Rubella vaccine-induced granulomas are a novel phenotype with incomplete penetrance of genetic defects in cytotoxicity.

BACKGROUND: Rubella virus-induced granulomas have been described in patients with various inborn errors of immunity. Most defects impair T-cell immunity, suggesting a critical role of T cells in rubella elimination. However, the molecular mechanism of virus control remains elusive. OBJECTIVE: This study sought to understand the defective effector mechanism allowing rubella vaccine virus persistence in granulomas. METHODS: Starting from an index case with Griscelli syndrome type 2 and rubella skin granulomas, this study combined an international survey with a literature search to identify patients with cytotoxicity defects and granuloma. The investigators performed rubella virus immunohistochemistry and PCR and T-cell migration assays. RESULTS: This study identified 21 patients with various genetically confirmed cytotoxicity defects, who presented with skin and visceral granulomas. Rubella virus was demonstrated in all 12 accessible biopsies. Granuloma onset was typically before 2 years of age and lesions persisted from months to years. Granulomas were particularly frequent in MUNC13-4 and RAB27A deficiency, where 50% of patients at risk were affected. Although these proteins have also been implicated in lymphocyte migration, 3-dimensional migration assays revealed no evidence of impaired migration of patient T cells. Notably, patients showed no evidence of reduced control of concomitantly given measles, mumps, or varicella live-attenuated vaccine or severe infections with other viruses. CONCLUSIONS: This study identified lymphocyte cytotoxicity as a key effector mechanism for control of rubella vaccine virus, without evidence for its need in control of live measles, mumps, or varicella vaccines. Rubella vaccine-induced granulomas are a novel phenotype with incomplete penetrance of genetic disorders of cytotoxicity.

Transcription-associated mutational pressure in the Parvovirus B19 genome: Reactivated genomes contribute to the variability of viral populations.

In this study we used non-overlapping parts of the two long open reading frames coding for nonstructural (NS) and capsid (VP) proteins of all available sequences of the Parvovirus B19 subgenotype 1a genome and found out that the rates of A to G, C to T and A to T mutations are higher in the first long reading frame (NS) of the virus than in the second one (VP). This difference in mutational pressure directions for two parts of the same viral genome can be explained by the fact of transcription of just the first long reading frame during the lifelong latency in nonerythroid cells. Adenine deamination (producing A to G and A to T mutations) and cytosine deamination (producing C to T mutations) occur more frequently in transcriptional bubbles formed by DNA "plus" strand of the first open reading frame. These mutations can be inherited only in case of reactivation of the infectious virus due to the help of Adenovirus that allows latent Parvovirus B19 to start transcription of the second reading frame and then to replicate its genome by the rolling circle mechanism using the specific origin. Results of this study provide evidence that the genomes reactivated from latency make significant contributions to the variability of Parvovirus B19.

Etiology of maculopapular rash in measles and rubella suspected patients from Belarus.

As a result of successful implementation of the measles/rubella elimination program, the etiology of more and more double negative cases remains elusive. The present study determined the role of different viruses as causative agents in measles or rubella suspected cases in Belarus. A total of 856 sera sent to the WHO National Laboratory between 2009 and 2011 were tested for specific IgM antibodies to measles virus (MV), rubella virus (RV) and human parvovirus B19 (B19V). The negatives were further investigated for antibodies to enterovirus (EV) and adenovirus (AdV). Children of up to 3 years were tested for IgM antibodies to human herpesvirus 6 (HHV6). A viral etiology was identified in 451 (52.7%) cases, with 6.1% of the samples being positive for MV; 2.6% for RV; 26.2% for B19V; 9.7% for EV; 4.6% for AdV; and 3.6% for HHV6. Almost all measles and rubella cases occurred during limited outbreaks in 2011 and nearly all patients were at least 15 years old. B19V, EV and AdV infections were prevalent both in children and adults and were found throughout the 3 years. B19V occurred mainly in 3-10 years old children and 20-29 years old adults. EV infection was most common in children up to 6 years of age and AdV was confirmed mainly in 3-6 years old children. HHV6 infection was mostly detected in 6-11 months old infants. Laboratory investigation of measles/rubella suspected cases also for B19V, EV, AdV and HHV6 allows diagnosing more than half of all cases, thus strengthening rash/fever disease surveillance in Belarus.

Phylogenetic analysis of rubella viruses involved in congenital rubella infections in France between 1995 and 2009.

Rubella is an acute infectious disease that normally has a mild clinical course. However, infections during pregnancy, especially before week 12 of gestation (WG), can cause severe birth defects known as congenital rubella syndrome (CRS). The aim of this study was to perform genotyping and molecular characterization of rubella viruses involved in congenital infections in France over the past 15 years (1995 to 2009). Amniotic fluid (AF) specimens (n = 80) from pregnant women with congenital rubella infections (CRI) before week 20 of gestation, and a few other samples available from children/newborns with CRS (n = 26), were analyzed. The coding region of the rubella virus E1 gene was amplified directly from clinical specimens by reverse transcriptase PCR, and the resulting DNA fragments were sequenced. Sequences were assigned to genotypes by phylogenetic analysis with rubella virus reference sequences. Sufficient E1 gene sequences were obtained from 56 cases. Phylogenetic analysis of the sequences showed that at least five different genotypes (1E, 1G, 1B, 2B, and 1h) were present in France and were involved in congenital infections, with a strong predominance of genotype 1E (87%). This is one of the very few comprehensive studies of rubella viruses involved in CRI. The results indicated that over the past 15 years, multiple introductions of the dominant genotype E caused most of the CRI cases in France. A few sporadic cases were due to other genotypes (1B, 1G, 1h, 2B).

Co-circulation of multiple rubella virus strains in Belarus forming novel genetic groups within clade 1.

Although the WHO recommends a comprehensive genetic characterization, little is known about circulating strains and genotypes of rubella virus (RUBV) for many European countries. Studies investigating the genetic diversity of a sizeable number of strains from a certain location are rare. This study presents the first molecular characterization of isolates from Belarus. Throat swab and urine samples were collected between 2004 and 2005 from patients presenting in two infectious disease hospitals and three outpatient clinics in and around Minsk. In total, 14 isolates were obtained from this clinical material. Phylogenetic analysis of the E1 gene sequence of these isolates showed that three distinct groups of RUBV strains co-circulated. One group of isolates was assigned to genotype 1E, whereas the other two did not group with any of the recognized genotypes but grouped with a strain belonging to the provisional genotype 1g. Detailed analysis showed that the group comprising 1g strains also contained sequences formerly attributed to genotype 1B and could be divided into four subgroups, one of which might represent a putative novel provisional genotype of clade 1. These findings show that three distinct strains with limited variability are present in Belarus, suggesting independent introductory events. As there currently seem to be misattributions of strains to genotypes and unclear phylogenetic relationships, criteria for genotyping of RUBV should be clarified further.