Fluoroquinolones in the treatment of typhoid fever and the carrier state

Typhoid fever remains an important public health problem throughout the world with a higher morbidity and mortality rate in the developing countries. Early establishment of the diagnosis and prompt initiation of treatment with chloramphenicol, ampicillin or trimethoprim-sulfamethoxazole is not necessarily followed by complete resolution of the infection. Between 1 % and 6 % of patients with typhoid fever become chronic biliary carriers ofSalmonella typhi. These carriers are potential factors in the continued transmission of the disease. The increasing emergence worldwide of strains showing multiple resistance to the agents traditionally used in therapy has encouraged investigators to seek alternatives such as third generation cephalosporins and recently the new 4-quinolones, which have greater activity againstSalmonella typhi including multi-resistant strains. The fluoroquinolones seem to be the treatment of choice in those regions where resistant strains ofSalmonella typhi are prevalent.     

Epidemiological analysis of the influenza virus A carrier state in healthy children

Clinical and laboratory examinations in two permanently observed children's institutions were carried out in 1968--1978. Altogether, 241 children were examined virologically 759 times, of them 181 children were found to be truly healthy. In the epidemic period the latter yielded virus in 3.7%, in the interepidemic period in 1%. Unlike asymptomatic infection, transitory virus carrier state was not accompanied by antibody production, and in a number of such cases subsequently led to an overt clinical disease.     

Neutralizing antibodies for sandfly fever Naples virus in human sera on the island of Mljet

Sera from apparently healthy residents of various age from different localities of the Adriatic island of Mljet were tested by the plaque reduction neutralization test (PRNT) for antibodies to sandfly fever Naples virus (SFN). An average of 51.4% of the sera examined was found to have neutralizing antibodies. Reactors to SFN virus were found in all the age groups examined and the antibody prevalence appeared to increase with age. The presence of SFN neutralizing antibodies in all age groups indicates that the virus must have been present endemically and that it is still active on the island of Mljet.     

Foot-and-mouth disease virus carrier state in cells cultured from tissues of convalescent cattle

Summary Cultures were made from mucosal tissues of the pharynx, esophagus, rumen and tongue of cattle convalescent (7 days) from foot-and-mouth disease (FMD) infection. The persistence of FMD virus in the cell cultures was demonstrated by fluorescent antibody technique and by subcultures in primary swine kidney cells using cytopathic effect and plaque assay techniques.Virus persisted in the cell cultures and was found in the supernatant fluids, in washed and lysed cells, and in cells by fluorescent antibody reaction of the various samples for the number of weeks indicated, respectively: tongue — 3, 3, 5; rumen — 5, 5, 7; pharynx — 25, 25, 24; and esophagus — 25, 16 (intermittently), 24. Interferon was not detected in the supernatant fluids of any of the cultures.The virus-laden cultures did not show gross signs of infection, whereas mucosal cultures from similar areas of normal cattle were destroyed in about 18 hours after inoculation with stock virus. Both the infected cultures and noninfected normal cultures deteriorated after 25 to 26 weeks.The carrier virus isolated at 22 weeks from the esophageal and pharyngeal cultures showed decreased pathogenicity to different primary and cell line kidney cultures and to mice, as compared to the parent virus. The carrier viral isolates were infective for cattle. However, esophageal-pharyngeal (EP) fluids from steers inoculated with the carrier virus isolated from the esophageal culture at 22 weeks contained more virus at 7 and 14 days than the EP fluids from a steer inoculated with the carrier virus isolated from the pharyngeal cell cultures.     

Prevalence of antibodies to phleboviruses within the sand fly fever Naples virus species in humans,northern Greece

Phleboviruses are commonly detected in the Mediterranean region. In order to estimate the seroprevalence to Toscana virus (TOSV) and TOSV-like viruses in the human population in northern Greece, we tested serum samples from 595 apparently healthy individuals aged 1–87 years (median: 45 years) for the presence of TOSV IgG antibodies. A seroprevalence of 11.26% was observed, ranging from 0% to 23.5%. Seropositivity was significantly lower in children and adults <30 years of age. The high seroprevalence (<10%) observed in several prefectures of northern Greece suggests that an important proportion of infections caused by TOSV or TOSV-like viruses may be asymptomatic or mild, and therefore underestimated. Increased awareness of physicians is needed during the summer months, when sand flies are active and have the potential to transmit phleboviruses to humans.     

A carrier cell line of measles virus in Lu 106 cells

Summary A measles virus carrier cell line in Lu 106 cells is described. In most passages more than 90% of infected cells exhibited a hemadsorbing capacity. The virus products released from the carrier cells mainly were non-infectious components. After equilibrium centrifugation in CsCl gradients the occurrence of a relative increase in hemagglutinin of lower density, 1.21 to 1.20 g./cc., was frequently found.The carrier cells were completely resistant to superinfection with the homologous type of virus. Furthermore the plating efficiency of a virulent strain of poliovirus type 1 on carrier cells as compared to normal cells was markedly reduced. However, no interference was demonstrable with Sendai, vaccinia and adenovirus type 3. No Interferon was detectable in concentrated material. No induction occurred when the carrier cells were propagated in the presence of 0.05g. actinomycin per ml. A reduction in the temperature of incubation from 37° C to 33° C caused a gradually increasing occurrence of cytopathic changes eventually leading to a complete destruction of the monolayer of carrier cells. It is concluded that the carrier state presumably is dependent upon factors other than or additional to a production of Interferon.Supported by grants from the Swedish Medical Research Council (Project No.16 X-603-02) and from the foundation Therese and Johan Anderssons minne.     

Association of hepatitis C virus carrier state with the occurrence of hepatitis C virus core antibodies.

An enzyme immunoassay (EIA) was developed for the determination of antibodies against the "putative" core protein of hepatitis C virus (HCV). Antigens used were recombinant fragments (amino acids 6-77 or 6-143) of the HCV core protein, produced in Escherichia coli with truncated hepatitis B core (HBc) as fusion protein. Evaluation of 385 sera positive for HCV antibodies by first generation EIA, revealed 98 (25.4%) with HCV core antibodies. HCV-RNA, determined by the polymerase chain reaction (PCR), was exclusively found in the sera positive for HCV core antibodies (89 PCR positives). In random screening of 3,708 sera, 3 sera with HCV core antibodies were found PCR positive. Only 2 of these sera were positive in the first generation EIA. It is concluded that HCV core antibody determination is a reliable test for identifying HCV carriers among blood donors.     

Differential cytokine responses from primary human Kupffer cells following infection with wild-type or vaccine strain yellow fever virus

Wild-type yellow fever virus (YFV) infections result in a hepatotropic disease which is often fatal, while vaccination with the live-attenuated 17-D strain results in productive infection yet is well-tolerated with few adverse events. Kupffer cells (KCs) are resident liver macrophages that have a significant role in pathogen detection, clearance and immune signaling. Although KCs appear to be an important component of YF disease, their role has been under-studied. This study examined cytokine responses in KCs following infection with either wild-type or vaccine strains of YFV. Results indicate that KCs support replication of both wild-type and vaccine strains, yet wild-type YFV induced a prominent and prolonged pro-inflammatory cytokine response (IL-8, TNF-α and RANTES/CCL5) with little control by a major anti-inflammatory cytokine (IL-10). This response was significantly reduced in vaccine strain infections. These data suggest that a differentially regulated infection in KCs may play a critical role in development of disease.     

Synthesis of DNA in cells infected with African swine fever virus

Summary Incorporation of¹⁴C-thymidine by cells infected with African swine fever virus (ASFV) occurs in the nucleus. Part of this DNA is transferred to the cytoplasm and becomes resistant to DNAse. The nuclear fraction washed with Triton X 100 retained all labeled DNA and was able to synthesize viral and cellular DNA underin vitro conditions in the presence of the four deoxynucleoside triphosphates, Mg⁺², and sucrose. Under similar conditions nuclei from uninfected cells synthesized very little DNA.With 4 Figures     

Effect of prostaglandin A1 in porcine cells persistently infected with classical swine fever virus

Cyclopentenone prostaglandins are potent inhibitors of a wide variety of RNA and DNA viruses. In this report we describe that prostaglandin A1 (PGA1) potently inhibited the replication of classical swine fever virus in cultures of PK-15 cells. The highest non-toxic dose (5 microg/ml) inhibited virus yield in 99% at the initial phase of infection and in 77% in persistent infected cells. However when PGA1 was removed from persistently infected cells, the inhibition of virus replication was partially reverted.     

Feline calicivirus carrier state a study of the host/virus relationship

Summary The inter-epidemic phase of feline calicivirus was studied in a number of cats. During this period animals asymptomatically shed infective virus which was monitored at a number of sites and during different environmental conditions. Analysis of the amounts of virus shed by different cats showed that excretion occurred almost exclusively from the oropharynx, fluctuated with time, but was not influenced by periods of natural or artificial stress. Viral excretion from one individual cat was fairly constant although it appears that cats might be divided into high, medium or low level excretors. This variation in levels of excretion appears to have epidemiological importance in that high-level excretors more easily infect susceptible individuals.With 2 Figures     

Sensitivity of methods of titration of the vaccine strain of porcine fever virus

Methods of titration of the CS vaccine strain of classical swine fever virus were compared in vitro and vivo. The titration in the TL and PK-15 cell culture without cytopathic effect is based on the detection of virus antigen by labeled antibodies. The infection intensity in the cell culture virtually correlated with the antigenic and immunogenic activity of dry vaccine used for swine.     

乙型肝炎病毒全基因克隆及序列分析发现一D/C基因型重组株

目的 构建含有adr、adw、ayw3个血清型的HBV全基因组质粒，并进行测序及序列分析。方法 从HBsAg携带者的血清中扩增出S区克隆，筛选出adr、adw、ayw血清型的血清，然后扩增HBV的全基因组，对扩增产物进行克隆测序。利用DNAStar的MegAlign，Phylogenetic tree对HBV全基因序列以及分段序列进行比较和进化树分析。结果 构建了含有adw、adr、ayw 3种血清型的HBV全基因组质粒，代码分别为：H1、H2、H3，对3株完成序列测定，按照S区核苷酸顺序划分基因型分别为B、C、D，全序列分型显示H1、H2为B、C基因型，与按S区的分型一致，但H3为C基因型，与按S区的分型不同，进一步的序列分析表明H3为一株异常的基因型，按照S区和preS2区分型为D基因型，但是全基因组／C／P／X区的进化树分析，H3株均位于C基因型，提示该异常的基因型可能是由于D／C基因型间基因重组引起，对重组位点进行了分析：3181nt-10nt、799-834nt为可能的重组位点所在区。结论 H3病毒株的发现进一步证明了HBV基因型间的基因重组，但澄清该问题需要在HBV感染的高流行区进一步的积累HBV异常基因型的全序列，以及发现新的基因型资料。