratory failure with fatal outcome. Polymerase chain reaction of serum/tracheal secretions revealed exceptionally high HboV1-DNA levels and immunoassays showed seroconversion indicating an acute primary HboV1 infection. All assays for other pathogens were negative, strongly suggesting that HboV1 was the causative agent in this case.