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Inhibition of Plasmodium knowlesi merozoite invasion into human erythrocytes by antibodies raised against the parasite's secreted protein with altered thrombospondin repeat (SPATR)

Azlan UW, Cheong FW, Lau YL, Fong MY

Trop Biomed, 2024 Jun 01;41(2):190-195.
PMID: 39154272 DOI: 10.47665/tb.41.2.009

The Plasmodium secreted protein with an altered thrombospondin repeat (SPATR) has been known to play an important role in the malaria parasite's invasion into host erythrocytes. This protein is immunogenic and has been considered as one of the potential vaccine candidates against malaria parasite infection. Thus far, only a handful immunological studies have been carried out on P. knowlesi SPATR (PkSPATR), and none of these studies investigated the immunoprotective properties of the protein. In the present study, the ability of anti-PkSPATR antibodies to inhibit invasion of human erythrocytes was assessed in an in vitro merozoite invasion inhibition assay. The antibodies were harvested from the serum of a rabbit which was immunised with recombinat PkSPATR. Results from the merozoite invasion inhibition assay revealed significant antibody invasion inhibitory activity in a concentration dependent manner (concentration range: 0.375 - 3.00 mg/ml) with inhibition rate ranging from 20% to 32%. Future studies, such as anti-PkSPATR antibodies inhibitory effect on sporozoite invasion of human liver cells, need to be carried out to assess the potential of PkSPATR as a knowlesi malaria vaccine candidate.

Matched MeSH terms: Malaria Vaccines/immunology
Fulltext Development of Peptide Vaccines in Dengue

Reginald K, Chan Y, Plebanski M, Poh CL

Curr Pharm Des, 2018;24(11):1157-1173.
PMID: 28914200 DOI: 10.2174/1381612823666170913163904

Dengue is one of the most important arboviral infections worldwide, infecting up to 390 million people and causing 25,000 deaths annually. Although a licensed dengue vaccine is available, it is not efficacious against dengue serotypes that infect people living in South East Asia, where dengue is an endemic disease. Hence, there is an urgent need to develop an efficient dengue vaccine for this region. Data from different clinical trials indicate that a successful dengue vaccine must elicit both neutralizing antibodies and cell mediated immunity. This can be achieved by designing a multi-epitope peptide vaccine comprising B, CD8+ and CD4+ T cell epitopes. As recognition of T cell epitopes are restricted by human leukocyte antigens (HLA), T cell epitopes which are able to recognize several major HLAs will be preferentially included in the vaccine design. While peptide vaccines are safe, biocompatible and cost-effective, it is poorly immunogenic. Strategies to improve its immunogenicity by the use of long peptides, adjuvants and nanoparticle delivery mechanisms are discussed.

Matched MeSH terms: Dengue Vaccines/immunology*
Immuno-protective efficiency of feed-based whole-cell inactivated bivalent vaccine against Streptococcus and Aeromonas infections in red hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus)

Monir MS, Yusoff MSM, Zulperi ZM, Hassim HA, Zamri-Saad M, Amal MNA, et al.

Fish Shellfish Immunol, 2021 Jun;113:162-175.
PMID: 33857622 DOI: 10.1016/j.fsi.2021.04.006

Streptococcosis and motile aeromonad septicemia (MAS) are well-known diseases in tilapia culture, which cause mass mortality with significant economic losses. The development of feed-based bivalent vaccines in controlling these diseases has been initiated, however, the mechanisms of immunities and cross-protection in fish remain unclear. This study was conducted to assess the immuno-protective as well as the cross-protective efficacy of a newly developed feed-based bivalent vaccine against Streptococcus and Aeromonas infections in red hybrid tilapia. A total of five groups of fish were vaccinated orally through two different techniques; bivalent vaccine (inactivated Streptococcus iniae and Aeromonas hydrophila) sprayed on feed pellets (BS group); bivalent vaccine (inactivated S. iniae and A. hydrophila) incorporated in feed (BI group); monovalent inactivated S. iniae and A. hydrophila vaccine separately incorporated into feed as monovalent S. iniae (MS group) and monovalent A. hydrophila (MA group); and control group (without vaccine). The feed-based vaccine was delivered orally at 5% of body weight for five consecutive days. The booster doses were given in the same manner on weeks 2 and 6. Serum and skin mucus samples were collected to assess the IgM responses using indirect ELISA. The first administration of the feed-based vaccine stimulated the IgM levels that lasted until week 3, while the second booster ensured that the IgM levels remained high for a period of 16 weeks in the BI, MS and MA groups. The BI group developed a strong and significantly (P

Matched MeSH terms: Bacterial Vaccines/immunology*; Streptococcal Vaccines/immunology
Dengue vaccine in regions of endemic disease

Chew CH, Goh PP, Lim TO

N Engl J Med, 2016 04 07;374(14):1388.
PMID: 27050221 DOI: 10.1056/NEJMc1514451
Matched MeSH terms: Dengue Vaccines/immunology*
Fulltext Typhoid fever: present and future

Merican I

Med J Malaysia, 1997 Sep;52(3):299-308; quiz 309.
PMID: 10968104

Typhoid fever (TF), a systemic prolonged febrile illness, continues to be a worldwide health problem especially in developing countries where there is poor sanitation and poor standards of personal hygiene. The worldwide incidence of TF is estimated to be approximately 16 million cases annually with 7 million cases occurring annually in SE Asia alone. More than 600,000 people die of the disease annually. The pathogenesis of TF is beginning to be understood. The clinical features and diagnosis of TF are well known. New diagnostic methods have yet to gain universal acceptance. Traditional treatment with the first-line antibiotics (i.e. chloramphenicol, ampicillin and trimethoprim-sulphamethoxazole) though still being used in most developing countries are gradually being replaced with shorter courses of treatment with third generation cephalosporins or fluoroquinolones especially with the growing incidence of multi-drug resistant S typhi strains (MDR-ST). MDR-ST strains are particularly common in the Indian subcontinent; Pakistan and China. The presently available vaccines are far from satisfactory in terms of safety, efficacy and costs. Newer vaccines have been developed and are presently undergoing clinical trials in human volunteers.

Matched MeSH terms: Typhoid-Paratyphoid Vaccines/immunology
Fulltext Immunogenicity of a plasma-derived hepatitis B vaccine in children and adults

Sinniah M, Halimah M, Krishnamurthy T, Lye MS, Choo CH, Shamsiah I

Med J Malaysia, 1994 Dec;49(4):336-40.
PMID: 7674968

Immunisation of health care workers and staff working in laboratory and hospital settings has been implemented since 1988. However due to the high cost of currently available HBV vaccine, many health personnel outside the Ministry of Health are not being immunised. This study sought to determine the immunogenicity of three doses of a low cost plasma-derived Korean HBV vaccine on employees of an institute for mentally handicapped and their spouses and children. We found that the Hepatitis B Vaccine-KGCC to be safe and immunogenic. The response to 10 mcg and 20 mcg Hepatitis B Vaccine-KGCC after third dose was good with 100% seroconversion.

Matched MeSH terms: Hepatitis B Vaccines/immunology*
COVID-19 vaccines and herd immunity: Perspectives, challenges and prospects

Wong RSY

Malays J Pathol, 2021 Aug;43(2):203-217.
PMID: 34448786

The coronavirus disease 2019 (COVID-19) is one of the biggest public health threats in the 21st century. Nearly every country in the world has been affected by COVID-19. The magnitude of the problem, with over 179 million confirmed cases and 3.8 million deaths worldwide, has driven researchers to search for vaccines to combat the disease. The discovery and development of a new vaccine, from the initial stage to the vaccine finally reaching the patients, usually take many years. However, given the urgency of the situation, many clinical trials on the COVID-19 vaccines have been conducted at extraordinary speed, whereas several vaccines against SARS-CoV-2 are being administered worldwide. This article gives an overview of the different types of COVID-19 vaccines, with a focus on those with promising results and are commonly used worldwide. It also gives an overview of herd immunity and discusses the challenges in achieving herd immunity through the global vaccination campaigns. Last but not least, some strategies that may be used to address these challenges are discussed.

Matched MeSH terms: Vaccines/immunology*
Travel vaccination recommendations and infection risk in HIV-positive travellers

Chang L, Lim BCW, Flaherty GT, Torresi J

J Travel Med, 2019 Sep 02;26(6).
PMID: 31066446 DOI: 10.1093/jtm/taz034

BACKGROUND: With the advent of highly active antiretroviral drugs for the treatment of human immunodeficiency virus (HIV) it has become possible for people with HIV to travel to destinations that may place them at risk of a number of infectious diseases. Prevention of infections by vaccination is therefore of paramount importance for these travellers. However, vaccine responsiveness in HIV-positive individuals is not infrequently reduced compared to HIV-negative individuals. An understanding of the expected immune responses to vaccines in HIV-positive travellers is therefore important in planning the best approach to a pretravel consultation.
METHODS: A PubMed search was performed on HIV or acquired immune deficiency syndrome together with a search for specific vaccines. Review of the literature was performed to develop recommendations on vaccinations for HIV-positive travellers to high-risk destinations.
RESULTS: The immune responses to several vaccines are reduced in HIV-positive people. In the case of vaccines for hepatitis A, hepatitis B, influenza, pneumococcus, meningococcus and yellow fever there is a good body of data in the literature showing reduced immune responsiveness and also to help guide appropriate vaccination strategies. For other vaccines like Japanese encephalitis, rabies, typhoid fever, polio and cholera the data are not as robust; however, it is still possible to gain some understanding of the reduced responses seen with these vaccines.
CONCLUSION: This review provides a summary of the immunological responses to commonly used vaccines for the HIV-positive travellers. This information will help guide travel medicine practitioners in making decisions about vaccination and boosting of travellers with HIV.

Matched MeSH terms: Vaccines/immunology*
Preliminary study on serum immunoglobulin G responses following intramuscular inoculation of adjuvanted polyhydroxyalkanoate microparticles with Pasteurella multocida vaccine in white rats

Mohamed S, May Amelia TS, Abdullah Amirul AA, Abdul Wahid ME, Bhubalan K

Biologicals, 2021 Jun;71:51-54.
PMID: 33858743 DOI: 10.1016/j.biologicals.2021.03.002

A natural biodegradable polymer, polyhydroxyalkanoate (PHA), was adjuvanted with a vaccine seed to observe the biomaterial's ability in enhancing an immune response in rats. The adjuvant potential of PHA was tested using the whole-killed Pasteurella multocida B:2 (PMB2) vaccine in Sprague Dawley (SD) rats to detect changes in serum immunoglobulin G (IgG) and immunoglobulin M (IgM) responses. A common PHA, poly(3-hydroxybutyrate) [P(3HB)], from Bacillus megaterium UMTKB-1 was constructed into microparticles using the solvent evaporation method. Twelve SD rats were divided into four treatment groups: 1) non-treatment as negative control, 2) P(3HB) adjuvant, 3) PMB2 vaccine, and 4) adjuvanted-P(3HB)/PMB2 vaccine groups, which were intramuscularly vaccinated twice. Immunoglobulins IgG and IgM levels were used as markers of the immune response induced by the adjuvanted-P(3HB)/PMB2 vaccine and analysed over an eight-week study period. The group vaccinated specifically with adjuvanted-P(3HB)/PMB2 vaccine had higher concentrations of immunoglobulins compared to other treatment groups, hence demonstrating the potential of the adjuvant to enhance immune response. Findings showed a need to delay the delivery of the second booster dose to determine the appropriate regime for the adjuvanted-P(3HB)/PMB2 vaccine.

Matched MeSH terms: Bacterial Vaccines/immunology*
Fulltext Analysis of viral diversity for vaccine target discovery

Khan AM, Hu Y, Miotto O, Thevasagayam NM, Sukumaran R, Abd Raman HS, et al.

BMC Med Genomics, 2017 12 21;10(Suppl 4):78.
PMID: 29322922 DOI: 10.1186/s12920-017-0301-2

BACKGROUND: Viral vaccine target discovery requires understanding the diversity of both the virus and the human immune system. The readily available and rapidly growing pool of viral sequence data in the public domain enable the identification and characterization of immune targets relevant to adaptive immunity. A systematic bioinformatics approach is necessary to facilitate the analysis of such large datasets for selection of potential candidate vaccine targets.
RESULTS: This work describes a computational methodology to achieve this analysis, with data of dengue, West Nile, hepatitis A, HIV-1, and influenza A viruses as examples. Our methodology has been implemented as an analytical pipeline that brings significant advancement to the field of reverse vaccinology, enabling systematic screening of known sequence data in nature for identification of vaccine targets. This includes key steps (i) comprehensive and extensive collection of sequence data of viral proteomes (the virome), (ii) data cleaning, (iii) large-scale sequence alignments, (iv) peptide entropy analysis, (v) intra- and inter-species variation analysis of conserved sequences, including human homology analysis, and (vi) functional and immunological relevance analysis.
CONCLUSION: These steps are combined into the pipeline ensuring that a more refined process, as compared to a simple evolutionary conservation analysis, will facilitate a better selection of vaccine targets and their prioritization for subsequent experimental validation.

Matched MeSH terms: Viral Vaccines/immunology
Immunogenicity of hepatitis B vaccine in healthy Malaysian adults

Ton SH, Noriah R, Duraisamy G

Indian J Med Res, 1988 Jun;87:542-4.
PMID: 3240935
Matched MeSH terms: Viral Hepatitis Vaccines/immunology*
Immune response to influenza vaccine and pneumococcal polysaccharide vaccine under IL-6 signal inhibition therapy with tocilizumab

Tsuru T, Terao K, Murakami M, Matsutani T, Suzaki M, Amamoto T, et al.

Mod Rheumatol, 2014 May;24(3):511-6.
PMID: 24252023 DOI: 10.3109/14397595.2013.843743

To evaluate humoral immune response to influenza vaccine and polysaccharide pneumococcal vaccine in patients with rheumatoid arthritis (RA) or Castleman's disease (CD) during tocilizumab therapy.

Matched MeSH terms: Influenza Vaccines/immunology*; Pneumococcal Vaccines/immunology*
Recombinant vaccines

Barnard RT

Expert Rev Vaccines, 2010 May;9(5):461-3.
PMID: 20450319 DOI: 10.1586/erv.10.48

The Recombinant Vaccines: Strategies for Candidate Discovery and Vaccine Delivery conference, organized by EuroSciCon, hosted a group of UK-based and international scientists from as far afield as Malaysia and Australia. Genomic analyses of pathogens and elucidation of mechanisms of pathogenesis has advanced candidate discovery and development of vaccines. Therefore, it was timely that this conference featured, in addition to detailed expositions of target selection and clinical trials, presentations on manufacturability, scale-up and delivery of vaccines. Ten talks were presented. This meeting report describes the key topics presented and the themes that emerged from this conference.

Matched MeSH terms: Bacterial Vaccines/immunology*; Viral Vaccines/immunology*
Clinical responses in cows vaccinated with a developed prototype killed Staphylococcus aureus mastitis vaccine

Hambali IU, Bhutto KR, Jesse FFA, Lawan A, Odhah MN, Wahid AH, et al.

Microb Pathog, 2018 Nov;124:101-105.
PMID: 30114463 DOI: 10.1016/j.micpath.2018.08.017

Mastitis is an inflammatory condition of the udder that occurs as a result of the release of leucocytes into the udder in a response to bacterial invasion. The major causes of mastitis are an array of gram positive and negative bacteria, however, algae, virus, fungi, mechanical or thermal injury to the gland have also been identified as possible causes. Mastitis vaccines are yet to be developed using Malaysian local isolate of bacteria. The objective of the present experimental trial was to develop a monovalent vaccine against mastitis using S. aureus of Malaysian isolate and to evaluate the clinical responses such as temperature, respiratory rates and heart rates in vaccinated cows. S. aureus is a major causative bacteria in clinical and subclinical types of mastitis in cows. Four concentrations of the bacterin (106, 107, 108 and 109 cfu/ml of the local isolate of S. aureus) were prepared using Aluminium potassium sulfate adjuvant. Thirty cows were grouped into four treatment groups (B, C, D and E) with a fifth group as control (A). These groups were vaccinated intramuscularly(IM) with the prepared monovalent vaccine and its influence on the vital signs were intermittently measured. The mean of rectal temperature was significantly different (p˂ 0.05) at 0hr Post Vaccination [1]" in groups D and E (39.5 ± 0.15 °C and 39.4 ± 0.15 °C respectively) and at 3 h PV in groups C, D and E (39.8 ± 0.14 °C, 39.9 ± 0.14 °C and 40.3 ± 0.14 °C respectively) compared to the control group. This indicated a sharp increased rectal temperatures between 0hr and 3 h PV in groups C, D and E which later declined at 24 h PV. The mean of rectal temperature of group E was significantly different (p˂ 0.05) at weeks 1 and 2 PV (39.87 ± 0.19 °C and 39.80 ± 0.18 °C respectively) compared to the control group. The mean of heart rate was significantly different (p˂ 0.05) at week 1 PV in groups D and E (83.0 ± 3.8 beats/minute and 80.0 ± 3.8 °C respectively) compared to control. A trending decrease was however observed in heart rates of group E from weeks through 4 PV and in group D from weeks 1 through 3 PV. The mean of respiratory rates was significantly different (p˂ 0.05) at week 3 PV in group B and D (31.0 ± 1.2 breaths/minute and 28.0 ± 1.2 breaths/minute) compared to control. In conclusion, this study highlights responses of these vital signs due to vaccination against S. aureus causing mastitis in cows. To the best of our knowledge the findings of this study adds value to the shallow literature on vital signs alterations in cows vaccinated against mastitis as elevated levels of temperature and heart rates of group D and E indicated obvious response.

Matched MeSH terms: Bacterial Vaccines/immunology*; Staphylococcal Vaccines/immunology*
Fulltext Development of Novel Vaccines against Enterovirus-71

Yee PT, Poh CL

Viruses, 2015 Dec 30;8(1).
PMID: 26729152 DOI: 10.3390/v8010001

The hand, foot and mouth disease is caused by a group of Enteroviruses such as Enterovirus 71 (EV-A71) and Coxsackievirus CV-A5, CV-A8, and CV-A16. Mild symptoms of EV-A71 infection in children range from high fever, vomiting, rashes and ulcers in mouth but can produce more severe symptoms such as brainstem and cerebellar encephalitis, leading up to cardiopulmonary failure and death. The lack of vaccines and antiviral drugs against EV-A71 highlights the urgency of developing preventive and treatment agents against EV-A71 to prevent further fatalities. Research groups have developed experimental inactivated vaccines, recombinant Viral Protein 1 (VP1) vaccine and virus-like particles (VLPs). The inactivated EV-A71 vaccine is considered the safest viral vaccine, as there will be no reversion to the infectious wild type strain. The recombinant VP1 vaccine is a cost-effective immunogen, while VLPs contain an arrangement of epitopes that can elicit neutralizing antibodies against the virus. As each type of vaccine has its advantages and disadvantages, increased studies are required in the development of such vaccines, whereby high efficacy, long-lasting immunity, minimal risk to those vaccinated, safe and easy production, low cost, dispensing the need for refrigeration and convenient delivery are the major goals in their design.

Matched MeSH terms: Viral Vaccines/immunology*
Fulltext Recent advances in Toxoplasma gondii immunotherapeutics

Lim SS, Othman RY

Korean J Parasitol, 2014 Dec;52(6):581-93.
PMID: 25548409 DOI: 10.3347/kjp.2014.52.6.581

Toxoplasmosis is an opportunistic infection caused by the protozoan parasite Toxoplasma gondii. T. gondii is widespread globally and causes severe diseases in individuals with impaired immune defences as well as congenitally infected infants. The high prevalence rate in some parts of the world such as South America and Africa, coupled with the current drug treatments that trigger hypersensitivity reactions, makes the development of immunotherapeutics intervention a highly important research priority. Immunotherapeutics strategies could either be a vaccine which would confer a pre-emptive immunity to infection, or passive immunization in cases of disease recrudescence or recurrent clinical diseases. As the severity of clinical manifestations is often greater in developing nations, the development of well-tolerated and safe immunotherapeutics becomes not only a scientific pursuit, but a humanitarian enterprise. In the last few years, much progress has been made in vaccine research with new antigens, novel adjuvants, and innovative vaccine delivery such as nanoparticles and antigen encapsulations. A literature search over the past 5 years showed that most experimental studies were focused on DNA vaccination at 52%, followed by protein vaccination which formed 36% of the studies, live attenuated vaccinations at 9%, and heterologous vaccination at 3%; while there were few on passive immunization. Recent progress in studies on vaccination, passive immunization, as well as insights gained from these immunotherapeutics is highlighted in this review.

Matched MeSH terms: Protozoan Vaccines/immunology
[A possible fifth dengue virus serotype]

da Silva Voorham JM

Ned Tijdschr Geneeskd, 2014;158:A7946.
PMID: 25227888

Sylvatic dengue viruses are both evolutionarily and ecologically distinguishable from the human dengue virus (DENV). Sporadic episodes of sylvatic human infections in West Africa and Southeast Asia suggest that sylvatic DENV regularly come into contact with human beings. Following a study on the sylvatic transmission cycle in Malaysia in 2007, researchers announced that a new DENV serotype, DENV-5, had been discovered. Scientists are still sceptical about these new findings, and indicate that more data is necessary to determine whether this 'new' virus really is a different serotype or whether it is a variant of one of the four DENV serotypes already known. The good news is that this new variant has not yet established itself in the human transmission cycle. However, if it really is a new serotype this will have implications for the long-term control of dengue using vaccines currently under development.

Matched MeSH terms: Dengue Vaccines/immunology
Challenges in reducing dengue burden; diagnostics, control measures and vaccines

Lam SK

Expert Rev Vaccines, 2013 Sep;12(9):995-1010.
PMID: 24053394 DOI: 10.1586/14760584.2013.824712

Dengue is a major public health concern worldwide, with the number of infections increasing globally. The illness imposes the greatest economic and human burden on developing countries that have limited resources to deal with the scale of the problem. No cure for dengue exists; treatment is limited to rehydration therapy, and with vector control strategies proving to be relatively ineffective, a vaccine is an urgent priority. Despite the numerous challenges encountered in the development of a dengue vaccine, several vaccine candidates have shown promise in clinical development and it is believed that a vaccination program would be at least as cost-effective as current vector control programs. The lead candidate vaccine is a tetravalent, live attenuated, recombinant vaccine, which is currently in Phase III clinical trials. Vaccine introduction is a complex process that requires consideration and is discussed here. This review discusses the epidemiology, burden and pathogenesis of dengue, as well as the vaccine candidates currently in clinical development.

Matched MeSH terms: Dengue Vaccines/immunology*
Efficacy of spray administration of formalin-killed Streptococcus agalactiae in hybrid Red Tilapia

Noraini O, Sabri MY, Siti-Zahrah A

J Aquat Anim Health, 2013 Jun;25(2):142-8.
PMID: 23724958 DOI: 10.1080/08997659.2013.781553

An initial evaluation of spray vaccination was carried out with 60 hybrid Red Tilapia Oreochromis spp., divided into three groups that consisted of 10 fish per group with duplicates. The formalin-killed cells (FKCs) of Streptococcus agalactiae were administered once to group 1 by spray and once daily for five consecutive days to group 2. Group 3 remained as the untreated control group and was sprayed with normal saline. A booster was given twice to all the groups, once at the second week and again at the fourth week after the first vaccination. After this initial evaluation, a challenge study was conducted with 40 tilapia divided into two groups that consisted of 10 fish per group with duplicates. Group 1 was vaccinated with FKCs of S. agalactiae by a single spray administration while group 2 remained as the untreated control group. A booster was given twice using the same protocol as in the initial evaluation. After 6 weeks, fish from one of the duplicate tanks from each of groups 1 and 2 were challenged with pathogenic S. agalactiae by intraperitoneal (IP) injection, while fish in another tank were challenged through immersion. Based on the observations, serum immunoglobulin M (IgM) levels were significantly higher (P < 0.05) in the challenged fish than in the either the preexposed fish or the control group 1 week after the initial exposure. However, no significant differences (P > 0.05) were noted between challenged groups 1 and 2. In addition, no significant differences (P > 0.05) were observed between the frequencies of exposure. The mucus IgM level, however, remained high after each booster until the end of the 8-week study period. Meanwhile, serum IgM levels decreased after the challenge. A higher percentage of survival was noted for fish challenged through immersion (80%) compared with IP injection (70%). These results suggested that single spray exposure was able to induce IgM, which gave moderate to high protection during the challenge study.

Matched MeSH terms: Bacterial Vaccines/immunology*
Fulltext Capsular serotype and antibiotic resistance of Streptococcus pneumoniae isolates in Malaysia

Le CF, Palanisamy NK, Mohd Yusof MY, Sekaran SD

PLoS One, 2011;6(5):e19547.
PMID: 21603602 DOI: 10.1371/journal.pone.0019547

BACKGROUND: Streptococcus pneumoniae is a major causative agent of severe infections, including sepsis, pneumonia, meningitis, and otitis media, that has since become a major public health concern. In this study, the serotypes distribution of pneumococcal isolates was investigated to predict the efficacy of the 7-valent pneumococcal conjugate vaccine (PCV7) among the Malaysian populations.
METHODOLOGY/PRINCIPAL FINDINGS: A total of 151 clinical isolates were serotyped using multiplex PCR assays. Out of them, there were 21.2% penicillin-resistant, 29.1% penicillin-intermediate, and 49.7% penicillin-susceptible S. pneumoniae strains. Serotypes detected among the Malaysian isolates were 1, 3, 10A, 11A/11D, 12F/12A, 14, 15A, 15B/15C, 16F, 18C/18B/18A/18F, 19A, 19F, 23F, 35B, 35F/47F, 6A/6B, 7C/7B/40, 7F/7A, 9V/9A, and 34. Serotype 19F and 23F were the two most prevalent serotypes detected. Serotypes are highly associated with invasiveness of isolates (p = 0.001) and penicillin susceptibility (p<0.001). Serotype 19F was observed to have increased resistance against penicillin while serotype 19A has high invasive tendency. Age of patients was an important factor underlying the pneumococcal serotypes (p = 0.03) and clinical sites of infections (p<0.001). High prevalence of pneumococcal isolates were detected among children <5 years old at nasopharyngeal sites while elderly adults ≥60 years old were at increased risk for pneumococcal bacteremia.
CONCLUSION/SIGNIFICANCE: Current study revealed that a number of serotypes, especially those associated with high penicillin resistance, have been formulated in the PCV7. Therefore, the protections expected from the routine use of PCV7 would be encouraging for the Malaysian. However, it is not possible to predict serotypes that might become predominant in the future and hence continued surveillance of circulating serotypes will be needed.

Matched MeSH terms: Pneumococcal Vaccines/immunology*

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