Genetic characterization and diversity of porcine circovirus type 2 in non‐vaccinated South African swine herds

The porcine circovirus type 2 (PCV2) is a swine infectious viral pathogen of great significance in global swine herds. It was recently detected at another Province of South Africa sequel to the first detection of North American‐like strain (PCV2a) at Gauteng about two decades ago, but there is a dearth of information about the genomic features and diversity of the viral strains in circulation within the country and the entire sub‐Saharan Africa region. To date, only one complete genome of the virus from South Africa is available on global data base. This current effort is therefore geared towards the full‐genome characterization of the circulating PCV2 strains in the pigs of Eastern Cape Province. With the use of conventional polymerase chain reaction method, fifteen complete PCV2 genomes were successfully amplified, sequenced and assembled from field samples obtained from non‐vaccinated pigs in the region. Neighbor Joining and Maximum Likelihood phylogenetic analyses of the ORF2 gene and full genomes unanimously showed that most of the assembled genomes (11) belong to genotype PCV2b. Furthermore, three of the characterized sequences formed clade with other reference mutant PCV2b and PCV2b subtype 1C (i.e. PCV2d) strains from the USA, China and South Korea. The last sequence, however, clustered with other reference strains belonging to PCV2 intermediate clade 2 (PCV2‐IM2), recently identified in a global PCV2 strains phylogenetic analysis. This study reports the first complete genome sequences of PCV2b, PCV2d and PCV2‐IM2 in pigs from South Africa, and it gives a possible insight into the genetic characteristics and variability of the viral strains presently in circulation within the country. It further emphasizes the need for more stringent measures in curtailing the introduction and spread of transboundary swine pathogens in the country and entire Southern African region.     

Analysis of the subcellular localization of the proteins Rep, Rep' and Cap of porcine circovirus type 1

Porcine circovirus type 1 (PCV1) encodes two major ORFs. The cap gene comprises the major structural protein of PCV, the rep gene specifies Rep and Rep', which are both essential for initiating the replication of the viral DNA. Rep corresponds to the full-length protein, whereas Rep' is a truncated splice product that is frame-shifted in its C-terminal sequence. In this study, the cellular localization of PCV1-encoded proteins was investigated by immune fluorescence techniques using antibodies against Rep, Rep' and Cap and by expression of viral proteins fused to green and red fluorescence proteins. Rep and Rep' protein co-localized in the nucleus of infected cells as well as in cells transfected with plasmids expressing Rep and Rep' fused to fluorescence proteins, but no signal was seen in the nucleoli. Rep and Rep' carry three potential nuclear localization signals in their identical N-termini, and the contribution of these motifs to nuclear import was experimentally dissected. In contrast to the rep gene products, the localization of the Cap protein varied. While the Cap protein was restricted to the nucleoli in plasmid-transfected cells and was also localized in the nucleoli at an early stage of PCV1 infection, it was seen in the nucleoplasm and the cytoplasm later in infection, suggesting that a shuttling between distinct cellular compartments occurs.     

Neurotoxicity of combination chemotherapy with procarbazine,CCNU and vincristine (PCV) for recurrent glioma

In cerebral glioma combination chemotherapy with procabazine, CCNU and vincristine (PCV) is used as adjuvant therapy in cases of recurrence. Standard PCV is usually well tolerated, but intensive PCV (CCNU 130 mg/m² on day 1, procarbazine 75 mg/m² on day 8–21, vincristine 1.4 mg/m² on day 8 and 29; 6 courses every 6 weeks) is less well tolerated. We observed central neurotoxic side effects (focal neurological deficit, cognitive disturbances, slowing of EEG background activity, atrophy on cerebral MR) in combination with hematological and hepatic toxicity in four of 26 PCV treated patients with recurrent glioma. Prolonged myelosuppression and/or ongoing (partial reversible in two patients) neurological deficit still influence daily life in three of four patients months after discontinuation of chemotherapy. Despite the fact that all four patients used anticonvulsants and have been treated with radiotherapy in the past, we have the strong impression that central neurotoxic side effects are related to intensive PCV therapy. We advocate to use the standard PCV regimen in patients with recurrent glioma, because of this potential toxicity and the lack of evidence that intensive PCV leads to better tumor control than standard PCV in cerebral glioma.     

Lack of effectiveness of 13-valent pneumococcal conjugate vaccination against pneumococcal carriage density in Papua New Guinean infants

BackgroundPapua New Guinea (PNG) introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in 2014, with administration at 1, 2, and 3 months of age. PCV13 has reduced or eliminated carriage of vaccine types in populations with low pneumococcal carriage prevalence, carriage density and serotype diversity. This study investigated PCV13 impact on serotype-specific pneumococcal carriage prevalence, density, and serotype diversity in PNG infants, who have some of the highest reported rates of pneumococcal carriage and disease in the world.MethodsNasopharyngeal swabs were collected at 1, 4 and 9 months of age from PCV13-vaccinated infants (n = 57) and age-/season-matched, unvaccinated infants (at approximately 1 month, n = 53; 4 months, n = 57; 9 months, n = 52). Serotype-specific pneumococcal carriage density and antimicrobial resistance genes were identified by qPCR and microarray.ResultsPneumococci were present in 89% of swabs, with 60 different serotypes and four non-encapsulated variants detected. Multiple serotype carriage was common (47% of swabs). Vaccine type carriage prevalence was similar between PCV13-vaccinated and unvaccinated infants at 4 and 9 months of age. The prevalence of non-vaccine type carriage was also similar between cohorts, with non-vaccine types present in three-quarters of samples (from both vaccinated and unvaccinated infants) by 4 months of age. The median pneumococcal carriage density was high and similar at each age group (~7.0 log₁₀ genome equivalents/mL). PCV13 had no effect on overall pneumococcal carriage density, vaccine type density, non-vaccine type density, or the prevalence of antimicrobial resistance genes.ConclusionPNG infants experience dense and diverse pneumococcal colonisation with concurrent serotypes from 1 month of age. PCV13 had no impact on pneumococcal carriage density, even for vaccine serotypes. The low prevalence of vaccine serotypes, high pneumococcal carriage density and abundance of non-vaccine serotypes likely contribute to the lack of PCV13 impact on carriage in PNG infants. Indirect effects of the infant PCV programs are likely to be limited in PNG. Alternative vaccines with broader coverage should be considered.     

First report of wild boar susceptibility to Porcine circovirus type 3: High prevalence in the Colli Euganei Regional Park (Italy) in the absence of clinical signs

The genus Circovirus includes one of the most relevant infectious agents affecting domestic pigs, Porcine circovirus type 2 (PCV ‐2). The wild boar susceptibility to this pathogen has also been demonstrated although the actual epidemiological role of wild populations is still debated. In recent times, a new circovirus, Porcine circovirus type 3 (PCV ‐3), has been discovered and reported in the presence of several clinical conditions. However, no information is currently available about PCV ‐3 circulation and prevalence in wild boar. To fill this gap, 187 wild boar serum samples were collected in the Colli Euganei Regional Park (Northern Italy) and screened for PCV ‐3, demonstrating a high viral prevalence (approximately 30%). No gender differences were demonstrated while a lower infection prevalence was observed in animals younger than 12 months compared to older ones, differently from what described in commercial pigs. Almost all sampled animals were in good health conditions and no association was proven between PCV ‐3 status and clinical syndromes in wild animals. The genetic characterization of selected strains enlightened a relevant variability and the absence of closely related strains originating from domestic pigs. Therefore, the observed scenario is suggestive of multiple introductions from other wild or domestic swine populations followed by prolonged circulation and independent evolution. Worldwide, this study reports for the first time the high susceptibility of the wild boar to PCV ‐3 infection. The high prevalence and the absence of association with clinical signs support the marginal role of this virus in the wild boar population ecology. However, its epidemiological role as reservoir endangering commercial swine cannot be excluded and will require further investigations.     

Translating vaccine policy into action: A report from the Bill & Melinda Gates Foundation Consultation on the prevention of maternal and early infant influenza in resource-limited settings

Immunization of pregnant women against influenza is a promising strategy to protect the mother, fetus, and young infant from influenza-related diseases. The burden of influenza during pregnancy, the vaccine immunogenicity during this period, and the robust influenza vaccine safety database underpin recommendations that all pregnant women receive the vaccine to decrease complications of influenza disease during their pregnancies. Recent data also support maternal immunization for the additional purpose of preventing disease in the infant during the first six months of life.     

The development of 13-valent pneumococcal conjugate vaccine and its possible use in adults

Introduction: Worldwide, Streptococcus pneumoniae causes significant morbidity and mortality. The 23-valent pneumococcal polysaccharide vaccine (PPSV23) has been recommended for use in persons aged 65 years and over and in adults with certain chronic medical conditions. Pneumococcal conjugate vaccines (PCVs) have been developed for use in infants and children aged less than 5 years, and are being studied for use in adult populations.

Areas covered: The different types of pneumococcal vaccines are discussed. Studies comparing PPSV23 and PCVs, as well as the results of the widespread use of 7-valent PCV are covered. The possible extension of the use of 13-valent PCV to adults, particularly to vulnerable populations, is discussed. The MEDLINE database was used to identify relevant studies from literature published in English between January 1977 and January 2011. All studies of adults aged over 18 years were considered for the review.

Expert opinion: Elderly individuals and adults with chronic medical conditions who are at increased risk for pneumococcal disease would benefit from more effective prevention than is provided by the currently recommended PPSV23.     

Early impact of PCV7/PCV13 sequential introduction to the national pediatric immunization plan,on adult invasive pneumococcal disease: A nationwide surveillance study

BackgroundPCV7 was introduced as a universal childhood vaccination in Israel on July 2009 and was gradually replaced by PCV13 from November 2010. We report data on adult invasive pneumococcal disease (IPD), two years post PCV13 implementation.MethodsAn ongoing nationwide active surveillance (all 27 laboratories performing blood/CSF cultures nationwide), initiated in 2009, providing all blood/CSF Streptococcus pneumoniae isolated from persons ≥18 years. Capture-recapture method assured reporting of >95% cases. All isolates were serotyped in one central laboratory. Medical history and outcomes were recorded in ∼90%.ResultsOf 1809 IPD episodes, S. pneumoniae was isolated from the blood in 95% and most cases had pneumonia. Predisposing comorbidities were present in >70%. During the four study years, overall IPD incidence decreased from 9.2 to 7.2/100,000, incidence of pneumonia and particularly severe pneumonia cases decreased significantly from 6.6 to 4.7/100,000, (p = 0.029). Vaccine type (VT7/VT13) serotypes decreased by 70%/57% within 4 years. This was accompanied by a 52% increase in non-VT13 strains. These changes were most apparent in winter. PCV impact was most pronounced in younger adults (39% decrease in overall IPD with only a non-significant increase in non-VT13 cases) while in those >65 years a non-significant decrease in overall IPD was observed with a 64% increase in non-VT13 cases. Non-VT13 serotypes that increased significantly were 12F, 15A 10A and 6 C. A continuous reduction in isolates with penicillin MIC > 0.06 μg/ml was observed (26% to 11%, p < 0.001).ConclusionsFour years after PCV7 and 2.5 years after PCV13 universal implementation in children, incidence of adult IPD caused by VT7 and VT13 decreased in all ages, mainly in younger adults. Despite increase in non-VT13 IPD, overall IPD decreased. Additional follow-up is needed to determine the long-term impact of PCV13.