Awareness, attitudes, and practices on meningococcal serogroup B vaccination in the United States among parents of older adolescents and among young adults.

OBJECTIVE: Meningococcal serogroup B (MenB) vaccination is recommended by the Advisory Committee on Immunization Practices (ACIP) for adolescents and young adults 16-23-years-old under shared clinical decision-making (SCDM). However, MenB vaccination coverage in this population remains low in the United States (US). We investigated the awareness, attitudes, and practices regarding MenB disease and vaccination among parents of 16-18-year-old older adolescents and among 19-23-year-old young adults. METHODS: An online survey was conducted in September-October 2022 among parents of older adolescents and among young adults recruited from a US-based patient panel. RESULTS: There were 606 total participants, including parents of MenB-vaccinated (n = 151) and non-vaccinated (n = 154) adolescents, and also MenB-vaccinated (n = 150) and non-vaccinated (n = 151) young adults. Non-vaccinated cohorts reported low awareness of MenB disease (58.3-67.5%) and vaccination (49.7-61.0%), though awareness was higher among non-vaccinated parents. However, all cohorts reported high interest in learning more about MenB disease and vaccination. Vaccinated cohorts relied on primary care providers (PCPs) to initiate MenB vaccination conversation and had a low awareness of SCDM at 35.1-45.3%, though those aware of SCDM were more likely to participate in decision-making. Barriers to MenB vaccination included lack of PCP recommendation, vaccine side effects, and uncertainty about vaccination need. CONCLUSIONS: There are gaps in awareness of MenB disease, vaccination, and SCDM among parents and patients in the US, resulting in missed opportunities for discussing and administering MenB vaccination. Targeted education on MenB and vaccination recommendations may increase these opportunities and improve MenB vaccination awareness and initiation.

MenB disease, a type of meningitis, is a serious and life-threatening illness. The US Centers for Disease Control and Prevention (CDC) recommends that 16­23-year-olds get a MenB vaccine after talking with their healthcare provider and deciding it is the right choice. As of 2021, only about 3 in 10 17-year-olds had received a MenB vaccine. In this study, we used an online survey to learn about parents of older teens' (16­18-years-old) and young adults' (19­23-years-old) awareness, thoughts, and practices related to meningitis and the MenB vaccine. Parents of non-vaccinated teens, and non-vaccinated young adults, had a lower awareness of the causes, risks, and symptoms of meningitis, and the MenB vaccine. In addition, most parents thought the impact of meningitis would be severe, compared with young adults who thought it would be less severe. Most participants were also not aware of their role in deciding if they or their child should be vaccinated against MenB. However, most showed a high interest in learning more about meningitis and the MenB vaccine. We also found that most teens and young adults who did receive the MenB vaccine received it right after talking about it with their healthcare provider. These findings show a clear opportunity to address gaps in awareness and thoughts about meningitis and MenB vaccination. Providing education and resources to parents, young adults, and healthcare providers could create more opportunities to discuss MenB vaccination and lead to more teens and young adults accessing vaccination and being protected against meningitis.

Use of expanded Neisseria meningitidis serogroup B panels with the serum bactericidal antibody assay for the evaluation of meningococcal B vaccine effectiveness.

INTRODUCTION: Neisseria meningitidis serogroup B (NmB) antigens are inherently diverse with variable expression among strains. Prediction of meningococcal B (MenB) vaccine effectiveness therefore requires an assay suitable for use against large panels of epidemiologically representative disease-causing NmB strains. Traditional serum bactericidal antibody assay using exogenous human complement (hSBA) is limited to the quantification of MenB vaccine immunogenicity on a small number of indicator strains. AREAS COVERED: Additional and complementary methods for assessing strain coverage developed previously include the Meningococcal Antigen Typing System (MATS), Meningococcal Antigen Surface Expression (MEASURE) assay, and genotyping approaches, but these do not estimate vaccine effectiveness. We provide a narrative review of these methods, highlighting a more recent approach involving the hSBA assay in conjunction with expanded NmB strain panels: hSBA assay using endogenous complement in each vaccinated person's serum (enc-hSBA) against a 110-strain NmB panel and the traditional hSBA assay against 14 (4 + 10) NmB strains. EXPERT OPINION: The enc-hSBA is a highly standardized, robust method that can be used in clinical trials to measure the immunological effectiveness of MenB vaccines under conditions that mimic real-world settings as closely as possible, through the use of endogenous complement and a diverse, epidemiologically representative panel of NmB strains.

Meningococcal disease refers to illnesses caused by the bacterium Neisseria meningitidis (meningococcus), including infections of the brain lining and spinal cord (meningitis) and bloodstream (septicemia). It is rare but often severe and can be deadly. Invasive meningococcal disease can be prevented through vaccination. Nearly all cases are caused by six serogroups (types) of meningococci, including meningococcal serogroup B. Vaccines are available against meningococcal serogroup B but, because of the uncommonness of the disease, standard clinical trials could not be performed to prove these vaccines are effective. Instead, an indirect measure, called the 'hSBA assay' (serum bactericidal antibody assay using human complement), is used to measure the ability of vaccines to provide protection against specific N. meningitidis strains that have antigens (substances that cause the immune system to react) sharing characteristics with components of the vaccines. However, meningococcal serogroup B strains are diverse in the genetic composition and expression of vaccine antigens. Hence, a large number of N. meningitidis serogroup B strains would have to be tested to make sure that the vaccine is effective against these strains. This is not feasible using the traditional hSBA assay, which requires a human complement (a protein system, which is part of the immune system) that has not come from the vaccinated person and is difficult and time-consuming to source. Recently, an alternative hSBA assay was developed that uses the complement present in each vaccinated person's blood (endogenous complement) and which overcomes these challenges. By allowing testing against a broad panel of N. meningitidis serogroup B strains, this new assay may enable a more accurate estimation of the effectiveness of vaccines against serogroup B meningococci.

In vitro replication phenotype of a novel (-1G) hepatitis B virus variant associated with HIV co-infection.

The -1G mutant HBV is more prevalent in individuals co-infected with HIV/HBV than in individuals infected with HBV alone and in some cases is the dominant virus in circulation. This mutant is created by the deletion of a dGMP (-1G) from the guanine rich homopolymer sequence located at nts 2,085-2,090 (numbering from EcoRI site as position 1) in the HBV core gene. This deletion causes a frameshift generating a premature stop codon at (64) Asn in the HBV core gene (codon 93 in the precore gene), that truncates the precore protein, precursor of the secreted hepatitis B "e" antigen (HBeAg), and the core protein which forms the viral nucleocapsid. However, the replication phenotype of the -1G mutant HBV is unknown. An in vitro cell culture model in which hepatoma cells were transiently transfected with infectious cDNAs was used to show that the -1G mutant HBV is incapable of autonomous replication and, as expected, replication was restored to wild-type (wt) levels by supplying HBV core protein in trans. Although the -1G mutation had no deleterious effect on intracellular HBV-DNA levels, high levels of -1G mutant HBV relative to wt HBV reduced virus secretion and HBeAg secretion relative to empty vector controls. Importantly, the -1G mutant HBV also caused intracellular retention of truncated precore protein in the endoplasmic reticulum (ER) and Golgi apparatus. Together, these effects may be contributing to the increased pathology observed in the setting of HIV/HBV co-infection.

Public health perspective of a pentavalent meningococcal vaccine combining antigens of MenACWY-CRM and 4CMenB.

OBJECTIVES: Invasive meningococcal disease (IMD) is a life-threatening disease that can rapidly progress to death or leave survivors with severe, life-long sequelae. Five meningococcal serogroups (A, B, C, W and Y) account for nearly all IMD. Meningococcal serogroup distribution fluctuates over time across the world and age groups. Here, we consider the potential public health impact of a pentavalent MenABCWY vaccine developed to help further control meningococcal disease and improve immunisation rates. RESULTS: The GSK MenABCWY vaccine combines the antigenic components of MenACWY-CRM (Menveo®) and 4CMenB (Bexsero®), building on a wide body of clinical experience and real-world evidence. Both approved vaccines have acceptable safety profiles, demonstrate immunogenicity, and are broadly used, including in national immunisation programmes in several countries. Since the advent of quadrivalent vaccines, public health in relation to IMD has improved, with a decline in the overall incidence of IMD and an increase in vaccine coverage. CONCLUSION: A pentavalent MenABCWY has the potential to provide further public health benefits through practical, broad IMD protection programmes encompassing serogroups A, B, C, W and Y, and is currently in late-stage development.

Down-regulation of intra-hepatic T-cell signaling associated with GB virus C in a HCV/HIV co-infected group with reduced liver disease.

BACKGROUND & AIMS: Studies have shown that GB virus C (GBV-C) infection leads to reduced liver disease in hepatitis C virus (HCV)/human immunodeficiency virus (HIV) co-infection. Considering that the underlying mechanism(s) are unknown, we aim to identify differential gene and protein expression associated with GBV-C in HCV/HIV co-infection that may be responsible for reduced liver disease. METHODS: Liver, peripheral blood mononuclear cells (PBMCs), and plasma samples were collected from 43 HCV/HIV patients. Plasma was tested for GBV-C RNA by RT-PCR with NS5B gene primers. A microarray was performed on the liver and RT-qPCRs on the liver/PBMC samples. Hepatic protein expression was measured by immunohistochemistry. RESULTS: Sixteen out of 43 patients had GBV-C RNA. GBV-C was associated with reduced hepatic fibrosis (p=0.005) and inflammation (p=0.007). The microarray analysis of the liver samples (n=10) showed down-regulation of genes critical to intra-hepatic T-cell signaling associated with GBV-C. Quantitative RT-PCR of the liver samples (n=13) confirmed the down-regulation of lymphocyte-specific protein tyrosine kinase (LCK) (p=0.02) and docking protein 2 (DOK2) (p=0.04). No differences in the expression levels of these genes were observed in PBMCs (n=22) according to the GBV-C status. The hepatic expression of the LCK protein, measured by immunohistochemistry (n=36), was decreased in CD3-positive T-cells within portal tracts associated with GBV-C (p=0.003). This remained significant in multivariate analysis controlling for hepatic fibrosis and inflammation (p=0.027). No differences were observed in plasma cytokine concentrations (n=25) or ex-vivo peripheral T-cell responses (n=13) versus GBV-C status. CONCLUSIONS: GBV-C infection is associated with down-regulation of critical genes involved in intra-hepatic T-cell signaling in HCV/HIV co-infection. This may be relevant to the pathogenesis of reduced HCV-related liver disease in HIV co-infection.

Expert opinion on the way forward for improving maternal influenza vaccination in India.

INTRODUCTION: : Rates of maternal vaccination against influenza are extremely low in India. An expert panel of obstetric-gynecologists and pediatricians met to develop consensus-based recommendations for improving awareness of the benefits of influenza vaccination during pregnancy in India. AREAS COVERED: : The group discussed experiences of influenza infection in pregnancy and infancy before focusing on maternal vaccination practices in India, including the degree of communication between obstetric-gynecologists and pediatricians and opinions on optimal timing for vaccination. The impact of inconsistent vaccine prescription practices by healthcare providers was discussed, as well as current clinical recommendations on maternal influenza vaccination. EXPERT OPINION: : Although clinical evidence demonstrates the benefit of maternal influenza vaccination in any trimester, influenza vaccination is not widely accepted in India as an integral part of antenatal care. There is a lack of familiarity among obstetricians of clinical guidelines on maternal influenza vaccination. This can be addressed with an education campaign targeting obstetricians and other providers of maternal healthcare. With variable influenza seasons between regions in India, common vaccine stock shortages, and data suggesting influenza vaccination is feasible anytime in pregnancy, all opportunities to offer vaccination to this high-risk group for severe influenza disease should be considered.

Vaccinating pregnant women against influenza needs to be a priority for all countries: An expert commentary.

BACKGROUND: In 2012, the World Health Organization recommended influenza vaccination for all pregnant women worldwide and the prioritisation of pregnant women in national influenza vaccination programmes. Nevertheless, vaccination rates in pregnant women often remain much lower than national targets. OBJECTIVES: To assess the benefits and risks associated with influenza infection and vaccination during pregnancy, and to consider obstacles that work against influenza vaccine uptake during pregnancy. RESULTS: There is strong evidence that maternal and foetal outcomes can be compromised if women develop influenza infections during pregnancy. Influenza vaccines have been administered to millions of pregnant women and have demonstrated benefits in terms of disease prevention in mothers and their infants. There is a consensus amongst several recommending authorities that influenza vaccines may be safely administered during all stages of pregnancy. Healthcare professionals are recognised as the most important influencers of vaccine uptake, being well placed to recommend vaccination and directly address safety concerns. CONCLUSIONS: Despite data supporting the value of influenza vaccination during pregnancy, vaccine uptake remains low globally. Low uptake appears to be largely due to ineffective communication with pregnant women about the risks and benefits of influenza vaccination. A graphical abstract is available online.

Health economic assessment of a rabies pre-exposure prophylaxis program compared with post-exposure prophylaxis alone in high-risk age groups in the Philippines.

OBJECTIVES: Once symptoms appear, rabies is almost always fatal and accounts for 200-300 deaths annually in the Philippines. Available rabies vaccines can be administered either in pre- exposure prophylaxis (PrEP) or post-exposure prophylaxis (PEP). After exposure, PrEP-immunized individuals require fewer doses of PEP and no rabies immunoglobulin. METHODS: A static decision-tree model was developed to assess cost-effectiveness of a PrEP+PEP program vs PEP alone. Philippines-specific data for people seeking medical advice at the Research Institute for Tropical Medicine between July 2015 and June 2016 were used in the model, together with data from published literature. RESULTS: Over a 20-year period, in a cohort of 1 million 5-year-old children in the Philippines, PrEP+PEP was expected to prevent 297 deaths compared with PEP alone. From both payer and societal perspectives, the resulting incremental cost-effectiveness ratios were 36 035 (US$759; 2016 US$ conversion) and 18 663 (US$393) Philippine Pesos (PHP) - quality-adjusted life-years gained - respectively, which are both below the willingness-to-pay threshold of PHP140 255 (US$2 953). CONCLUSION: These data suggest that a universal PrEP program targeting 5-year-olds would be cost-effective in the Philippines.

Defective hepatitis B virus DNA is not associated with disease status but is reduced by polymerase mutations associated with drug resistance.

UNLABELLED: Defective hepatitis B virus DNA (dDNA) is reverse-transcribed from spliced hepatitis B virus (HBV) pregenomic messenger RNA (pgRNA) and has been identified in patients with chronic HBV (CH-B). The major 2.2-kb spliced pgRNA encodes a novel HBV gene product, the hepatitis B splice protein (HBSP) via a deletion and frame shift within the polymerase. Although spliced RNA and HBSP expression have been associated with increased HBV DNA levels and liver fibrosis, the role of dDNA in HBV-associated disease is largely undefined. Our aims were to (1) compare the relative proportions of dDNA (% dDNA) in a range of HBV-infected serum samples, including patients with human immunodeficiency virus (HIV)/HBV coinfection and HBV-monoinfected persons with differing severities of liver disease, and (2) determine the effect of mutations associated with drug resistance on defective DNA production. Defective DNA was detected in 90% of persons with CH-B. There was no significant difference in the relative abundance of dDNA between the monoinfected and HIV/HBV-coinfected groups. We also found no association between the % dDNA and alanine aminotransferase, hepatitis B e antigen status, HBV DNA levels, fibrosis levels, compensated or decompensated liver cirrhosis, genotype, or drug treatment. However, the % dDNA was significantly lower in individuals infected with lamivudine-resistant (LMV-R) HBV compared with wild-type HBV (P < 0.0001), indicating that antiviral drug resistance alters the balance between defective and genomic length DNA in circulation. Experiments in vitro using HBV encoding LMV-R mutations confirmed these results. CONCLUSION: Our results identified no association between dDNA and parameters associated with disease status and suggested that the relative abundance of dDNA is largely dependent on the integrity of the HBV polymerase and is unrelated to the severity of liver disease.

Post-exposure prophylaxis (PEP) for rabies with purified chick embryo cell vaccine: a systematic literature review and meta-analysis.

INTRODUCTION: Fifteen million people each year receive post-exposure prophylaxis (PEP) to prevent rabies, yet the disease remains neglected and highly under-reported. AREAS COVERED: In this systematic literature review, we assessed the immunogenicity, efficacy, and safety of a purified chick embryo cell-culture rabies vaccine (PCECV) for PEP against rabies by intramuscular (IM) or intradermal (ID) administration. We performed meta-analyses to compare immunogenicity according to the route of vaccine administration, study population, and PEP regimen, such as number of doses, and concomitant rabies immunoglobulin. EXPERT COMMENTARY: There were 54 estimates of immune responses to vaccination, which showed that in the overall population, after starting PEP with PCECV by the IM or ID route (≥2.5 IU per dose), almost all individuals had rabies virus neutralizing antibody (RVNA) titers above the World Health Organization (WHO) recommended serological threshold for an adequate immune response to vaccination (RVNA ≥0.5 IU/ml by day 14). In the overall population, PCECV had an acceptable safety profile. However, given that there are 59,000 human rabies deaths reported annually, the challenge is to improve access to PCECV for PEP against human rabies.

Heterogeneity of Rabies Vaccination Recommendations across Asia.

Asian countries bear the greatest burden of the disease, with a majority (59%) of rabies-related deaths occurring in Asia. In order to promote best practices, we summarized national human vaccination guidelines across this region, to highlight differences and similarities and to discuss the aspects that would benefit from updates. National management guidelines for rabies were retrieved from various sources to extract information on rabies pre- and post-exposure prophylaxis (PrEP, and PEP), booster vaccination, and route of administration. Rabies guidelines recommendations for wound management and PrEP across Asia are broadly aligned to the World Health Organization (WHO) guidelines. For PEP, the 5-dose Essen, and the 4-dose Zagreb are the regimens of choice for intramuscular (IM), and the Thai Red Cross regimen for intradermal (ID), administration. Several national guidelines have yet to endorse ID vaccine administration. Most guidelines recommend rabies immunoglobulin in category III exposures. Booster recommendations are not included in all guidelines, with limited clarity on booster requirement across the spectrum of risk of rabies exposure. In conclusion, national recommendations across Asian countries differ and while some guidelines are closely aligned to the WHO recommendations, resource-saving ID administration and use of rational abbreviated schedules have yet to be endorsed.

Comparison of the immunogenicity and safety of the purified chick embryo cell rabies vaccine manufactured in India and Germany: A randomized, single blind, multicentre, phase IV clinical study.

This phase IV, single blind study assessed the immunogenicity and safety of India-manufactured purified chick embryo cell rabies vaccine (PCECV), compared with a German-manufactured batch obtained by the same production process. A total of 340 participants enrolled at 2 study sites in India were randomized (1:1:1:1) in 4 groups to receive a 5-dose Essen regimen with either 1 of the 3 Indian batches (PCECV-I) or the German batch (PCECV-G), administered on Days (D) 0, 3, 7, 14 and 30. The lot-to-lot consistency of PCECV-I batches in terms of induced immune response at D14 was demonstrated. The immune response elicited by PCECV-I was shown to be non-inferior to that induced by PCECV-G, as the lower limit of the 95% confidence interval for the ratio (PCECV-I/PCECV-G) of rabies virus neutralising antibody (RVNA) geometric mean concentrations was higher than 0.5 at D14. At least 96% of participants developed adequate RVNA concentrations (≥ 0.5 IU/mL) by D14 and all achieved RVNA concentrations ≥ 0.5 IU/mL by D90. RVNA levels were comparable across all groups throughout the entire study. Solicited local and general symptoms had a similar incidence in all groups. Unsolicited adverse events (AEs) were reported by 11% of participants. Only 1 serious AE (leg fracture) was reported and was not related to vaccination. No deaths and no rabies cases were recorded during the 90 days of observation. The study showed that the 3 PCECV-I and the PCECV-G batches induced a similar immune response and had a comparable safety profile when administered according to a 5-dose schedule.

Vaccine provision: Delivering sustained & widespread use.

The administration of a vaccine to a recipient is the final step in a development and production process that may have begun several decades earlier. Here we describe the scale and complexity of the processes that brings a candidate vaccine through clinical development to the recipient. These challenges include ensuring vaccine quality (between 100 and 500 different Quality Control tests are performed during production to continually assess safety, potency and purity); making decisions about optimal vaccine presentation (pre-filled syringes versus multi-dose vials) that affect capacity and supply; and the importance of maintaining the vaccine cold chain (most vaccines have stringent storage temperature requirements necessary to maintain activity and potency). The ultimate aim is to make sure that an immunogenic product matching the required specifications reaches the recipient. The process from concept to licensure takes 10-30years. Vaccine licensure is based on a file submitted to regulatory agencies which contains the comprehensive compilation of chemistry, manufacturing information, assay procedures, preclinical and clinical trial results, and proposals for post-licensure effectiveness and safety data collection. Expedited development and licensure pathways may be sought in emergency settings: e.g., the 2009 H1N1 influenza pandemic, the 2014 West African Ebola outbreak and meningococcal serogroup B meningitis outbreaks in the United States and New Zealand. Vaccines vary in the complexity of their manufacturing process. Influenza vaccines are particularly challenging to produce and delays in manufacturing may occur, leading to vaccine shortages during the influenza season. Shortages can be difficult to resolve due to long manufacturing lead times and stringent, but variable, local regulations. New technologies are driving the development of new vaccines with simplified manufacturing requirements and with quality specifications that can be confirmed with fewer tests. These technologies could have far-reaching effects on supply, cost of goods, and on response timing to a medical need until product availability.

Vaccine strategies: Optimising outcomes.

Successful immunisation programmes generally result from high vaccine effectiveness and adequate uptake of vaccines. In the development of new vaccination strategies, the structure and strength of the local healthcare system is a key consideration. In high income countries, existing infrastructures are usually used, while in less developed countries, the capacity for introducing new vaccines may need to be strengthened, particularly for vaccines administered beyond early childhood, such as the measles or human papillomavirus (HPV) vaccine. Reliable immunisation service funding is another important factor and low income countries often need external supplementary sources of finance. Many regions also obtain support in generating an evidence base for vaccination via initiatives created by organisations including World Health Organization (WHO), the Pan American Health Organization (PAHO), the Agence de Médecine Préventive and the Sabin Vaccine Institute. Strong monitoring and surveillance mechanisms are also required. An example is the efficient and low-cost approaches for measuring the impact of the hepatitis B control initiative and evaluating achievement of goals that have been established in the WHO Western Pacific region. A review of implementation strategies reveals differing degrees of success. For example, in the Americas, PAHO advanced a measles-mumps-rubella vaccine strategy, targeting different population groups in mass, catch-up and follow-up vaccination campaigns. This has had much success but coverage data from some parts of the region suggest that children are still not receiving all appropriate vaccines, highlighting problems with local service infrastructures. Stark differences in coverage levels are also observed among high income countries, as is the case with HPV vaccine implementation in the USA versus the UK and Australia, reflecting differences in delivery settings. Experience and research have shown which vaccine strategies work well and the factors that encourage success, which often include strong support from government and healthcare organisations, as well as tailored, culturally-appropriate local approaches to optimise outcomes.

Vaccine Adjuvants: from 1920 to 2015 and Beyond.

The concept of stimulating the body's immune response is the basis underlying vaccination. Vaccines act by initiating the innate immune response and activating antigen presenting cells (APCs), thereby inducing a protective adaptive immune response to a pathogen antigen. Adjuvants are substances added to vaccines to enhance the immunogenicity of highly purified antigens that have insufficient immunostimulatory capabilities, and have been used in human vaccines for more than 90 years. While early adjuvants (aluminum, oil-in-water emulsions) were used empirically, rapidly increasing knowledge on how the immune system interacts with pathogens means that there is increased understanding of the role of adjuvants and how the formulation of modern vaccines can be better tailored towards the desired clinical benefit. Continuing safety evaluation of licensed vaccines containing adjuvants/adjuvant systems suggests that their individual benefit-risk profile remains favorable. Adjuvants contribute to the initiation of the innate immune response induced by antigens; exemplified by inflammatory responses at the injection site, with mostly localized and short-lived effects. Activated effectors (such as APCs) then move to draining lymph nodes where they direct the type, magnitude and quality of the adaptive immune response. Thus, the right match of antigens and adjuvants can potentiate downstream adaptive immune responses, enabling the development of new efficacious vaccines. Many infectious diseases of worldwide significance are not currently preventable by vaccination. Adjuvants are the most advanced new technology in the search for new vaccines against challenging pathogens and for vulnerable populations that respond poorly to traditional vaccines.

Evidence of recombination between 3' and 5' LTRs in macaques inoculated with SIV DNA.

Proviral SIV DNA inoculation of macaques is an efficient method to initiate wild-type and attenuated SIV infections. However, we found that macaques inoculated with SIV DNA engineered to contain a single 105-bp deletion in the 3' nef/LTR overlap region had SIV sequences subsequently isolated that had partially or fully repaired the deletion with wild-type sequence. Animals inoculated with SIV DNA containing identical deletions in both the 5' and 3' LTRs did not repair the deletion. Recombination events occurred early, most likely by homologous recombination with sequences from the wild-type 5' LTR. This sequence analysis is the first demonstration of homologous recombination in vivo following administration of a single SIV strain.

A SOX9 defect of calmodulin-dependent nuclear import in campomelic dysplasia/autosomal sex reversal.

During mammalian sex determination, SOX9 is translocated into the nuclei of Sertoli cells within the developing XY gonad. The N-terminal nuclear localization signal (NLS) is contained within a SOX consensus calmodulin (CaM) binding region, thereby implicating CaM in nuclear import of SOX9. By fluorescence spectroscopy and glutaraldehyde cross-linking, we show that the SOX9 HMG domain and CaM interact in vitro. The formation of a SOX9.CaM binary complex is calcium-dependent and is accompanied by a conformational change in SOX9. A CaM antagonist, calmidazolium chloride (CDZ), was observed to block CaM recognition of SOX9 in vitro and inhibit both nuclear import and consequent transcriptional activity of SOX9 in treated cells. The significance of the SOX9-CaM interaction was highlighted by analysis of a missense SOX9 mutation, A158T, identified from a XY female with campomelic dysplasia/autosomal sex reversal (CD/SRA). This mutant binds importin beta normally despite defective nuclear import. Fluorescence and quenching studies indicate that in the unbound state, the A158T mutant shows a similar conformation to that of the WT SOX9, but in the presence of CaM, the mutant undergoes unusual conformational changes. Furthermore, SOX9-mediated transcriptional activation by cells expressing the A158T mutant is more sensitive to CDZ than cells expressing WT SOX9. These results suggest first that CaM is involved in the nuclear transport of SOX9 in a process likely to involve direct interaction and second, that CD/SRA can arise, at least in part, from a defect in CaM recognition, ultimately leading to reduced ability of SOX9 to activate transcription of cartilage and testes-forming genes.

Decreased neurotropism of nef long terminal repeat (nef/LTR)-deleted simian immunodeficiency virus.

Simian immunodeficiency virus (SIV) infection of macaques results in neurological abnormalities similar to those of human immunodeficiency virus (HIV)-associated dementia in humans and is a valuable system for the identification of viral neurotropic and neurovirulence factors. The authors recently established an SIV-macaque model where macaques can be infected with wild-type or nef/LTR-deleted SIVmac239 via administration of purified proviral DNA. In this study, the ability of wild-type and nef/LTR-deleted SIV infections to enter the cerebral spinal fluid (CSF) and brain was analyzed. In situ polymerase chain reaction (PCR) readily detected SIV gag DNA-positive cells in the mid-frontal gyrus and basal ganglia of the wild-type SIV-infected macaques, but not in nef/LTR-deleted SIV-infected or SIV-uninfected macaques. PCR on extracted DNA confirmed the in situ results, with multiple brain regions of the wild-type SIV-infected macaques positive for both gag and wild-type nef, whereas in the nef/LTR-deleted SIV-infected macaques, nef/LTR and gag DNA were undetectable. Further, macaques infected with nef/LTR-deleted SIV, which later became superinfected with wild-type SIV, also remained negative for SIV DNA in the brain by both in situ and extracted DNA techniques, despite having high levels of SIV RNA both in the CSF and plasma. This study provides evidence of the inability of nef/LTR-deleted SIV to initiate central nervous system (CNS) infection and suggests that, in the brain regions examined, nef/LTR-deleted viruses have either diminished neurotropism or insufficient systemic viral replication for entry into the CNS.