Recently discovered respiratory viruses were detected in 19 (9.2%) of 205 nasal swab specimens from children in Brazil with respiratory illnesses. Five each were positive for human metapneumovirus (HMPV) alone and human bocavirus (HBoV) alone, 3 for human coronaviruses (HCoV-HKU1 or -NL63) alone, and 6 for more than 1 recently discovered virus.

About 40 years ago, the large and small tumor antigens (LT-Ag and sT-Ag) of the polyomavirus (PyVs) simian vacuolating virus 40 have been identified and characterized. To date, it is well known that all the discovered human PyVs (HPyVs) encode these 2 multifunctional and tumorigenic proteins, expressed at viral replication early stage. The 2 T-Ags are able to transform cells both in vitro and in vivo and seem to play a distinct role in the pathogenesis of some tumors in humans. In addition, they are involved in viral DNA replication, transcription, and virion assembly. This short review focuses on the structural and functional features of the HPyVs’ LT-Ag and sT-Ag, with special attention to their transforming properties.

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Human bocavirus (HBoV) is an emerging virus and has been detected worldwide, especially in pediatric patients with respiratory and gastrointestinal infection. In this study, we describe HBoV prevalence, genotypes circulation and DNA shedding, in stool samples from children up to two years of age in Brazil. During 2016 and 2017, 886 acute gastroenteritis (AGE) stool samples from ten Brazilian states were analyzed by TaqMan®-based qPCR, to detect and quantify HBoV. Positive samples were genotyped by sequencing the VP1/2 overlap region, followed by phylogenetic analysis and co-infections were accessed by screening other gastroenteric viruses. HBoV was detected in 12.4% (n = 110) of samples, with viral load ranging from 1.6 × 102 to 1.2 × 109 genome copies per gram of stool. From these, co-infections were found in 79.1%, and a statistically lower HBoV viral load was found compared to viral loads of rotavirus, norovirus and adenovirus in double infected patients (p < 0.05). No significant differences were found between HBoV viral load in single or co-infections, age groups or genotypes. Phylogenetic analysis identified the circulation of HBoV-1 in 38%, HBoV-2 in 40% and HBoV-3 in 22%. Continuous HBoV monitoring is needed to clarify its role in diarrhea disease, especially in the absence of classic gastroenteric viruses.

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine cancer, with approximately 80% of cases associated with Merkel cell polyomavirus (MCPyV). The lack of information concerning its occurrence in non-MCC immunosuppressed populations led to the investigation of MCPyV DNA in saliva and oral biopsies from 60 kidney allograft recipients and 75 non-transplanted individuals (control group). In contrast to herpesviruses, which was also investigated (CMV, HHV-6A, and B, HHV-7) MCPyV was detected predominantly in patients with oral lesions (gingivitis and/or periodontitis) of both transplanted and non-transplanted groups (P=0.016) and in the saliva of the transplanted group (P=0.009). MCPyV co-detection with CMV (P=0.048), and HHV-6 (P=0.020) in the saliva of transplanted patients requires further investigation on a possible role of co-infection.

In general, SARS‐CoV‐2 replication in the host reaches its peak in the first week of infection, decreasing rapidly afterwards, while some level of immunity is build up. Yet, the infection seems to follow a distinctive course in some individuals, reactivating after the apparent resolution of symptoms 1‐3 . We report here the first case to be disclosed of a more vigorous COVID‐19 recurrence with SARS‐CoV‐2 RNA redetection and late antibody response, and also the first to address COVID‐19 recurrence in Brazil. This article is protected by copyright. All rights reserved.

BK polyomavirus (BKV) is highly prevalent in the world population. Different reports indicate that BKV subtypes and subgroups present an uneven geographical distribution which might be correlated with human migration. However, there is a lack of data on the BKV subtype distribution in the South American population. The occurrence of BKV subtypes and subgroups detected in 51 kidney transplant recipients in Rio de Janeiro, Brazil is described. According to genetic studies, the population in this region descends mainly from European or African immigrants, with a relatively low genetic background from the Amerindians. By sequencing the VP1 region of BKV, subgroups Ib1 and Ia of subtype I were found in 34 (67%) and 15 (29%), respectively, of samples, while subtype II was present in 2 (4%) of the samples. Subtypes III and IV were not detected. Phylogenetic analysis indicated similarities between Brazilian BKV subgroup Ia and East African lineages; and subgroup Ib-1 with Asian and North American lineages, while subtype II samples were similar to sequences from Japan and the UK. This is the first report that describes distribution of BKV subtypes in South America. The high prevalence of BKV subgroup Ia probably reflects the high proportion of African descendants in this population. On the other hand, the predominance of subgroup Ib-1 and the absence of Ib-2 in an area with a high proportion of European ancestry was unexpected. Further studies in South American populations are needed to provide a better understanding of the epidemiology of BKV in this region.

Despite the frequent detection of MCPyV DNA in NMSC, its possible role in the development of NMSC still needs further investigation.