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Fulltext Molecular identification and histopathological study of natural Streptococcus agalactiae infection in hybrid tilapia (Oreochromis niloticus)

Laith AA, Ambak MA, Hassan M, Sheriff SM, Nadirah M, Draman AS, et al.

Vet World, 2017 Jan;10(1):101-111.
PMID: 28246454 DOI: 10.14202/vetworld.2017.101-111

AIM: The main objective of this study was to emphasize on histopathological examinations and molecular identification of Streptococcus agalactiae isolated from natural infections in hybrid tilapia (Oreochromis niloticus) in Temerloh Pahang, Malaysia, as well as to determine the susceptibility of the pathogen strains to various currently available antimicrobial agents.
MATERIALS AND METHODS: The diseased fishes were observed for variable clinical signs including fin hemorrhages, alterations in behavior associated with erratic swimming, exophthalmia, and mortality. Tissue samples from the eyes, brain, kidney, liver, and spleen were taken for bacterial isolation. Identification of S. agalactiae was screened by biochemical methods and confirmed by VITEK 2 and 16S rRNA gene sequencing. The antibiogram profiling of the isolate was tested against 18 standard antibiotics included nitrofurantoin, flumequine, florfenicol, amoxylin, doxycycline, oleandomycin, tetracycline, ampicillin, lincomycin, colistin sulfate, oxolinic acid, novobiocin, spiramycin, erythromycin, fosfomycin, neomycin, gentamycin, and polymyxin B. The histopathological analysis of eyes, brain, liver, kidney, and spleen was observed for abnormalities related to S. agalactiae infection.
RESULTS: The suspected colonies of S. agalactiae identified by biochemical methods was observed as Gram-positive chained cocci, β-hemolytic, and non-motile. The isolate was confirmed as S. agalactiae by VITEK 2 (99% similarity), reconfirmed by 16S rRNA gene sequencing (99% similarity) and deposited in GenBank with accession no. KT869025. The isolate was observed to be resistance to neomycin and gentamicin. The most consistent gross findings were marked hemorrhages, erosions of caudal fin, and exophthalmos. Microscopic examination confirmed the presence of marked congestion and infiltration of inflammatory cell in the eye, brain, kidney, liver, and spleen. Eye samples showed damage of the lens capsule, hyperemic and hemorrhagic choroid tissue, and retina hyperplasia accompanied with edema. Brain samples showed perivascular and pericellular edema and hemorrhages of the meninges. Kidney samples showed hemorrhage and thrombosis in the glomeruli and tubules along with atrophy in hematopoietic tissue. Liver samples showed congestion of the sinusoids and blood vessel, thrombosis of portal blood vessel, and vacuolar (fatty) degeneration of hepatocytes. Spleen samples showed large thrombus in the splenic blood vessel, multifocal hemosiderin deposition, congestion of blood vessels, and multifocal infiltration of macrophages.
CONCLUSION: Therefore, it can be concluded that pathological changes in tissues and organs of fish occur proportionally to the pathogen invasion, and because of their high resistance, neomycin and gentamicin utilization in the prophylaxis or treatment of S. agalactiae infection should be avoided.

Matched MeSH terms: Streptococcus agalactiae
Feed-based vaccination regime against streptococcosis in red tilapia, Oreochromis niloticus x Oreochromis mossambicus

Ismail MS, Siti-Zahrah A, Syafiq MR, Amal MN, Firdaus-Nawi M, Zamri-Saad M

BMC Vet Res, 2016;12(1):194.
PMID: 27608936 DOI: 10.1186/s12917-016-0834-1

Streptococcosis is an important disease of tilapia throughout the world. In Malaysia, streptococcosis outbreak was commonly reported during the 3-month period of high water temperature between April and July. This study describes the duration of protection following single and double booster dose regimes against streptococcosis in tilapia using a feed-based vaccine containing formalin-killed Streptococcus agalactiae. A total of 510 tilapias of 120 ± 10 g were selected and divided into 3 groups. Fish of Group 1 were vaccinated at weeks 0 and 2 (single booster group) while fish of Group 2 were vaccinated at weeks 0, 2 and 6 (double booster group) with a feed-based vaccine against streptococcosis. Fish of Group 3 was not vaccinated. Serum samples were collected weekly to determine the antibody level while samples of eye, brain and kidney were collected for bacterial isolation. At week 10, all fish were challenged with live S. agalactiae and the survival rate was determined.

Matched MeSH terms: Streptococcus agalactiae
Fulltext Post-partum invasive group b Streptococcus infection with fatal outcome: a case report

Siti Zulaikha Zakariah, Syafinaz Amin Nordin, Khairul Anuar Zainun, Asyraff Md Najib

Malaysian Journal of Medicine and Health Sciences, 2018;14(3):57-59.
MyJurnal

Group B streptococcus (GBS) is generally known to cause severe disease in the neonate and immunocompromised adults. GBS in the pregnant mother is rare and can potentially be fatal. Clinical presentation can be as mild as an uncomplicated urinary tract infection or serious invasive disease in the form of bacteremia, chorioamnionitis, endometritis and septic abortion. We report a case of a 46-year-old Para 3 lady, post-partum day 12, whom was found dead at home. Prior to her death, she had intermittent fever and abnormal lochia. Autopsy findings indicate GBS endometritis and bacteraemia. She was never screened for GBS. The cost-effectiveness of universal GBS screening needs to be explored to reduce maternal and neonatal morbidity due to GBS.

Matched MeSH terms: Streptococcus agalactiae
Mother with post-partum group B Streptococcus meningitis and cerebellar abscess

Ghani NA, Jaafar R, Ishak S, Zainuddin AA, Mukari SA, Mahdy ZA

J Obstet Gynaecol Res, 2007 Apr;33(2):195-8.
PMID: 17441895

We report the case of a 25-year-old Malay woman, admitted for preterm delivery at 35 weeks' gestation. Vaginal swab did not isolate any organism. She delivered a baby girl who developed respiratory distress syndrome, requiring ventilation. Although chest radiograph showed hyaline membrane disease with pneumonia, septic workout was negative. The mother was discharged on the next day. Seven days postpartum, the mother presented with fever and fits and was diagnosed to have meningo-encephalitis. Lumbar puncture isolated group B Streptococcus (GBS) and MRI revealed a superior cerebellar abscess. She was treated and survived the episode. This case illustrates the uncommon situation where GBS infection was confirmed via maternal septic workout rather than neonatal, although both presented with severe disease.

Matched MeSH terms: Streptococcus agalactiae*
Efficacy of live attenuated vaccine derived from the Streptococcus agalactiae on the immune responses of Oreochromis niloticus

Laith AA, Abdullah MA, Nurhafizah WWI, Hussein HA, Aya J, Effendy AWM, et al.

Fish Shellfish Immunol, 2019 Jul;90:235-243.
PMID: 31009810 DOI: 10.1016/j.fsi.2019.04.052

Streptococcus agalactiae species have been recognized as the main pathogen causing high mortality in fish leading to significant worldwide economical losses to the aquaculture industries. Vaccine development has become a priority in combating multidrug resistance in bacteria; however, there is a lack of commercial live attenuated vaccine (LAV) against S. agalactiae in Malaysia. The aim of this study is to compare two methods using attenuated bacteria as live vaccine and to evaluate the efficacy of selected LAV on the immune responses and resistance of Oreochromis niloticus (tilapia) against S. agalactiae. The LAV derived from S. agalactiae had been weakened using the chemical agent Acriflavine dye (LAV1), whereas the second vaccine was weakened using serial passages of bacteria on broth media (LAV2). Initial immunization was carried out only on day one, given twice-in the morning and evening, for the 42 day period. Serum samples were collected to determine the systemic antibody (IgM) responses and lysozymal (LSZ) activity using ELISA. On day 43 after immunization, the fish were injected intraperitoneally (i.p) with 0.1 mL of S. agalactiae at LD50 = 1.5 × 105 (CFU)/fish. Fish were monitored daily for 10 days. Clinical signs, mortality and the relative percent of survival (RPS) were recorded. Trial 1 results showed a significant increased (P 

Matched MeSH terms: Streptococcus agalactiae/immunology*
Pathological changes in red tilapias (Oreochromis spp.) naturally infected by Streptococcus agalactiae

Zamri-Saad M, Amal MN, Siti-Zahrah A

J Comp Pathol, 2010 Aug-Oct;143(2-3):227-9.
PMID: 20334871 DOI: 10.1016/j.jcpa.2010.01.020

The pathological changes present in 300 red tilapias (Oreochromis spp.) naturally infected by Streptococcus agalactiae are described. The most consistent gross findings were marked congestion of internal organs, particularly the liver, spleen and kidneys. Other features included exophthalmos, softening of the brain and the occasional accumulation of fluid within the abdominal cavity. Microscopical examination confirmed the presence of marked congestion of the liver, spleen and kidneys. The endothelial cells lining major blood vessels of the liver and occasionally the spleen were swollen and vacuolated. There was evidence of vascular thrombosis with infarction of surrounding tissue. Bacterial colonies were noted within and immediately surrounding the affected blood vessels. The meninges were thickened by the infiltration of numerous heterophils. Similar infiltrates of heterophils and lymphocytes were observed in the lamina propria of the intestine. The kidneys were severely congested and haemorrhagic, with extensive interstitial nephritis.

Matched MeSH terms: Streptococcus agalactiae*
The effect of feed-based vaccination on tilapia farm endemic for streptococcosis

Ismail MS, Syafiq MR, Siti-Zahrah A, Fahmi S, Shahidan H, Hanan Y, et al.

Fish Shellfish Immunol, 2017 Jan;60:21-24.
PMID: 27864157 DOI: 10.1016/j.fsi.2016.11.040

A tilapia farm experiencing endemic streptococcosis was selected to study the effect of vaccination with a feed-based vaccine on naturally ocurring streptococcosis. A total of 9000 red tilapia, Oreochromis niloticus × Oreochromis mossambicus of 100 ± 20 g were divided into 9 cages. Fish of Group 1 in cages 1, 2 and 3 were not vaccinated. Group 2 in cages 4, 5 and 6 were vaccinated on days 0 and 14 (single booster) while Group 3 in cages 7, 8 and 9 were vaccinated on days 0, 14 and 42 (double booster). Vaccination was done by oral administration of the feed-based bacterin vaccine at 4% bodyweight. Samples of serum for antibody study and the brain, eyes and kidney for bacterial isolation were collected at 14-day intervals. The study was carried out during the critical months between April and June. Following vaccination and booster, there was significant (p

Matched MeSH terms: Streptococcus agalactiae/immunology*
Study on Streptococcus agalactiae infection in Javanese medaka (Oryzias javanicus Bleeker, 1854) model

Amal MNA, Ismail A, Saad MZ, Md Yasin IS, Nasruddin NS, Mastor SS, et al.

Microb Pathog, 2019 Jun;131:47-52.
PMID: 30940607 DOI: 10.1016/j.micpath.2019.03.034

This study determines the median lethal dose, and describes the clinico-pathological changes and disease development following Streptococcus agalactiae infection in Javanese medaka model. Javanese medakas were infected with S. agalactiae via intraperitoneal (IP) from 104 to 108 CFU/mL, and immersion (IM) route from 103 to 107 CFU/mL. The LD50-240h and clinico-pathological changes of the fish was determined until 240 h post infection (hpi). Next, the disease development was determined for 96 hpi in the fish following IP and IM infection at 103 CFU/mL and 104 CFU/mL, respectively. The LD50-240h of S. agalactiae in Javanese medaka was lower following IP injection (4.5 × 102 CFU/mL), compared to IM route (3.5 × 103 CFU/mL). The clinical signs included separating from the schooling group, swimming at the surface of water column, lethargy, erratic swimming pattern, corneal opacity and exophthalmia. Histopathological examinations revealed generalized congestion in almost all internal organs, particularly in liver and brain, while the kidney displayed tubular necrosis. Both IP and IM routes showed significant positive correlation (p 

Matched MeSH terms: Streptococcus agalactiae/pathogenicity*
The effects of fish gender on susceptibility to acute Streptococcus agalactiae infection in Javanese medaka Oryzias javanicus

Amal MNA, Zarif ST, Suhaiba MS, Aidil MRM, Shaqinah NN, Zamri-Saad M, et al.

Microb Pathog, 2018 01;114:251-254.
PMID: 29217326 DOI: 10.1016/j.micpath.2017.11.069

This study describes the susceptibility of different fish gender following acute Streptococcus agalactiae infection by using Javanese medaka Oryzias javanicus as test fish. The fish were grouped into four groups, which were: (1) all-male; (2) all-female; (3) mixed-gender (1 male: 1 female ratio); and (4) control non-infected (1 male: 1 female ratio). The fish in group 1, 2 and 3 were intraperitoneally exposed to 5.4 × 108 CFU/mL of S. agalactiae, while for group 4, the fish were exposed using sterile broth. The main clinical signs and histopathological changes of infected Javanese medaka were commonly observed in S. agalactiae infected fishes. However, no difference on clinical signs and histopathological changes of fish in group 1, 2 and 3 were noticed. The Javanese medaka mortality in group 1, 2 and 3 were observed from 4 h post infection (hpi) to 6 hpi, with the cumulative mortality from 3% to 30%. Then, the mortality increased at 12 hpi, with the range from 53% to 80%. However, 100% of the infected fish dead at 24 hpi. No clinical sign, histopathological change and fish mortality recorded in group 4. Generally, the clinical signs, mortality patterns, cumulative mortality and histopathological changes of Javanese medaka infected by S. agalactiae did not show any difference between the all-male, all-female and mixed-gender groups. This indicates that the susceptibility of fish to S. agalactiae infection is not influenced by their gender.

Matched MeSH terms: Streptococcus agalactiae/pathogenicity*
Development and efficacy of feed-based recombinant vaccine encoding the cell wall surface anchor family protein of Streptococcus agalactiae against streptococcosis in Oreochromis sp

Nur-Nazifah M, Sabri MY, Siti-Zahrah A

Fish Shellfish Immunol, 2014 Mar;37(1):193-200.
PMID: 24486904 DOI: 10.1016/j.fsi.2014.01.011

This study was carried out to determine the antibody responses and protective capacity of an inactivated recombinant vaccine expressing the cell wall surface anchor family protein of Streptococcus agalactiae following oral vaccination against streptococcosis in tilapia. Tilapia were vaccinated orally with 10(6) CFU/mL of the recombinant vaccine incorporated in feed (feed-based recombinant vaccine) (vaccinated group or Group 1), 10(6) CFU/mL of pET-32 Ek/LIC vector without cell wall surface anchor family protein (control group or Group 2), 10(6) CFU/mL of formalin-killed cells of S. agalactiae vaccine incorporated in feed was also prepared (feed-based vaccine) (vaccinated group or Group 3), and unvaccinated control group or Group 4 (fed with commercial pellets). During the course of study, serum, mucus and gut lavage fluid were collected to evaluate the antibody levels via enzyme-linked immunosorbent assay (ELISA). The results showed that tilapia immunized with the feed-based recombinant vaccine developed a strong and significantly (P

Matched MeSH terms: Streptococcus agalactiae/immunology*
Assessment of in vitro antioxidant, antibacterial and immune activation potentials of aqueous and ethanol extracts of Phyllanthus niruri

Amin ZA, Abdulla MA, Ali HM, Alshawsh MA, Qadir SW

J Sci Food Agric, 2012 Jul;92(9):1874-7.
PMID: 22231455 DOI: 10.1002/jsfa.5554

Recently much attention has been paid to biologically active plants because of their low production cost and fewer adverse effects compared with chemical drugs. In the present investigation the bioactivity of Phyllanthus niruri ethanol and aqueous extracts was evaluated in vitro.

Matched MeSH terms: Streptococcus agalactiae/drug effects
Group B streptococcus: maternal carriage rate and early neonatal septicaemia

Lim CT, Thong MK, Parasakthi N, Ngeow YF

Ann Acad Med Singap, 1997 Jul;26(4):421-5.
PMID: 9395802

Between January 1984 and December 1994, 30 cases of early neonatal group B streptococcus (GBS) septicaemia were managed in the Neonatal Unit, University Hospital, Kuala Lumpur. Two neonates were outborn and 28 were inborn, giving an average annual incidence of neonatal GBS septicaemia of 0.4/1000 livebirths among inborn babies. In a separate survey over a three-month period, GBS genital carriage rate among 196 parturients was found to be 9.7%. Of the infants with GBS septicaemia, the mean gestational age was 37.5 +/- 3.8 weeks and the mean birthweight was 2540 +/- 716 g. Twelve (40%) were preterm infants and 14 (47%) were low birthweight infants. Male and female infants were almost equally affected. Prolonged rupture of membranes and maternal pyrexia accounted for only 5 (17%) and 3 (10%) of the cases respectively. Twenty-four (80%) neonates had onset of symptoms within 6 hours of life and respiratory symptoms were observed in 24 (80%) of the cases, while meningitis was uncommon. Six (20%) neonates died. Preterm and low birthweight infants had higher mortality than their term counterparts: 42% versus 6% and 36% versus 6% respectively. Of those who died, 4 (67%) required respiratory support right from birth and the mean time of onset of symptoms was 4 hours (range 0 to 21 hours) and the duration of survival was only 28.8 hours (range 12 to 38 hours). As the incidence of neonatal GBS septicaemia was low, mass screening and chemoprophylaxis for GBS were not recommended. All the GBS isolates were sensitive to penicillin and ampicillin, thus one of these antibiotics should be included in the antimicrobial therapy of septic neonates.

Matched MeSH terms: Streptococcus agalactiae/isolation & purification*
Biofilm is associated with chronic streptococcal meningoencephalitis in fish

Isiaku AI, Sabri MY, Ina-Salwany MY, Hassan MD, Tanko PN, Bello MB

Microb Pathog, 2017 Jan;102:59-68.
PMID: 27890651 DOI: 10.1016/j.micpath.2016.10.029

Biofilms are aggregates of attached microbial organisms whose existence on tissues is often recognised as a mechanism for the establishment of most chronic diseases. Herein we investigated the ability of piscine Streptococcus agalactiae, an important aquatic pathogen, for adaptation to this sessile lifestyle in vitro and in the brain of a tilapia fish model. Piscine S. agalactiae exhibited a weak attachment to polystyrene plates and expressed a low biofilm phenotype under the study conditions. Furthermore, fluorescent in situ hybridization and confocal laser scanning microscopy revealed discrete aggregates of attached S. agalactiae within brain tissues and around meningeal surfaces. They were embedded in an exopolysaccharide containing matrix, intractable to inflammatory response and showed some level of resistance to penicillin despite proven susceptibility on sensitivity test. Intracellular bacterial aggregates were also observed, moreover, antibody mediated response was not demonstrated during infection. Nucleated erythrocytes appear to facilitate brain invasion possibly via the Trojan horse mechanism leading to a granulomatous inflammation. We have demonstrated that biofilm is associated with persistence of S. agalactiae and the development of chronic meningoencephalitis in fish.

Matched MeSH terms: Streptococcus agalactiae/drug effects
Late onset group b beta-hemolytic streptococcus infection in a neonate manifesting as a urinary tract infection: a rare clinical presentation

Zurina Z, Rohani A, Neela V, Norlijah O

Southeast Asian J Trop Med Public Health, 2012 Nov;43(6):1470-3.
PMID: 23413711

Group B beta-hemolytic streptococcus (GBS) sepsis is a serious bacterial infection in neonates, with significant morbidity and mortality. We report here a neonate with late onset GBS infection manifesting as a urinary tract infection (UTI) in an infant presenting with prolonged neonatal jaundice. The pathogenesis of this late onset is postulated.

Matched MeSH terms: Streptococcus agalactiae/isolation & purification
Fulltext Neonatal group B beta-haemolytic streptococcal infection in Kuala Lumpur

Minhaj AA, Jamal F, Mohamed R

Med J Malaysia, 1980 Dec;35(2):117-21.
PMID: 7022149

First six cases of neonatal group B beta-haemolytic streptococcal sepsis in GHKL & Maternity Hospital K.L. were reported and in one third, it was fatal. Five of the cases were 'early - onset' type and one was 'late - onset' type. While maternal infant transmission of the disease is important in the 'early - onset' type, environmental sources of infection are also significant. No gestational age or birthweight is spared from the disease. Finally, there are cases of 'early - onset' GBS sepsis presenting like hyaline membrane disease of the newborn and it is important to find ways to distinguish them which so far has not been satisfactory.

Matched MeSH terms: Streptococcus agalactiae
Fulltext Screening of antenatal mothers and prevention of perinatal group B streptococcal infection

Raj, M., Razali N,, Sulaiman, S.

JUMMEC, 2009;12(1):27-30.
MyJurnal

The objectives of this study were: (1) to detect group B streptococcus (GBS) carriers among antenatal patients during pregnancy ( 35 to 37 weeks) in the University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia, and (2) to give antibiotic prophylaxis during the intrapartum period for the GBS carrier patients. The aim is to prevent early onset of GBS infection in newborn. This pilot study was carried out from 1st July 2005 to 31st August 2005. It is a prospective study involving 56 pregnant women who were seen at the antenatal clinic in the UMMC between 35 to 37 weeks gestation. High vaginal swab and low vaginal together with endoanal swab were taken for culture and sensitivity. The antibiotic prophylaxis was started early in the intrapartum period for patients with positive culture for GBS. GBS was detected in 18 patients which contributes to about 32% of the study population. The proper choice of antibiotic is important in successful disease prevention.

Study site: Obstretic and gynaecological clinic, University Malaya Medical Centre (UMMC)

Matched MeSH terms: Streptococcus agalactiae
Early-onset sepsis in Malaysian neonatal intensive care units

Boo NY, Ang EBK, Neoh SH, Ang EL, Chee SC

Malays J Pathol, 2022 Dec;44(3):443-459.
PMID: 36591712

OBJECTIVES: To determine the incidence, causative pathogens, morbidities, mortality, and risk factors associated with blood culture-positive early-onset sepsis (EOS, ≤72 hours of age) in symptomatic neonates admitted to the neonatal intensive care units (NICUs) of a middle-income country.
STUDY DESIGN: Retrospective cohort study using data submitted prospectively to the Malaysian National Neonatal Registry (MNNR).
SETTING: 44 Malaysian NICUs.
PARTICIPANTS: All neonates born in 2015- 2020.
RESULTS: EOS was reported in 991 neonates. The annual incidence of EOS increased from 0.46 to 0.49/1000 livebirths over the six years. The most common pathogen was Streptococcus agalactiae or Group B haemolytic streptococcus (GBS) (n=388, 39.2%), followed by Escherichia coli (E. coli) (n=80, 8.1%), Klebsiella spp (n=73, 7.4%), coagulase negative staphylococcus (CONS) (n=73, 7.4%), Pseudomonas spp (n=44, 4.4%) and methicillin-sensitive Staphylococcus aureus (n=34, 3.4%). The incidence of EOS due to GBS increased from 0.17 to 0.22/1000 livebirths. Morbidities and mortality were higher in those with EOS than without EOS. Multiple logistic regression analysis showed that Indian ethnic group, chorioamnionitis, gestation≥37weeks, female, spontaneous vaginal delivery, instrumental delivery, and surfactant therapy were significantly associated with increased risk of EOS due to GBS. Four factors were significantly associated with increased risk of non-GBS EOS (outborns, birthweight lt;1000 g, vaginal delivery, and surfactant therapy). Early continuous positive airway pressure was associated with significantly lower risk of EOS.
CONCLUSION: The incidence of EOS showed an increasing trend in Malaysian NICUs. GBS was the most common causative pathogen. Several modifiable risk factors associated with EOS have been identified.

Matched MeSH terms: Streptococcus agalactiae
Hot water extract of Pleurotus pulmonarius stalk waste enhances innate immune response and immune-related gene expression in red hybrid tilapia Oreochromis sp. following challenge with pathogen-associated molecular patterns

Ching JJ, Shuib AS, Abdullah N, Majid NA, Taufek NM, Sutra J, et al.

Fish Shellfish Immunol, 2021 Sep;116:61-73.
PMID: 34157396 DOI: 10.1016/j.fsi.2021.06.005

In aquaculture, commercial fish such as red hybrid tilapia are usually raised at high density to boost the production within a short period of time. This overcrowded environment, however, may cause stress to the cultured fish and increase susceptibility to infectious diseases. Antibiotics and chemotherapeutics are used by fish farmers to overcome these challenges, but this may increase the production cost. Studies have reported on the potential of mushroom polysaccharides that can act as immunostimulants to enhance the immune response and disease resistance in fish. In the current study, hot water extract (HWE) from mushroom stalk waste (MSW) was used to formulate fish feed and hence administered to red hybrid tilapia to observe the activation of immune system. Upon 30 days of feeding, the fish were challenged with pathogen-associated molecular patterns (PAMPs) such as lipopolysaccharides (LPS) and polyinosinic:polycytidylic acid (poly (I:C)) to mimic bacterial and viral infection, respectively. HWE supplementation promoted better feed utilisation in red hybrid tilapia although it did not increase the body weight gain and specific growth rate compared to the control diet. The innate immunological parameters such as phagocytic activity and respiratory burst activity were significantly higher in HWE-supplemented group than that of the control group following PAMPs challenges. HWE-supplemented diet also resulted in higher mRNA transcription of il1b and tnfa in midgut, spleen and head kidney at 1-day post PAMPs injection. Tlr3 exhibited the highest upregulation in the HWE fed fish injected with poly (I:C). At 3-days post PAMPs injection, both ighm and tcrb expression were upregulated significantly in the spleen and head kidney. Results showed that HWE supplementation enhances the immune responses of red hybrid tilapia and induced a higher serum bactericidal activity against S. agalactiae.

Matched MeSH terms: Streptococcus agalactiae/immunology
Fulltext Vaccine Efficacy of a Newly Developed Feed-Based Whole-Cell Polyvalent Vaccine against Vibriosis, Streptococcosis and Motile Aeromonad Septicemia in Asian Seabass, Lates calcarifer

Mohamad A, Zamri-Saad M, Amal MNA, Al-Saari N, Monir MS, Chin YK, et al.

Vaccines (Basel), 2021 Apr 10;9(4).
PMID: 33920311 DOI: 10.3390/vaccines9040368

Multiple infections of several bacterial species are often observed under natural farm conditions. The infections would cause a much more significant loss compared to a single infectious agent. Vaccination is an essential strategy to prevent diseases in aquaculture, and oral vaccination has been proposed as a promising technique since it requires no handling of the fish and is easy to perform. This research attempts to develop and evaluate a potential feed-based polyvalent vaccine that can be used to treat multiple infections by Vibrios spp., Streptococcus agalactiae, and Aeromonas hydrophila, simultaneously. The oral polyvalent vaccine was prepared by mixing formalin-killed vaccine of V. harveyi, S. agalactiae, and A. hydrophila strains with commercial feed pellet, and palm oil as an adjuvant was added to improve their antigenicity. Thereafter, a vaccinated feed pellet was tested for feed quality analysis in terms of feed stability in water, proximate nutrient analysis, and palatability, safety, and growth performance using Asian seabass, Lates calcarifer as a fish host model. For immune response analysis, a total of 300 Asian seabass juveniles (15.8 ± 2.6 g) were divided into two groups in triplicate. Fish of group 1 were not vaccinated, while group 2 was vaccinated with the feed-based polyvalent vaccine. Vaccinations were carried out on days 0 and 14 with oral administration of the feed containing the bacterin at 5% body weight. Samples of serum for antibody and lysozyme study and the spleen and gut for gene expression analysis were collected at 7-day intervals for 6 weeks. Its efficacy in protecting fish was evaluated in aquarium challenge. Following vaccination by the polyvalent feed-based vaccine, IgM antibody levels showed a significant (p < 0.05) increase in serum against Vibrio harveyi, Aeromonas hydrophila, and Streptococcus agalactiae and reached the peak at week 3, 5, and 6, respectively. The high-stimulated antibody in the serum remained significantly higher than the control (p < 0.05) at the end of the 6 weeks vaccination trial. Not only that, but the serum lysozyme level was also increased significantly at week 4 (p < 0.05) as compared to the control treatment. The immune-related gene, dendritic cells, C3, Chemokine ligand 4 (CCL4), and major histocompatibility complex class I (MHC I) showed significantly higher expression (p < 0.05) after the fish were vaccinated with the oral vaccine. In the aquarium challenge, the vaccine provided a relative percentage survival of 75 ± 7.1%, 80 ± 0.0%, and 80 ± 0.0% after challenge with V. harveyi, A. hydrophila, and S. agalactiae, respectively. Combining our results demonstrate that the feed-based polyvalent vaccine could elicit significant innate and adaptive immunological responses, and this offers an opportunity for a comprehensive immunization against vibriosis, streptococcosis, and motile aeromonad septicemia in Asian seabass, Lates calcarifer. Nevertheless, this newly developed feed-based polyvalent vaccination can be a promising technique for effective and large-scale fish immunization in the aquaculture industry shortly.

Matched MeSH terms: Streptococcus agalactiae

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