David Bukbuk

Human Bocaviruses Are Highly Diverse, Dispersed, Recombination Prone, and Prevalent in Enteric Infections

Abstract A new species of parvovirus, tentatively named human bocavirus 4 (HBoV4), was genetically characterized. Among 641 feces samples obtained from children and adults, the most commonly detected bocavirus species were, in descending order, HBoV2, HBoV3, HBoV4, and HBoV1, with an HBoV2 prevalence of 21% and 26% in Nigerian and Tunisian children, respectively. HBoV3 or HBoV4 species were found in 12 of 192 patients with non-polio acute flaccid paralysis in Tunisia and Nigeria and 0 of 96 healthy Tunisian contacts (P= .01). Evidence of extensive recombination at the NP1 and VP1 gene boundary between and within bocavirus species was found. The high degree of genetic diversity seen among the human bocaviruses found in feces specimens, relative to the highly homogeneous HBoV1, suggest that this worldwide-distributed respiratory pathogen may have recently evolved from an enteric bocavirus after acquiring an expanded tropism favoring the respiratory tract. Elucidating the possible role of the newly identified enteric bocaviruses in human diseases, including acute flaccid paralysis and diarrhea, will require further epidemiological studies.

A Novel Picornavirus Associated with Gastroenteritis

ABSTRACT A novel picornavirus genome was sequenced, showing 42.6%, 35.2%, and 44.6% of deduced amino acid identities corresponding to the P1, P2, and P3 regions, respectively, of the Aichi virus. Divergent strains of this new virus, which we named salivirus, were detected in 18 stool samples from Nigeria, Tunisia, Nepal, and the United States. A statistical association was seen between virus shedding and unexplained cases of gastroenteritis in Nepal (P = 0.0056). Viruses with approximately 90% nucleotide similarity, named klassevirus, were also recently reported in three cases of unexplained diarrhea from the United States and Australia and in sewage from Spain, reflecting a global distribution and supporting a pathogenic role for this new group of picornaviruses.

Multiple Independent Emergences of Type 2 Vaccine-Derived Polioviruses during a Large Outbreak in Northern Nigeria

ABSTRACT Since 2005, a large poliomyelitis outbreak associated with type 2 circulating vaccine-derived poliovirus (cVDPV2) has occurred in northern Nigeria, where immunization coverage with trivalent oral poliovirus vaccine (tOPV) has been low. Phylogenetic analysis of P1/capsid region sequences of isolates from each of the 403 cases reported in 2005 to 2011 resolved the outbreak into 23 independent type 2 vaccine-derived poliovirus (VDPV2) emergences, at least 7 of which established circulating lineage groups. Virus from one emergence (lineage group 2005-8; 361 isolates) was estimated to have circulated for over 6 years. The population of the major cVDPV2 lineage group expanded rapidly in early 2009, fell sharply after two tOPV rounds in mid-2009, and gradually expanded again through 2011. The two major determinants of attenuation of the Sabin 2 oral poliovirus vaccine strain (A481 in the 5′-untranslated region [5′-UTR] and VP1-Ile143) had been replaced in all VDPV2 isolates; most A481 5′-UTR replacements occurred by recombination with other enteroviruses. cVDPV2 isolates representing different lineage groups had biological properties indistinguishable from those of wild polioviruses, including efficient growth in neuron-derived HEK293 cells, the capacity to cause paralytic disease in both humans and PVR-Tg21 transgenic mice, loss of the temperature-sensitive phenotype, and the capacity for sustained person-to-person transmission. We estimate from the poliomyelitis case count and the paralytic case-to-infection ratio for type 2 wild poliovirus infections that ∼700,000 cVDPV2 infections have occurred during the outbreak. The detection of multiple concurrent cVDPV2 outbreaks in northern Nigeria highlights the risks of cVDPV emergence accompanying tOPV use at low rates of coverage in developing countries.

Cognitive function in HIV-seropositive Nigerians without AIDS

Studies of cognitive function in individuals with HIV infection who remain relatively asymptomatic have shown widely variable estimates of impairment in different races and countries. Limited data exist on the impact of early asymptomatic HIV infection on cognition in developing nations, and indeed none from Nigeria. Hence, this cross-sectional study sets out to determine whether there are differences between Nigerian asymptomatic HIV-seropositive and HIV-seronegative subjects, and whether such differences: if any, could be explained by the degree of immunosuppression (i.e. CD4 cell count). A selected population of 60 heterosexual asymptomatic treatment-naive HIV-positive subjects were administered the Community Screening Instrument for Dementia (CSI-D) to assess language, memory, registration, attention and calculation, recall, praxis and orientation. HIV positives differed from individually matched control subjects in certain measures of language expression, registration, attention and calculation, orientation to time, motor response and total CSI-D scores. The CD4 cell count of the HIV-seropositive subjects had no significant correlation with the cognitive test scores.

Sabin Vaccine Reversion in the Field: a Comprehensive Analysis of Sabin-Like Poliovirus Isolates in Nigeria.

ABSTRACT To assess the dynamics of genetic reversion of live poliovirus vaccine in humans, we studied molecular evolution in Sabin-like poliovirus isolates from Nigerian acute flaccid paralysis cases obtained from routine surveillance. We employed a novel modeling approach to infer substitution and recombination rates from whole-genome sequences and information about poliovirus infection dynamics and the individual vaccination history. We confirmed observations from a recent vaccine trial that VP1 substitution rates are increased for Sabin-like isolates relative to the rate for the wild type due to increased nonsynonymous substitution rates. We also inferred substitution rates for attenuating nucleotides and confirmed that reversion can occur in days to weeks after vaccination. We combine our observations for Sabin-like virus evolution with the molecular clock for VP1 of circulating wild-type strains to infer that the mean time from the initiating vaccine dose to the earliest detection of circulating vaccine-derived poliovirus (cVDPV) is 300 days for Sabin-like virus type 1, 210 days for Sabin-like virus type 2, and 390 days for Sabin-like virus type 3. Phylogenetic relationships indicated transient local transmission of Sabin-like virus type 3 and, possibly, Sabin-like virus type 1 during periods of low wild polio incidence. Comparison of Sabin-like virus recombinants with known Nigerian vaccine-derived poliovirus recombinants shows that while recombination with non-Sabin enteroviruses is associated with cVDPV, the recombination rates are similar for Sabin isolate-Sabin isolate and Sabin isolate–non-Sabin enterovirus recombination after accounting for the time from dosing to the time of detection. Our study provides a comprehensive picture of the evolutionary dynamics of the oral polio vaccine in the field. IMPORTANCE The global polio eradication effort has completed its 26th year. Despite success in eliminating wild poliovirus from most of the world, polio persists in populations where logistical, social, and political factors have not allowed vaccination programs of sustained high quality. One issue of critical importance is eliminating circulating vaccine-derived polioviruses (cVDPVs) that have properties indistinguishable from those of wild poliovirus and can cause paralytic disease. cVDPV emerges due to the genetic instability of the Sabin viruses used in the oral polio vaccine (OPV) in populations that have low levels of immunity to poliovirus. However, the dynamics responsible are incompletely understood because it has historically been difficult to gather and interpret data about evolution of the Sabin viruses used in OPV in regions where cVDPV has occurred. This study is the first to combine whole-genome sequencing of poliovirus isolates collected during routine surveillance with knowledge about the intrahost dynamics of poliovirus to provide quantitative insight into polio vaccine evolution in the field.

Development and validation of serological assays for viral hemorrhagic fevers and determination of the prevalence of Rift Valley fever in Borno State, Nigeria

Abstract Background Rift Valley fever (RVF) is endemic to the tropical regions of eastern and southern Africa. The seroprevalence of RVF was investigated among the human population in Borno State, Nigeria to determine the occurrence of the disease in the study area in comparison with that of Lassa fever and Crimean-Congo Hemorrhagic fever. Methods Recombinant nucleoprotein (rNP)-based IgG-ELISAs for the detection of serum antibodies against RVF virus (RVFV), Lassa fever virus (LASV), and Crimean-Congo hemorrhagic fever virus (CCHFV) were used to test human sera in Borno State, Nigeria. The presence of neutralizing antibody against the RVFV-glycoprotein-bearing vesicular stomatitis virus pseudotype (RVFVpv) was also determined in the human sera. Results Of the 297 serum samples tested, 42 (14.1%) were positive for the presence of RVFV-IgG and 22 (7.4%) and 7 (2.4%) of the serum samples were positive for antibodies against LASV and CCHFV, respectively. There was a positive correlation between the titers of neutralizing antibodies obtained using RVFVpv and those obtained using the conventional neutralization assay with the attenuated RVFV-MP12 strain. Conclusions The seroprevalence of RVF was significantly higher than that of LASV and CCHF in Borno State, Nigeria. The RVFVpv-based neutralization assay developed in this study has the potential to replace the traditional assays based on live viruses for the diagnosis and seroepidemiological studies of RVF.

Serological and Virological Evidence of Crimean-Congo Haemorrhagic Fever Virus Circulation in the Human Population of Borno State, Northeastern Nigeria.

Background Despite several studies on the seroprevalence of antibodies against Crimean-Congo Haemorrhagic Fever virus (CCHFV) from humans and cattle in Nigeria, detailed investigation looking at IgG and IgM have not been reported. Additionally, there have been no confirmed cases of human CCHFV infection reported from Nigeria. Principal Findings Samples from sera (n = 1189) collected from four Local Government Areas in Borno State (Askira/Uba, Damboa, Jere and Maiduguri) were assessed for the presence of IgG and IgM antibodies. The positivity rates for IgG and IgM were 10.6% and 3.5%, respectively. Additionally, sera from undiagnosed febrile patients (n = 380) were assessed by RT-PCR assay for the presence of CCHFV RNA. One positive sample was characterised by further by next generation sequencing (NGS) resulting in complete S, M and L segment sequences. Conclusions This article provides evidence for the continued exposure of the human population of Nigeria to CCHFV. The genomic analysis provides the first published evidence of a human case of CCHFV in Nigeria and its phylogenetic context.

Development of an efficient entire capsid-coding region amplification method for direct detection of poliovirus from stool extracts

ABSTRACT Laboratory diagnosis has played a critical role in the Global Polio Eradication Initiative since 1988, by isolating and identifying poliovirus (PV) from stool specimens by using cell culture as a highly sensitive system to detect PV. In the present study, we aimed to develop a molecular method to detect PV directly from stool extracts, with a high efficiency comparable to that of cell culture. We developed a method to efficiently amplify the entire capsid coding region of human enteroviruses (EVs) including PV. cDNAs of the entire capsid coding region (3.9 kb) were obtained from as few as 50 copies of PV genomes. PV was detected from the cDNAs with an improved PV-specific real-time reverse transcription-PCR system and nucleotide sequence analysis of the VP1 coding region. For assay validation, we analyzed 84 stool extracts that were positive for PV in cell culture and detected PV genomes from 100% of the extracts (84/84 samples) with this method in combination with a PV-specific extraction method. PV could be detected in 2/4 stool extract samples that were negative for PV in cell culture. In PV-positive samples, EV species C viruses were also detected with high frequency (27% [23/86 samples]). This method would be useful for direct detection of PV from stool extracts without using cell culture.

Neonatal Tetanus Immunity in Nigeria: The Effect of HIV Infection on Serum Levels and Transplacental Transfer of Antibodies

Background. Tetanus toxoid immunisation of pregnant mother has remained the most effective strategy in eliminating neonatal tetanus. Impaired production and/or transplacental transfer of antibodies may affect the effectiveness of this strategy. We studied the effect of maternal HIV infection on serum levels and transplacental transfer of anti-tetanus antibodies. Methods. A total of 162 mother-baby paired serum samples were taken and analysed for anti-tetanus antibody levels using ELISA. Maternal HIV status was also determined by double ELISA technique. Maternal TT vaccination status was also documented. Results. Thirty-eight (23.5%) mothers and 41 (25.3%) babies were seronegative, out of whom 8 mothers were HIV positive and 9 babies were HIV exposed. HIV infected mothers and HIV exposed infants were, respectively, 16.27 times (OR = 16.27, 95% CI = 3.28 to 80.61) and 33.75 times (OR = 33.75, 95% CI = 4.12 to 276.40) more likely to be seronegative for anti-tetanus antibody. Similarly, HIV positive mother-newborn pairs were 7.46 times more likely to have a poor transplacental transfer of tetanus antibodies (OR = 7.46, 95% CI = 1.96 to 28.41). Conclusions. Maternal HIV infection is associated with impaired maternofoetal transfer of anti-tetanus antibodies and seronegativity among mothers and their newborns. Hence, this may hinder efforts to eliminate neonatal tetanus.

Serum cortisol of Sahel goats following rumenotomy with assorted anaesthetics and sutures

Abstract The utmost need for pragmatic combination of surgical sutures and local anaesthetic that would evoke minimal post-surgical stress response and allow uncomplicated healing is essential for successful surgeries. Fifteen Sahel goats were randomly allocated into three groups A, B and C to quantitatively assay (ELISA) serum cortisol profiles following rumenotomy, as markers of surgical stress. Diazepam at 0.2 mg/kg was administered intravenously to groups A and B with subsequent lidocaine HCl and bupivacaine inverted-L block respectively. Group C did not receive any treatment. Chromic catgut (CCG) and polyglycolic acid (PGA) sutures were used for rumen and abdominal muscles closure for groups A and B respectively and nylon for skin closure. Blood samples were taken at post anaesthetic induction (PAI) and post-surgery at 0, 5, 8, 24, 48 and 72 h. The Group A goats expressed serum cortisol that was significantly high 52.76 ± 6.12 ng/mL at 5 h post-surgery. At 8 h post-surgery serum cortisol for both groups A (72.53 ± 3.79 ng/mL) and B (61.59 ± 3.90 ng/mL) were at their peak. Serum cortisol levels compared to the baseline data were significantly different (P < 0.05) at 5, 24, and 48 h for the CCG goats. The serum cortisol levels at 72 h drastically decreased to 20.53 ± 8.74 ng/mL for groups A and 17.59 ± 2.45 ng/mL for group B and were not significantly different (p > 0.05). Cortisol responses unambiguously indicate that diazepam-bupivacaine induce less stress than Diazepam-lidocaine, hence a preferred anesthesia. Moreover, polyglycolic acid sutures are associated with less inflammatory reaction than chromic catgut.