Human parvovirus 4 ‘PARV4’ remains elusive despite a decade of study

Abstract

Human parvovirus 4 (‘PARV4’) is a small DNA tetraparvovirus, first reported in 2005. In some populations, PARV4 infection is uncommon, and evidence of exposure is found only in individuals with risk factors for parenteral infection who are infected with other blood-borne viruses. In other settings, seroprevalence studies suggest an endemic, age-associated transmission pattern, independent of any specific risk factors. The clinical impact of PARV4 infection remains uncertain, but reported disease associations include an influenza-like syndrome, encephalitis, acceleration of HIV disease, and foetal hydrops. In this review, we set out to report progress updates from the recent literature, focusing on the investigation of cohorts in different geographical settings, now including insights from Asia, the Middle East, and South America, and discussing whether attributes of viral or host populations underpin the striking differences in epidemiology. We review progress in understanding viral phylogeny and biology, approaches to diagnostics, and insights that might be gained from studies of closely related animal pathogens. Crucial questions about pathogenicity remain unanswered, but we highlight new evidence supporting a possible link between PARV4 and an encephalitis syndrome. The unequivocal evidence that PARV4 is endemic in certain populations should drive ongoing research efforts to understand risk factors and routes of transmission and to gain new insights into the impact of this virus on human health.

Human Parvovirus 4: A harmless bystander or a pathogen of severe acute respiratory illness

“…Genotype-2 (formerly known as PARV5) has been identified in European and North American cohorts (Matthews et al, 2017;Simmonds et al, 2008;Fryer et al, 2007b). It was also the predominant strain reported from Asia (Matthews et al, 2017;Benjamin et al, 2011). In one of our earlier studies we also found genotype 2 in samples from cases of encephalitis (Prakash et al, 2015).There is a high similarity in strains of genotype 2 identified the world over.…”

“…Genotype 2 was the only circulating genotype detected in the present study. Genotype-2 (formerly known as PARV5) has been identified in European and North American cohorts (Matthews et al, 2017;Simmonds et al, 2008;Fryer et al, 2007b). It was also the predominant strain reported from Asia (Matthews et al, 2017;Benjamin et al, 2011).…”

“…Parvovirus 4 (PARV4) is a newly discovered human Parvovirus, first reported in 2005 in serum of intravenous drug users infected with hepatitis B virus (Jones et al, 2005). PARV4 is a single stranded non-enveloped DNA virus belonging to the Parvoviridae family of genus Tetraparvovirus (Matthews et al, 2017). PARV4 infects a diverse range of hosts and has been classified into 3 genotypes; 1-3.…”

Parvovirus B19 and Human Parvovirus 4 Encode a Homologous "X Protein" in a Reading Frame Overlapping the VP1 Capsid Gene

“…B19V causes several diseases in humans, such as fifth disease in children, cardiomyopathy, and persistent anemia in immunocompromised persons [4]. PARV4 is not formally associated to any disease, despite suspicions that it may cause encephalitis or accelerate HIV progression [5]. B19V and PARV4 respectively belong to the genera erythroparvovirus and tetraparvovirus, which are closely related [2]; other species in these genera infect a variety of mammals (see Fig 1).…”

PARV4 found in wild chimpanzee faeces: an alternate route of transmission?

“…The first primate tetraparvovirus probably emerged in the 1980´s together with the appearance of the HIV virus infection [1] and, so far, three phylogenetically distinct genotypes have been described in humans. Since first human PARV-4 description in 2005, the epidemiology data are growing and were recently reviewed by Matthews et al [2]. Human PARV4 G1 and G2 are predominant in Europe, North America and Middle East [3][4][5][6][7][8][9][10], and are most often described in patients with a history of parenteral drugs application suffering from HIV, HCV or HBV infections [10,11].…”