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Overbaugh J.,Fred Hutchinson Cancer Research Center | Morris L.,South African National Institute for Communicable Diseases
Cold Spring Harbor Perspectives in Medicine | Year: 2012

Neutralizing antibodies (NAbs) typically play a key role in controlling viral infections and contribute to the protective effect of many successful vaccines. In the case of HIV-1 infection, there is compelling data in experimental animal models that NAbs can prevent HIV-1 acquisition, although there is no similar data in humans and their role in controlling established infection in humans is also limited. It is clear HIV-specific NAbs drive the evolution of the HIV-1 envelope glycoprotein within an infected individual. The virus's ability to evade immune selection may be the main reason HIV-1 NAbs exert limited control during infection. The extraordinary antigenic diversity of HIV-1 also presents formidable challenges to defining NAbs that could provide broad protection against diverse circulating HIV-1 strains. Several new potent monoclonal antibodies (MAbs) have been identified, and are beginning to yield important clues into the epitopes common to diverse HIV-1 strains. In addition, antibodies can also act in concert with effector cells to kill HIV-infected cells; this could provide another mechanism for antibody-mediated control of HIV-1 replication. Understanding the impact of antibodies on HIV-1 transmission and pathogenesis is critical to helping move forward with rational HIV-1 vaccine design. © 2012 Cold Spring Harbor Laboratory Press; all rights reserved. Source


Lewis D.A.,South African National Institute for Communicable Diseases | Lewis D.A.,University of Witwatersrand | Lewis D.A.,University of Cape Town
Sexually Transmitted Infections | Year: 2010

Since the introduction of antibiotics in the 1930s, Neisseria gonorrhoeae has exhibited a remarkable ability to acquire novel genetic resistance determinants. Initially, sulphonamides were replaced by penicillin, while tetracyclines were prescribed for penicillin-allergic patients. With the advent of penicillinase-producing gonococci, spectinomycin was only briefly useful as alternative treatment and plasmid-mediated tetracycline resistance spread rapidly from the mid-1980s onwards. The fluoroquinolones followed but chromosomally mediated resistance appeared after only a decade of use. Seventy years on, we now face a global public health challenge of immense significance - the emergence of resistance to cephalosporins. With lack of investment in the search for new anti-gonococcal antimicrobial agents or vaccine research, the global spread of multiresistant gonococci can be seen. The impact of untreatable gonorrhoea on HIV transmission could be enormous in high-prevalence countries. This threat comes at a time when many national STI control programmes are weak. To delay the emergence of extensively drug-resistant gonorrhoea, public health systems require strengthening and novel strategies need implementing to enhance the therapeutic lifespan of the few antimicrobial agents that we have left. Source


Walaza S.,South African National Institute for Communicable Diseases
South African Medical Journal | Year: 2014

Here we provide recommendations for the use of viral vaccines in anticipation of the 2014 southern hemisphere influenza season. For a review of the 2013 influenza season, please refer to the National Institute for Communicable Diseases, National Health Laboratory Service website (http://www.nicd.ac.za). Source


Schoub B.D.,South African National Institute for Communicable Diseases | Schoub B.D.,University of Witwatersrand
Vaccine | Year: 2012

South Africa is currently the only country on the African continent using inactivated polio vaccine (IPV) for routine immunization in a sequential schedule in combination with oral polio vaccine (OPV). IPV is a component of an injectable pentavalent vaccine introduced nationwide in April 2009 and administered according to EPI schedule at 6, 10 and 14 weeks with a booster dose at 18 months. OPV is administered at birth and together with the first IPV dose at 6 weeks, which stimulates gut immune system producing a memory IgA response (OPV), followed by IPV to minimize the risk of vaccine associated paralytic polio (VAPP). OPV is also given to all children under 5 years of age as part of regular mass immunizations campaigns. The decision to incorporate IPV into the routine schedule was not based on cost-effectiveness, which it is not. Other factors were taken into account: Firstly, the sequence benefits from the initial mucosal contact with live(vaccine) virus which promotes the IgA response from subsequent IPV, as well as herd immunity from OPV, together with the safety of IPV. Secondly, given the widespread and increasing use of IPV in the developed world, public acceptance of vaccination in general is enhanced in South Africa which is classified as an upper middle income developing country. Thirdly, to address equity concerns because of the growing use of IPV in the private sector. Fourthly, the advent of combination vaccines facilitated the incorporation of IPV into the EPI schedule. © 2012 Elsevier Ltd. Source


Wain J.,University of East Anglia | Hendriksen R.S.,Technical University of Denmark | Mikoleit M.L.,Centers for Disease Control and Prevention | Keddy K.H.,South African National Institute for Communicable Diseases | And 2 more authors.
The Lancet | Year: 2015

Control of typhoid fever relies on clinical information, diagnosis, and an understanding for the epidemiology of the disease. Despite the breadth of work done so far, much is not known about the biology of this human-adapted bacterial pathogen and the complexity of the disease in endemic areas, especially those in Africa. The main barriers to control are vaccines that are not immunogenic in very young children and the development of multidrug resistance, which threatens efficacy of antimicrobial chemotherapy. Clinicians, microbiologists, and epidemiologists worldwide need to be familiar with shifting trends in enteric fever. This knowledge is crucial, both to control the disease and to manage cases. Additionally, salmonella serovars that cause human infection can change over time and location. In areas of Asia, multidrug-resistant Salmonella enterica serovar Typhi (S Typhi) has been the main cause of enteric fever, but now S Typhi is being displaced by infections with drug-resistant S enterica serovar Paratyphi A. New conjugate vaccines are imminent and new treatments have been promised, but the engagement of local medical and public health institutions in endemic areas is needed to allow surveillance and to implement control measures. © 2015 Elsevier Ltd. Source

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